2023
|
Charreau, J., Blard, P. H., Lavé, J., Dominguez, S., Li, W. S. Unsteady topography in the eastern Tianshan due to imbalance between denudation and crustal thickening (Article de journal) Dans: Tectonophysics, vol. 848, p. 229702, 2023. @article{Charreau_etal2023,
title = {Unsteady topography in the eastern Tianshan due to imbalance between denudation and crustal thickening},
author = {J. Charreau and P. H. Blard and J. Lav\'{e} and S. Dominguez and W. S. Li},
doi = {10.1016/j.tecto.2022.229702},
year = {2023},
date = {2023-01-01},
journal = {Tectonophysics},
volume = {848},
pages = {229702},
abstract = {The Tianshan mountains have complex and variable topography and documenting their growth is important for understanding both intracontinental mountain building and the evolution of the global climate. We investigate whether this topography is in equilibrium with crustal influx (thickening) and sediment outflux (denudation).Based on literature, we estimate that the eastern Tianshan has been subject to a total crustal shortening rate of textasciitilde9.4 mm/a across the Kuitun--Kuche transect, implying textasciitilde1.3 mm/a of crustal thickening and a total crustal influx of textasciitilde9 texttimes 107 m3/a. We measured in-situ cosmogenic 10Be concentrations in modern river sands of 34 catchments to constrain recent (0--6 ka) basin-averaged denudation rates within the range and on its two flanks. Denudation rates range from 0.020 textpm 0.002 to 0.53 textpm 0.07 mm/a, averaging 0.20 textpm 0.04 and 0.11 textpm 0.02 mm/a in the north and south, respectively; these rates correspond to respective total sediment outfluxes of (542 textpm 69) texttimes 104 and (164 textpm 24) texttimes 104 m3/a. To ensure that these values can be compared to Pleistocene tectonic rates, we reconstructed Pleistocene denudation rates in seven of the studied basins. For this, we determined inherited insitu cosmogenic 10Be concentrations from 11 cosmogenic depth profiles of abandoned fluvial terraces deposited in the Tianshan piedmonts. These data indicate that denudation rates have been relatively steady since the Pleistocene and thus that recent and Pleistocene sediment fluxes can be compared. These results show that crustal thickening outpaced denudation and sediment outflux by a factor of textasciitilde10. Therefore, the Tianshan topography is not in dynamic equilibrium and is growing, even if materials are being subducted into the mantle. Consequently, to sustain this disequilibrium, the range grew laterally. This lateral growth and the inheritance of structures and basins are likely responsible for the complex topography of the range.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The Tianshan mountains have complex and variable topography and documenting their growth is important for understanding both intracontinental mountain building and the evolution of the global climate. We investigate whether this topography is in equilibrium with crustal influx (thickening) and sediment outflux (denudation).Based on literature, we estimate that the eastern Tianshan has been subject to a total crustal shortening rate of textasciitilde9.4 mm/a across the Kuitun--Kuche transect, implying textasciitilde1.3 mm/a of crustal thickening and a total crustal influx of textasciitilde9 texttimes 107 m3/a. We measured in-situ cosmogenic 10Be concentrations in modern river sands of 34 catchments to constrain recent (0--6 ka) basin-averaged denudation rates within the range and on its two flanks. Denudation rates range from 0.020 textpm 0.002 to 0.53 textpm 0.07 mm/a, averaging 0.20 textpm 0.04 and 0.11 textpm 0.02 mm/a in the north and south, respectively; these rates correspond to respective total sediment outfluxes of (542 textpm 69) texttimes 104 and (164 textpm 24) texttimes 104 m3/a. To ensure that these values can be compared to Pleistocene tectonic rates, we reconstructed Pleistocene denudation rates in seven of the studied basins. For this, we determined inherited insitu cosmogenic 10Be concentrations from 11 cosmogenic depth profiles of abandoned fluvial terraces deposited in the Tianshan piedmonts. These data indicate that denudation rates have been relatively steady since the Pleistocene and thus that recent and Pleistocene sediment fluxes can be compared. These results show that crustal thickening outpaced denudation and sediment outflux by a factor of textasciitilde10. Therefore, the Tianshan topography is not in dynamic equilibrium and is growing, even if materials are being subducted into the mantle. Consequently, to sustain this disequilibrium, the range grew laterally. This lateral growth and the inheritance of structures and basins are likely responsible for the complex topography of the range. |
2022
|
Lacroix, S., Gavillon, T., Bouchant, C., Lavé, J., Mugnier, J. L., Dhungel, S., Vernier, F. SAR and optical images correlation illuminates postâseismic landslide motion after the Mw 7.8 Gorkha earthquake (Nepal) (Article de journal) Dans: Scientific Reports, vol. 12, no. 6266, 2022. @article{Lacroix_etal2022,
title = {SAR and optical images correlation illuminates post\^{a}seismic landslide motion after the Mw 7.8 Gorkha earthquake (Nepal)},
author = {S. Lacroix and T. Gavillon and C. Bouchant and J. Lav\'{e} and J. L. Mugnier and S. Dhungel and F. Vernier},
doi = {10.1038/s41598-022-10016-2},
year = {2022},
date = {2022-01-01},
journal = {Scientific Reports},
volume = {12},
number = {6266},
abstract = {In the days to weeks following an earthquake, landslides can display specific post-seismic motions,including delayed initiations and post-seismic relaxations. These motions have an uncertain origin, sometimes attributed to specificities of the landslide basal interface or to fluid transports in the landslide basal shear zone. Here we address this question, by documenting the co- and post-seismic motions of slow-moving landslides accelerated by the Gorkha earthquake (Mw 7.8, 25/04/2015,Nepal). We detect 11 slow-moving landslides over an area of 750 km2 in the near field of the earthquake, and monitor their motions thanks to a time-series of Pl\'{e}iades optical satellite images and SAR Sentinel-1 images. The post-seismic landslide motions are much larger than the co-seismic ones, reaching up to 34 textpm 0.6 m accommodated over 2 months. A delayed initiation of several days (\> 4days) is also measured for at least two of the landslides. We analyze our findings in regards with all the previous observations on slow-moving landslides accelerated by earthquakes, and propose that the post-seismic motions are caused by diffusion of groundwater from co-seismic material contraction up to the landslide basal shear zone or from internal landslide reconfiguration. Our observations stronglysuggest the main control of the hydrology in the landslide processes under seismic forcings.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the days to weeks following an earthquake, landslides can display specific post-seismic motions,including delayed initiations and post-seismic relaxations. These motions have an uncertain origin, sometimes attributed to specificities of the landslide basal interface or to fluid transports in the landslide basal shear zone. Here we address this question, by documenting the co- and post-seismic motions of slow-moving landslides accelerated by the Gorkha earthquake (Mw 7.8, 25/04/2015,Nepal). We detect 11 slow-moving landslides over an area of 750 km2 in the near field of the earthquake, and monitor their motions thanks to a time-series of Pléiades optical satellite images and SAR Sentinel-1 images. The post-seismic landslide motions are much larger than the co-seismic ones, reaching up to 34 textpm 0.6 m accommodated over 2 months. A delayed initiation of several days (> 4days) is also measured for at least two of the landslides. We analyze our findings in regards with all the previous observations on slow-moving landslides accelerated by earthquakes, and propose that the post-seismic motions are caused by diffusion of groundwater from co-seismic material contraction up to the landslide basal shear zone or from internal landslide reconfiguration. Our observations stronglysuggest the main control of the hydrology in the landslide processes under seismic forcings. |
2021
|
Märki, L., Lupker, M., France-Lanord, C., Lavé, J., Gallen, S., Gajurel, A. P., Haguipour, N., Leuenberger-West, F., Eglinton, T. An unshakable carbon budget for the Himalaya (Article de journal) Dans: Nature Geoscience, 2021. @article{Mrki_etal2021,
title = {An unshakable carbon budget for the Himalaya},
author = {L. M\"{a}rki and M. Lupker and C. France-Lanord and J. Lav\'{e} and S. Gallen and A. P. Gajurel and N. Haguipour and F. Leuenberger-West and T. Eglinton},
doi = {10.1038/s41561-021-00815-z},
year = {2021},
date = {2021-01-01},
journal = {Nature Geoscience},
abstract = {The erosion and weathering of mountain ranges exert a key control on the long-term (105--106 yr) cycling of carbon between Earthtextquoterights surface and crust. The net carbon budget of a mountain range reflects the co-existence of multiple carbon sources andsinks, with corresponding fluxes remaining difficult to quantify. Uncertain responses of these carbon fluxes due to the stochastic nature of erosional processes further complicate the extrapolation of short-term observations to longer, climatically relevant timescales. Here, we quantify the evolution of the organic and inorganic carbon fluxes in response to the 2015 Gorkha earthquake (Mw 7.8) in the central Himalaya. We find that the Himalayan erosion acts as a net carbon sink due mainly to efficient biospheric organic carbon export. Our high-resolution time series encompassing four monsoon seasons before and afterthe Gorkha earthquake reveal that coseismic landslides did not significantly perturb large-scale Himalayan sediment and carbon fluxes. This muted response of the central Himalaya to a geologically frequent perturbation such as the Gorkha earthquake further suggests that our estimates are representative of at least interglacial timescales.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The erosion and weathering of mountain ranges exert a key control on the long-term (105--106 yr) cycling of carbon between Earthtextquoterights surface and crust. The net carbon budget of a mountain range reflects the co-existence of multiple carbon sources andsinks, with corresponding fluxes remaining difficult to quantify. Uncertain responses of these carbon fluxes due to the stochastic nature of erosional processes further complicate the extrapolation of short-term observations to longer, climatically relevant timescales. Here, we quantify the evolution of the organic and inorganic carbon fluxes in response to the 2015 Gorkha earthquake (Mw 7.8) in the central Himalaya. We find that the Himalayan erosion acts as a net carbon sink due mainly to efficient biospheric organic carbon export. Our high-resolution time series encompassing four monsoon seasons before and afterthe Gorkha earthquake reveal that coseismic landslides did not significantly perturb large-scale Himalayan sediment and carbon fluxes. This muted response of the central Himalaya to a geologically frequent perturbation such as the Gorkha earthquake further suggests that our estimates are representative of at least interglacial timescales. |
2020
|
Charreau, J., Lavé, J., France-Lanord, C., Puchol, N., Blard, P. H., Pik, R., Gajurel, A. P., Team., ASTER A 6 Ma record of palaeodenudation in the central Himalayas from in situ cosmogenic 10 Be in the Surai section (Article de journal) Dans: Basin Research, p. 1–22, 2020. @article{Charreau_etal2020,
title = {A 6 Ma record of palaeodenudation in the central Himalayas from in situ cosmogenic 10 Be in the Surai section},
author = {J. Charreau and J. Lav\'{e} and C. France-Lanord and N. Puchol and P. H. Blard and R. Pik and A. P. Gajurel and ASTER Team.},
doi = {10.1111/bre.12511},
year = {2020},
date = {2020-01-01},
journal = {Basin Research},
pages = {1--22},
abstract = {To better constrain late Neogene denudation of the Himalayas, we analysed in situ 10Be concentrations in 17 Neogene sediment samples of the Surai section (central Nepal) and two modern sediment samples of the Rapti River. We first refined the depositional ages of the Surai section from 36 new paleomagnetic analyses, five 26Al/10Be burial ages, and, based on the Dynamic Time Warping algorithm, 104 automatically calculated likely magnetostratigraphic correlations. We also traced changing sediment sources using major element and Sr-Nd isotopic data, finding at 4--3Ma a switch from a large, trans-Himalayan river to a river draining only the Lesser Himalaya and Siwalik piedmont, increasing the contribution of recycled sediments at that time. 10Be concentrations in Neogene sediments range from (1.00 textpm0.36) to (5.22textpm0.98)texttimes103 at g--1 and decrease with stratigraphic age. Based on a flood plain transport model, our refined age model, and assuming a drainage change at 4--3Ma, we reconstructed 10Be concentrations at the time of deposition. Assuming cosmogenic production rates similar to those of the modern basins, we calculated palaeodenudation rates of 0.9textpm0.5 to 3.9textpm2.7mm a --1 from ca. 6 to 3Ma in the palaeo-Karnali basin and 0.6textpm0.2 to 1.6textpm0.8mm a --1 since ca. 3Ma in the palaeo-Rapti basin. Given the uncertainties and similar modern values of 2mm a--1, the palaeo-Karnali denudation rates may have been steady at 1.7textpm0.3mm a--1 for the last ca. 6Ma. A transient acceleration of the denudation in the palaeo-Rapti basin of 1.5mm a--1 since ca. 1.5Ma was likely due to the reworking of older, 10Be-depleted Siwalik sediments in the foreland. If true, this steadiness of the denudation rates may suggest that Quaternary glaciations did not largely affect Himalayan denudation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
To better constrain late Neogene denudation of the Himalayas, we analysed in situ 10Be concentrations in 17 Neogene sediment samples of the Surai section (central Nepal) and two modern sediment samples of the Rapti River. We first refined the depositional ages of the Surai section from 36 new paleomagnetic analyses, five 26Al/10Be burial ages, and, based on the Dynamic Time Warping algorithm, 104 automatically calculated likely magnetostratigraphic correlations. We also traced changing sediment sources using major element and Sr-Nd isotopic data, finding at 4--3Ma a switch from a large, trans-Himalayan river to a river draining only the Lesser Himalaya and Siwalik piedmont, increasing the contribution of recycled sediments at that time. 10Be concentrations in Neogene sediments range from (1.00 textpm0.36) to (5.22textpm0.98)texttimes103 at g--1 and decrease with stratigraphic age. Based on a flood plain transport model, our refined age model, and assuming a drainage change at 4--3Ma, we reconstructed 10Be concentrations at the time of deposition. Assuming cosmogenic production rates similar to those of the modern basins, we calculated palaeodenudation rates of 0.9textpm0.5 to 3.9textpm2.7mm a --1 from ca. 6 to 3Ma in the palaeo-Karnali basin and 0.6textpm0.2 to 1.6textpm0.8mm a --1 since ca. 3Ma in the palaeo-Rapti basin. Given the uncertainties and similar modern values of 2mm a--1, the palaeo-Karnali denudation rates may have been steady at 1.7textpm0.3mm a--1 for the last ca. 6Ma. A transient acceleration of the denudation in the palaeo-Rapti basin of 1.5mm a--1 since ca. 1.5Ma was likely due to the reworking of older, 10Be-depleted Siwalik sediments in the foreland. If true, this steadiness of the denudation rates may suggest that Quaternary glaciations did not largely affect Himalayan denudation. |
Charreau, J., Sartégou, A., Saint-Carlier, D., Lavé, J., Blard, P. H., Dominguez, S., Wang, S. Li, Rao, G., Team., ASTER Late Miocene to Quaternary slip history across the Qiulitag anticline in the southern Tianshan piedmont (Article de journal) Dans: Terra Nova, vol. 32, p. 89–96, 2020. @article{Charreau_etal2020_2,
title = {Late Miocene to Quaternary slip history across the Qiulitag anticline in the southern Tianshan piedmont},
author = {J. Charreau and A. Sart\'{e}gou and D. Saint-Carlier and J. Lav\'{e} and P. H. Blard and S. Dominguez and S. Li Wang and G. Rao and ASTER Team.},
doi = {10.1111/ter.12439},
year = {2020},
date = {2020-01-01},
journal = {Terra Nova},
volume = {32},
pages = {89--96},
abstract = {In this study, we reconstruct the Miocene to Quaternary shortening history acrossthe Qiulitag anticline, a complex fault-bend fold located in southern Tianshan. Westudied the Yaha and Kuche sections, where we combined surface structural measurements and seismic imaging to model the stratigraphic horizons. The history of folding was reconstructed based on magnetostratigraphic analyses and eight cosmogenic burial ages in Kuche. Pleistocene deformation rates were also quantifiedin Yaha based on a deformed fluvial terrace that we dated to textasciitilde67 ka using a cosmogenic depth profile. Our results suggest that the fold grew at a mean slip rate of 0.9--1.3 mm/a in both sections but accelerated to textasciitilde2.5 mm/a during the Pleistocene in Kuche. These results support a migration of the deformation towards the basin during the Pleistocene and suggest that most of the present deformation in the Tianshan is accommodated across the external structures of the range.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this study, we reconstruct the Miocene to Quaternary shortening history acrossthe Qiulitag anticline, a complex fault-bend fold located in southern Tianshan. Westudied the Yaha and Kuche sections, where we combined surface structural measurements and seismic imaging to model the stratigraphic horizons. The history of folding was reconstructed based on magnetostratigraphic analyses and eight cosmogenic burial ages in Kuche. Pleistocene deformation rates were also quantifiedin Yaha based on a deformed fluvial terrace that we dated to textasciitilde67 ka using a cosmogenic depth profile. Our results suggest that the fold grew at a mean slip rate of 0.9--1.3 mm/a in both sections but accelerated to textasciitilde2.5 mm/a during the Pleistocene in Kuche. These results support a migration of the deformation towards the basin during the Pleistocene and suggest that most of the present deformation in the Tianshan is accommodated across the external structures of the range. |
Lénard, S., Cruz, J., France-Lanord, C., Lavé, J., Reilly, B. T. Data report : calcareous nannofossils and lithologic constraints on the age model of IODP Site U1450, Expedition 354, Bengal Fan (Article de journal) Dans: Proceedings of the International Ocean Discovery Program, vol. 354, p. 1–5, 2020. @article{Lnard_etal2020,
title = {Data report : calcareous nannofossils and lithologic constraints on the age model of IODP Site U1450, Expedition 354, Bengal Fan},
author = {S. L\'{e}nard and J. Cruz and C. France-Lanord and J. Lav\'{e} and B. T. Reilly},
doi = {10.14379/iodp.proc.354.203.2020},
year = {2020},
date = {2020-01-01},
journal = {Proceedings of the International Ocean Discovery Program},
volume = {354},
pages = {1--5},
abstract = {International Ocean Discovery Program (IODP) Expedition 354 Site U1450 was drilled at the center of a transect of 7 sites across the Bengal Fan at 8textdegreeN where long-term accumulation rates are highest. Site U1450 primarily consists of sandy and silty-sandy turbidites deposited at a rate higher than 20 cm/ky. During periods when the depocenter shifted away from Site U1450, calcareous clay hemipelagic sediment was deposited at lower accumulation rates around 1--2 cm/ky. Dating of the lower Pleistocene and Pliocene sequences is hindered by the scarcity of microfossils in turbidites and the restriction of paleomagnetic data to the upper 190 m. This report presents the identification of new calcareous nannofossils collected from hemipelagic and turbiditic intervals between 218 and 687 m core depth below seafloor, Method A (CSF-A). These data are consolidated in a statistical age model that is constrained with ranges of plausible accumulation rates for the distinct lithologies. The age probability model ranges from 1.2 to 7.3 Ma for depths from 175.8 to 812.0 m CSF-A. Depending on constraints, 2$sigma$ uncertainties are around textpm0.2 and 0.4 Ma.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
International Ocean Discovery Program (IODP) Expedition 354 Site U1450 was drilled at the center of a transect of 7 sites across the Bengal Fan at 8textdegreeN where long-term accumulation rates are highest. Site U1450 primarily consists of sandy and silty-sandy turbidites deposited at a rate higher than 20 cm/ky. During periods when the depocenter shifted away from Site U1450, calcareous clay hemipelagic sediment was deposited at lower accumulation rates around 1--2 cm/ky. Dating of the lower Pleistocene and Pliocene sequences is hindered by the scarcity of microfossils in turbidites and the restriction of paleomagnetic data to the upper 190 m. This report presents the identification of new calcareous nannofossils collected from hemipelagic and turbiditic intervals between 218 and 687 m core depth below seafloor, Method A (CSF-A). These data are consolidated in a statistical age model that is constrained with ranges of plausible accumulation rates for the distinct lithologies. The age probability model ranges from 1.2 to 7.3 Ma for depths from 175.8 to 812.0 m CSF-A. Depending on constraints, 2$sigma$ uncertainties are around textpm0.2 and 0.4 Ma. |
Lénard, S., Lavé, J., France-Lanord, C., Auma^itre, G., Bourl`es, D., Keddadouche, K. Steady erosion rates in the Himalayas through late Cenozoic climatic changes (Article de journal) Dans: Nature Geoscience, 2020. @article{Lnard_etal2020_2,
title = {Steady erosion rates in the Himalayas through late Cenozoic climatic changes},
author = {S. L\'{e}nard and J. Lav\'{e} and C. France-Lanord and G. Auma^itre and D. Bourl`es and K. Keddadouche},
doi = {10.1038/s41561-020-0585-2},
year = {2020},
date = {2020-01-01},
journal = {Nature Geoscience},
abstract = {Sediment accumulation rates and thermal trackers suggest a substantial and global increase in erosion rates over the past few million years. That increase is commonly associated with the impact of the Northern Hemisphere glaciation, but methodological biases have led researchers to debate this hypothesis. Here, we test whether Himalayan erosion rates increased by measuring beryllium-10 (10Be) in the sediment of the Bengal Bay seabed. Sediment originated from rocks that produced 10Be under the impact of cosmic rays during erosion near surface. Thus, the 10Be concentrations indicate erosion rates. The 10Be concentration of the Bengal Bay sediment depends on the contributions of the Ganga and Brahmaputra rivers. Their sediments have distinct 10Be concentrations because of distinct elevations and erosion in their drainage basins. Variable contributions could thus complicate erosion-rate calculation. We traced these contributions by a provenance study using the strontium (Sr) and neodymium (Nd) isotopic sediment compositions. Within uncertainties of textpm30%, our reconstructed past erosion rates show no long-term increase for the past six million years. This stability suggests that climatic changes during the late Cenozoic have an undetectable impact on the erosion patterns in the Himalayas, at least on the ten thousand to million year timescales accounted for by our dataset.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sediment accumulation rates and thermal trackers suggest a substantial and global increase in erosion rates over the past few million years. That increase is commonly associated with the impact of the Northern Hemisphere glaciation, but methodological biases have led researchers to debate this hypothesis. Here, we test whether Himalayan erosion rates increased by measuring beryllium-10 (10Be) in the sediment of the Bengal Bay seabed. Sediment originated from rocks that produced 10Be under the impact of cosmic rays during erosion near surface. Thus, the 10Be concentrations indicate erosion rates. The 10Be concentration of the Bengal Bay sediment depends on the contributions of the Ganga and Brahmaputra rivers. Their sediments have distinct 10Be concentrations because of distinct elevations and erosion in their drainage basins. Variable contributions could thus complicate erosion-rate calculation. We traced these contributions by a provenance study using the strontium (Sr) and neodymium (Nd) isotopic sediment compositions. Within uncertainties of textpm30%, our reconstructed past erosion rates show no long-term increase for the past six million years. This stability suggests that climatic changes during the late Cenozoic have an undetectable impact on the erosion patterns in the Himalayas, at least on the ten thousand to million year timescales accounted for by our dataset. |
Martin, L. C. P., Blard, P. H., Lavé, J., Jomelli, V., Charreau, J., Condom, T., Lupker, M. Antarctic-like temperature variations in the Tropical Andes recorded by glaciers and lakes during the last deglaciation (Article de journal) Dans: Quaternary Science Reviews, vol. 247, p. 106542, 2020. @article{Martin_etal2020,
title = {Antarctic-like temperature variations in the Tropical Andes recorded by glaciers and lakes during the last deglaciation},
author = {L. C. P. Martin and P. H. Blard and J. Lav\'{e} and V. Jomelli and J. Charreau and T. Condom and M. Lupker},
doi = {10.1016/j.quascirev.2020.106542},
year = {2020},
date = {2020-01-01},
journal = {Quaternary Science Reviews},
volume = {247},
pages = {106542},
abstract = {The respective impacts of Northern and Southern Hemispheric climatic changes on the Tropics during the last deglaciation remain poorly understood. In the High Tropical Andes, the Antarctic Cold Reversal (ACR, 14.3--12.9 ka BP) is better represented among morainic records than the Younger Dryas (12.9--11.7 ka BP). However, in the Altiplano basin (Bolivia), two cold periods of the Northern Hemisphere (Heinrich Stadial 1a, 16.5--14.5 ka BP, and the Younger Dryas) are synchronous with (i) major advances or standstills of paleoglaciers and (ii) the highstands of giant paleolakes Tauca and Coipasa.Here, we present new cosmic ray exposure (CRE) ages from glacial landforms of the Bolivian Andes that formed during the last deglaciation (Termination 1). We reconstruct the equilibrium line altitudes (ELA) associated with each moraine and use them in an inverse algorithm combining paleoglaciers and paleolake budgets to derive temperature and precipitation during the last deglaciation.Our temperature reconstruction ($Delta$T relative to present day) yields a consistent regional trend of progressive warming from $Delta$T = −5 to −2.5 textdegreeC during 17--14.5 ka BP, followed by a return to colder conditions around −4 textdegreeC during the ACR (14.5--12.9 ka BP). The Coipasa highstand (12.9--11.8 ka BP) is coeval with another warming trend followed by $Delta$T stabilization at the onset of the Holocene (ca. 10 ka BP), around −3 textdegreeC. Our results suggest that, during the last deglaciation (20--10 ka BP) atmospheric temperatures in the Tropical Andes mimicked Antarctic variability, whereas precipitation over the Altiplano was driven by changes in the Northern Hemisphere.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The respective impacts of Northern and Southern Hemispheric climatic changes on the Tropics during the last deglaciation remain poorly understood. In the High Tropical Andes, the Antarctic Cold Reversal (ACR, 14.3--12.9 ka BP) is better represented among morainic records than the Younger Dryas (12.9--11.7 ka BP). However, in the Altiplano basin (Bolivia), two cold periods of the Northern Hemisphere (Heinrich Stadial 1a, 16.5--14.5 ka BP, and the Younger Dryas) are synchronous with (i) major advances or standstills of paleoglaciers and (ii) the highstands of giant paleolakes Tauca and Coipasa.Here, we present new cosmic ray exposure (CRE) ages from glacial landforms of the Bolivian Andes that formed during the last deglaciation (Termination 1). We reconstruct the equilibrium line altitudes (ELA) associated with each moraine and use them in an inverse algorithm combining paleoglaciers and paleolake budgets to derive temperature and precipitation during the last deglaciation.Our temperature reconstruction ($Delta$T relative to present day) yields a consistent regional trend of progressive warming from $Delta$T = −5 to −2.5 textdegreeC during 17--14.5 ka BP, followed by a return to colder conditions around −4 textdegreeC during the ACR (14.5--12.9 ka BP). The Coipasa highstand (12.9--11.8 ka BP) is coeval with another warming trend followed by $Delta$T stabilization at the onset of the Holocene (ca. 10 ka BP), around −3 textdegreeC. Our results suggest that, during the last deglaciation (20--10 ka BP) atmospheric temperatures in the Tropical Andes mimicked Antarctic variability, whereas precipitation over the Altiplano was driven by changes in the Northern Hemisphere. |
Märki, L., Lupker, M., Gajurel, A. P., Gies, H., Haghipour, N., Gallen, S., France-Lanord, C., Lavé, J., Eglinton, T. Molecular tracing of riverine soil organic matter from the Central Himalaya (Article de journal) Dans: Geophysical Research Letters, vol. 47, no. 16, p. e2020GL087403, 2020. @article{Mrki_etal2020,
title = {Molecular tracing of riverine soil organic matter from the Central Himalaya},
author = {L. M\"{a}rki and M. Lupker and A. P. Gajurel and H. Gies and N. Haghipour and S. Gallen and C. France-Lanord and J. Lav\'{e} and T. Eglinton},
doi = {10.1029/2020GL087403},
year = {2020},
date = {2020-01-01},
journal = {Geophysical Research Letters},
volume = {47},
number = {16},
pages = {e2020GL087403},
abstract = {The isomer distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in soils has been shown to correlate to the local mean annual temperature. Here, we explore the use of brGDGT distributions as proxy for the elevation at which soil organic carbon is preferentially mobilized in the Central Himalaya. Soil brGDGT distributions collected along an altitudinal profile, spanning elevations from 200 to 4,450 m asl, are linearly correlated to elevation. We use this calibration to trace the provenance of soil organic matter in suspended sediments of rivers draining the Himalaya. BrGDGT distributions of fluvial sediments reflect the mean elevation of the soil cover in most catchments. Inverse modeling of the brGDGT data set suggests similar relative contribution to soil organic carbon mobilization from different land covers within a factor 2. We conclude that riverine soil organic carbon export in the Himalaya mostly occurs pervasively and is at the catchment scale insensitive to anthropogenic perturbations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The isomer distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in soils has been shown to correlate to the local mean annual temperature. Here, we explore the use of brGDGT distributions as proxy for the elevation at which soil organic carbon is preferentially mobilized in the Central Himalaya. Soil brGDGT distributions collected along an altitudinal profile, spanning elevations from 200 to 4,450 m asl, are linearly correlated to elevation. We use this calibration to trace the provenance of soil organic matter in suspended sediments of rivers draining the Himalaya. BrGDGT distributions of fluvial sediments reflect the mean elevation of the soil cover in most catchments. Inverse modeling of the brGDGT data set suggests similar relative contribution to soil organic carbon mobilization from different land covers within a factor 2. We conclude that riverine soil organic carbon export in the Himalaya mostly occurs pervasively and is at the catchment scale insensitive to anthropogenic perturbations. |
2018
|
Cassel, M., Piégay, H., Lavé, J., Vaudor, L., Hadmoko, D. S., Wibiwo, S. B., Lavigne, F. Evaluating a 2D image-based computerized approach for measuring riverine pebble roundness (Article de journal) Dans: Geomorphology, vol. 311, p. 143–157, 2018. @article{Cassel_etal2018,
title = {Evaluating a 2D image-based computerized approach for measuring riverine pebble roundness},
author = {M. Cassel and H. Pi\'{e}gay and J. Lav\'{e} and L. Vaudor and D. S. Hadmoko and S. B. Wibiwo and F. Lavigne},
doi = {10.1016/j.geomorph.2018.03.020},
year = {2018},
date = {2018-01-01},
journal = {Geomorphology},
volume = {311},
pages = {143--157},
abstract = {The geometrical characteristics of pebbles are important features to study transport pathways, sedimentary history, depositional environments, abrasion processes or to target sediment sources. Both the shape and roundness of pebbles can be described by a still growing number of metrics in 2D and 3D or by visual charts. Despite new developments, existing tools remain proprietary and no pebble roundness toolbox has been available widely within the scientific community. The toolbox developed by Roussillon et al. (2009) automatically computes the size, shape and roundness indexes of pebbles from their 2D maximal projection plans. Using a digital camera, this toolbox operates using 2D pictures taken of pebbles placed on a one square meter red board, allowing data collection to be quickly and efficiently acquired at a large scale. Now that the toolbox is freely available for download,1 an evaluation is needed to help end users sample, process and interpret the data. We first assess the influence of pebble position and of the resolution and enhancement of pictures and errors associated with the sampling size. Second, we run experimental flume tests of roundness trends that confirm the great potential of the toolbox for river geomorphic diagnoses as well as for targeting sediment sources. We also validate the correlation between roundness metric trends and particle abrasion.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The geometrical characteristics of pebbles are important features to study transport pathways, sedimentary history, depositional environments, abrasion processes or to target sediment sources. Both the shape and roundness of pebbles can be described by a still growing number of metrics in 2D and 3D or by visual charts. Despite new developments, existing tools remain proprietary and no pebble roundness toolbox has been available widely within the scientific community. The toolbox developed by Roussillon et al. (2009) automatically computes the size, shape and roundness indexes of pebbles from their 2D maximal projection plans. Using a digital camera, this toolbox operates using 2D pictures taken of pebbles placed on a one square meter red board, allowing data collection to be quickly and efficiently acquired at a large scale. Now that the toolbox is freely available for download,1 an evaluation is needed to help end users sample, process and interpret the data. We first assess the influence of pebble position and of the resolution and enhancement of pictures and errors associated with the sampling size. Second, we run experimental flume tests of roundness trends that confirm the great potential of the toolbox for river geomorphic diagnoses as well as for targeting sediment sources. We also validate the correlation between roundness metric trends and particle abrasion. |
Charreau, J., Saint-Carlier, D., Lavé, J., Dominguez, S., Blard, P. H., Avouac, J. P., Brown, N. D., Malatesta, L. C., Shengli, W., Rhodes, E. J. Late Pleistocene acceleration of deformation across the northern Tianshan piedmont (China) evidenced from the morpho-tectonic evolution of the Dushanzi anticline (Article de journal) Dans: Tectonophysics, vol. 730, p. 132–140, 2018. @article{Charreau_etal2018,
title = {Late Pleistocene acceleration of deformation across the northern Tianshan piedmont (China) evidenced from the morpho-tectonic evolution of the Dushanzi anticline},
author = {J. Charreau and D. Saint-Carlier and J. Lav\'{e} and S. Dominguez and P. H. Blard and J. P. Avouac and N. D. Brown and L. C. Malatesta and W. Shengli and E. J. Rhodes},
doi = {10.1016/j.tecto.2018.02.016},
year = {2018},
date = {2018-01-01},
journal = {Tectonophysics},
volume = {730},
pages = {132--140},
abstract = {We document the temporal evolution of deformation in the northern Tianshan piedmont where the deformation is partitioned across several thrusts and folds. We focus on the Dushanzi anticline, where abandoned terraces and growth strata allow us to constrain the history of folding since the Miocene. Based on subsurface seismic imaging, structural measurements and morphological analysis, we show that this anticline is associated with two decollement levels. We use kink band migration in growth strata dated by paleomagnetism to constrain the shortening from the Mio-Pliocene to the Holocene. Our results show that the Dushanzi anticline has been active since at least 8 Ma and that the fold grew at a steady shortening rate of 0.6 textpm 0.1 mm/yr from 8 to textasciitilde1.5 Ma with possible variations from 2.5 to 1.5 Ma. Then it accelerated rapidly to a rate of 4.3 textpm 1.0 mm/yr over at least the last 100 ka. These results, together with similar temporal shortening evolutions across other structures, suggest that the deformation rate across the eastern Tianshan piedmont increased relatively recently. This may reflect either a redistribution of the deformation from the internal structures toward the borders or a general acceleration of the deformation across the entire range.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We document the temporal evolution of deformation in the northern Tianshan piedmont where the deformation is partitioned across several thrusts and folds. We focus on the Dushanzi anticline, where abandoned terraces and growth strata allow us to constrain the history of folding since the Miocene. Based on subsurface seismic imaging, structural measurements and morphological analysis, we show that this anticline is associated with two decollement levels. We use kink band migration in growth strata dated by paleomagnetism to constrain the shortening from the Mio-Pliocene to the Holocene. Our results show that the Dushanzi anticline has been active since at least 8 Ma and that the fold grew at a steady shortening rate of 0.6 textpm 0.1 mm/yr from 8 to textasciitilde1.5 Ma with possible variations from 2.5 to 1.5 Ma. Then it accelerated rapidly to a rate of 4.3 textpm 1.0 mm/yr over at least the last 100 ka. These results, together with similar temporal shortening evolutions across other structures, suggest that the deformation rate across the eastern Tianshan piedmont increased relatively recently. This may reflect either a redistribution of the deformation from the internal structures toward the borders or a general acceleration of the deformation across the entire range. |
Martins, L., Blard, P. H., Lavé, J., Condom, T., Prémaillon, M., Jomelli, V., Brunstein, D., Lupker, M., Charreau, J., Mariotti, V., Tibari, B., Team., ASTER, Davy, E. Lake Tauca highstand (Heinrich Stadial 1a) driven by a southward shift of the Bolivian High (Article de journal) Dans: Science Advances, vol. 4, 2018. @article{Martins_etal2018,
title = {Lake Tauca highstand (Heinrich Stadial 1a) driven by a southward shift of the Bolivian High},
author = {L. Martins and P. H. Blard and J. Lav\'{e} and T. Condom and M. Pr\'{e}maillon and V. Jomelli and D. Brunstein and M. Lupker and J. Charreau and V. Mariotti and B. Tibari and ASTER Team. and E. Davy},
year = {2018},
date = {2018-01-01},
journal = {Science Advances},
volume = {4},
abstract = {Heinrich events are characterized by worldwide climate modifications. Over the Altiplano endorheic basin (high tropical Andes), the second half of Heinrich Stadial 1 (HS1a) was coeval with the highstand of the giant paleolake Tauca.However, the atmospheric mechanisms underlying this wet event are still unknown at the regional to global scale. We use cosmic-ray exposure ages of glacial landforms to reconstruct the spatial variability in the equilibrium line altitudeof the HS1a Altiplano glaciers. By combining glacier and lake modeling, we reconstruct a precipitation map for the HS1a period. Our results show that paleoprecipitation mainly increased along the Eastern Cordillera, whereas thesouthwestern region of the basin remained relatively dry. This pattern indicates a southward expansion of the easterlies, which is interpreted as being a consequence of a southward shift of the Bolivian High. The results provide a new understanding of atmospheric teleconnections during HS1 and of rainfall redistribution in a changing climate.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Heinrich events are characterized by worldwide climate modifications. Over the Altiplano endorheic basin (high tropical Andes), the second half of Heinrich Stadial 1 (HS1a) was coeval with the highstand of the giant paleolake Tauca.However, the atmospheric mechanisms underlying this wet event are still unknown at the regional to global scale. We use cosmic-ray exposure ages of glacial landforms to reconstruct the spatial variability in the equilibrium line altitudeof the HS1a Altiplano glaciers. By combining glacier and lake modeling, we reconstruct a precipitation map for the HS1a period. Our results show that paleoprecipitation mainly increased along the Eastern Cordillera, whereas thesouthwestern region of the basin remained relatively dry. This pattern indicates a southward expansion of the easterlies, which is interpreted as being a consequence of a southward shift of the Bolivian High. The results provide a new understanding of atmospheric teleconnections during HS1 and of rainfall redistribution in a changing climate. |
Morin, G. P., Lavé, J., France-Lanord, C., Rigaudier, T., Gajurel, A. P., Sinha, R. Annual sediment transport dynamics in the Narayani basin, Central Nepal : Assessing the impacts of erosion processes in the annual sediment budget (Article de journal) Dans: Journal of Geophysical Research ?Ĭ Earth Surface, vol. 123, 2018. @article{Morin_etal2018,
title = {Annual sediment transport dynamics in the Narayani basin, Central Nepal : Assessing the impacts of erosion processes in the annual sediment budget},
author = {G. P. Morin and J. Lav\'{e} and C. France-Lanord and T. Rigaudier and A. P. Gajurel and R. Sinha},
doi = {10.1029/2017JF004460},
year = {2018},
date = {2018-01-01},
journal = {Journal of Geophysical Research ?\u{I} Earth Surface},
volume = {123},
abstract = {Identifying the roles of erosional processes in the denudation of mountain ranges requires a better understanding of erosional sensitivity to climatic, topographic, or lithologic controls. We analyzed erosion in the Narayani River basin (draining central Nepal and presenting contrasted lithologic and geochemical signatures in its outcropping rocks and a wide variety of erosional processes and climaticconditions) to assess the relative contributions of erosion processes to the annual sediment export. By combining acoustic Doppler current profiler measurements with depth profiles and daily surface samplings of the suspended load, we propose a simplified model to precisely calculate sediment fluxes at the basin outlet. We estimate an equivalent erosion rate of 1:8+0:35-0:2 mm/year for the year 2010, similar to the average value of 1:6+0:35-0:2 mm/year estimated from 15 years of records and long-term (textasciitildeky) denudation rates of 1.7 mm/year derived from cosmogenic nuclides. The stability of erosion is attributed to efficient bufferingbehavior and spatial integration in the drainage system. Strong relations between rainfall events and the sediment export suggest that the system is mainly supply limited. Combining physical calculation of sediment fluxes with grain size analyses and geochemical tracers (hydroxyl isotopic compositions, carbonate contents, and total organic carbon content), we estimate that glacial and soil erosion do not contribute more than 10% and a few percentage, respectively, to the total budget and are only detectable during premonsoon and early monsoon periods. During the monsoon, erosion by landslides and mass wasting events overwhelms the sediment budget, confirming the dominant role of these erosional processes in activemountain chains.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Identifying the roles of erosional processes in the denudation of mountain ranges requires a better understanding of erosional sensitivity to climatic, topographic, or lithologic controls. We analyzed erosion in the Narayani River basin (draining central Nepal and presenting contrasted lithologic and geochemical signatures in its outcropping rocks and a wide variety of erosional processes and climaticconditions) to assess the relative contributions of erosion processes to the annual sediment export. By combining acoustic Doppler current profiler measurements with depth profiles and daily surface samplings of the suspended load, we propose a simplified model to precisely calculate sediment fluxes at the basin outlet. We estimate an equivalent erosion rate of 1:8+0:35-0:2 mm/year for the year 2010, similar to the average value of 1:6+0:35-0:2 mm/year estimated from 15 years of records and long-term (textasciitildeky) denudation rates of 1.7 mm/year derived from cosmogenic nuclides. The stability of erosion is attributed to efficient bufferingbehavior and spatial integration in the drainage system. Strong relations between rainfall events and the sediment export suggest that the system is mainly supply limited. Combining physical calculation of sediment fluxes with grain size analyses and geochemical tracers (hydroxyl isotopic compositions, carbonate contents, and total organic carbon content), we estimate that glacial and soil erosion do not contribute more than 10% and a few percentage, respectively, to the total budget and are only detectable during premonsoon and early monsoon periods. During the monsoon, erosion by landslides and mass wasting events overwhelms the sediment budget, confirming the dominant role of these erosional processes in activemountain chains. |
2017
|
Charreau, J., Saint-Carlier, D., Dominguez, S., Lavé, J., Blard, P. H., Avouac, J. P., Jolivet, M., Chen, Y., Wang, S. L., Brown, N. D., Malatesta, L. C., Rhodes, E., Team, ASTER Denudation outpaced by crustal thickening in the eastern Tianshan (Article de journal) Dans: Earth and Planetary Science Letters, vol. 479, p. 179–191, 2017. @article{Charreau_etal2017,
title = {Denudation outpaced by crustal thickening in the eastern Tianshan},
author = {J. Charreau and D. Saint-Carlier and S. Dominguez and J. Lav\'{e} and P. H. Blard and J. P. Avouac and M. Jolivet and Y. Chen and S. L. Wang and N. D. Brown and L. C. Malatesta and E. Rhodes and ASTER Team},
doi = {10.1016/j.epsl.2017.09.025},
year = {2017},
date = {2017-01-01},
journal = {Earth and Planetary Science Letters},
volume = {479},
pages = {179--191},
abstract = {The modern high topography of the Tianshan resulted from the reactivation of a Paleozoic orogenic belt by the India/Asia collision. Today, the range exhibits tectonically active forelands and intermontane basins. Based on quantitative morphotectonic observations and age constraints derived from cosmogenic 10Be dating, single-grain post-infrared infrared stimulated luminescence (p-IR IRSL) dating and modeling of fault scarp degradation, we quantify the deformation in the Nalati and Bayanbulak intermontane basins in the central Eastern Tianshan. Our results indicate that at least 1.4mm/yr of horizontal crustal shortening is accommodated within these two basins. This shortening represents over 15% of the 8.5 textpm0.5mm/yr total shortening rate across the entire range at this longitude. This shortening rate implies that the Eastern Central Tianshan is thickening at a mean rate of �`u1.4mm/yr, a rate that is significantly higher than the average denudation rate of 0.14mm/yr derived from our cosmogenic analysis. This discrepancy suggests that the Tianshan range has not yet reached a steady-state topography and remains in a transient state of topographic growth, most likely due to limited denudation rates driven by the arid climate of Central Asia.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The modern high topography of the Tianshan resulted from the reactivation of a Paleozoic orogenic belt by the India/Asia collision. Today, the range exhibits tectonically active forelands and intermontane basins. Based on quantitative morphotectonic observations and age constraints derived from cosmogenic 10Be dating, single-grain post-infrared infrared stimulated luminescence (p-IR IRSL) dating and modeling of fault scarp degradation, we quantify the deformation in the Nalati and Bayanbulak intermontane basins in the central Eastern Tianshan. Our results indicate that at least 1.4mm/yr of horizontal crustal shortening is accommodated within these two basins. This shortening represents over 15% of the 8.5 textpm0.5mm/yr total shortening rate across the entire range at this longitude. This shortening rate implies that the Eastern Central Tianshan is thickening at a mean rate of �`u1.4mm/yr, a rate that is significantly higher than the average denudation rate of 0.14mm/yr derived from our cosmogenic analysis. This discrepancy suggests that the Tianshan range has not yet reached a steady-state topography and remains in a transient state of topographic growth, most likely due to limited denudation rates driven by the arid climate of Central Asia. |
Lupker, M., Lavé, J., France-Lanord, C., Christl, M., Bourl`es, D., Carcaillet, J., Maden, C., Wieler, R., Rahman, M., Bezbaruah, D., Xiaohan, L. 10Be systematics in the Tsangpo-Brahmaputra catchment : the cosmogenic nuclide legacy of the eastern Himalayan syntaxis (Article de journal) Dans: Earth Surface Dynamics, vol. 5, p. 429–449, 2017. @article{Lupker_etal2017,
title = {10Be systematics in the Tsangpo-Brahmaputra catchment : the cosmogenic nuclide legacy of the eastern Himalayan syntaxis},
author = {M. Lupker and J. Lav\'{e} and C. France-Lanord and M. Christl and D. Bourl`es and J. Carcaillet and C. Maden and R. Wieler and M. Rahman and D. Bezbaruah and L. Xiaohan},
doi = {10.5194/esurf-5-429-2017},
year = {2017},
date = {2017-01-01},
journal = {Earth Surface Dynamics},
volume = {5},
pages = {429--449},
abstract = {The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to \> 4mmyr-1) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs 150 km downstream of the Namche Barwa--Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo-Brahmaputra sediments, provides constraints on the denudation rates in that region. These denudation estimates range from ca. 2 to 5mmyr-1 for the entire syntaxis and ca. 4 to 28mmyr-1 for the NBGPm, which is significantly higher than other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt yr-1 equivalent to a denudation rate between 0.7 and 1.2mmyr-1 for the entire catchment},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to > 4mmyr-1) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs 150 km downstream of the Namche Barwa--Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo-Brahmaputra sediments, provides constraints on the denudation rates in that region. These denudation estimates range from ca. 2 to 5mmyr-1 for the entire syntaxis and ca. 4 to 28mmyr-1 for the NBGPm, which is significantly higher than other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt yr-1 equivalent to a denudation rate between 0.7 and 1.2mmyr-1 for the entire catchment |
Malatesta, L. C., Avouac, J. P., Brown, N. D., Breitenbach, S. F. M., Pan, J., Chevalier, M. L., Rhodes, E., Saint-Carlier, D., Zhang, W., Charreau, J., Lavé, J., Blard, P. H. Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate-driven aggradation-incision cycles (Article de journal) Dans: Basin Research, vol. 30, no. 4, p. 613–635, 2017. @article{Malatesta_etal2017,
title = {Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate-driven aggradation-incision cycles},
author = {L. C. Malatesta and J. P. Avouac and N. D. Brown and S. F. M. Breitenbach and J. Pan and M. L. Chevalier and E. Rhodes and D. Saint-Carlier and W. Zhang and J. Charreau and J. Lav\'{e} and P. H. Blard},
year = {2017},
date = {2017-01-01},
journal = {Basin Research},
volume = {30},
number = {4},
pages = {613--635},
abstract = {Transient sediment storage and mixing of deposits of various ages during transport across alluvial piedmonts alter the clastic sedimentary record. We quantify buffering and mixing during cycles of aggradation--incision in the north piedmont of the Eastern Tian Shan. We complement existing chronologic data with 20 new luminescence ages and one cosmogenic radionuclide age of terrace abandonment and alluvial aggradation. Over the last 0.5 Myr, the piedmont deeply incised and aggraded many times per 100 kyr. Aggradation is driven by an increased flux of glacial sediment accumulated in the high range and flushed onto the piedmont by greater water discharge at stadial--interstadial transitions. After this sediment is evacuated from the high range, the reduced input sediment flux results in fluvial incision of the piedmont as fast as 9 cm year−1 and to depths up to 330 m. The timing of incision onset is different in each river and does not directly reflect climate forcing but the necessary time for the evacuation of glacial sediment from the high range. A significant fraction of sediments evacuated from the high range is temporarily stored on the piedmont before a later incision phase delivers it to the basin. Coarse sediments arrive in the basin with a lag of at least 7--14 kyrs between the first evacuation from the mountain and later basinward transport. The modern output flux of coarse sediments from the piedmont contains a significant amount of recycled material that was deposited on the piedmont as early as the Middle Pleistocene. Variations in temperature and moisture delivered by the Westerlies are the likely cause of repeated aggradation--incision cycles in the north piedmont instead of monsoonal precipitation. The arrival of the gravel front into the proximal basin is delayed relative to the fine‐grained load and both are separated by a hiatus. This work shows, based on field observations and data, how sedimentary systems respond to climatic perturbations, and how sediment recycling and mixing can ensue.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Transient sediment storage and mixing of deposits of various ages during transport across alluvial piedmonts alter the clastic sedimentary record. We quantify buffering and mixing during cycles of aggradation--incision in the north piedmont of the Eastern Tian Shan. We complement existing chronologic data with 20 new luminescence ages and one cosmogenic radionuclide age of terrace abandonment and alluvial aggradation. Over the last 0.5 Myr, the piedmont deeply incised and aggraded many times per 100 kyr. Aggradation is driven by an increased flux of glacial sediment accumulated in the high range and flushed onto the piedmont by greater water discharge at stadial--interstadial transitions. After this sediment is evacuated from the high range, the reduced input sediment flux results in fluvial incision of the piedmont as fast as 9 cm year−1 and to depths up to 330 m. The timing of incision onset is different in each river and does not directly reflect climate forcing but the necessary time for the evacuation of glacial sediment from the high range. A significant fraction of sediments evacuated from the high range is temporarily stored on the piedmont before a later incision phase delivers it to the basin. Coarse sediments arrive in the basin with a lag of at least 7--14 kyrs between the first evacuation from the mountain and later basinward transport. The modern output flux of coarse sediments from the piedmont contains a significant amount of recycled material that was deposited on the piedmont as early as the Middle Pleistocene. Variations in temperature and moisture delivered by the Westerlies are the likely cause of repeated aggradation--incision cycles in the north piedmont instead of monsoonal precipitation. The arrival of the gravel front into the proximal basin is delayed relative to the fine‐grained load and both are separated by a hiatus. This work shows, based on field observations and data, how sedimentary systems respond to climatic perturbations, and how sediment recycling and mixing can ensue. |
Martin, L. C. P., Blard, P. H., Balco, G., Lavé, J., Delunel, R., Lifton, N., Laurent, V. The CREp program and the ICE-D production rate calibration database: A fully parameterizable and updated online tool to compute cosmic- ray exposure ages (Article de journal) Dans: Quaternary Geochronology, vol. 38, p. 25–49, 2017. @article{Martin_etal2017,
title = {The CREp program and the ICE-D production rate calibration database: A fully parameterizable and updated online tool to compute cosmic- ray exposure ages},
author = {L. C. P. Martin and P. H. Blard and G. Balco and J. Lav\'{e} and R. Delunel and N. Lifton and V. Laurent},
doi = {10.1016/j.quageo.2016.11.006},
year = {2017},
date = {2017-01-01},
journal = {Quaternary Geochronology},
volume = {38},
pages = {25--49},
abstract = {Over the last decades, cosmogenic exposure dating has permitted major advances in many fields of Earth surface sciences and particularly in paleoglaciology. Yet, exposure age calculation remains a complicated and dense procedure. It requires numerous choices of parameterization and the use of an accurate production rate.This study describes the CREp program (http://crep.crpg.cnrs-nancy.fr) and the ICE-D production rate online database (http://calibration.ice-d.org). This system is designed so that the CREp calculator will automatically reflect the current state of this global calibration database production rate, ICE-D. ICE-D will be regularly updated in order to incorporate new calibration data and reflect the current state of the available literature. CREp is a Octave/Matlabtextcopyright online code that computes Cosmic Ray Exposure (CRE) ages for 3He and 10Be. A stand-alone version of the CREp code is also released with the present article. Note however that only the online version is connected to the online database ICE-D. The CREp program offers the possibility to calculate ages with two scaling models: i.e. the empirical Lal-Stone time-dependent model (Balco et al., 2008; Lal, 1991; Stone, 2000) with the muon parameters of Braucher et al. (2011), and the Lifton-Sato-Dunai (LSD) theoretical model (Lifton et al., 2014). The default atmosphere model is the ERA-40 data-base (Uppala et al., 2005), but one may also use the standard atmosphere for comparison (N.O.A.A, 1976). To perform the time-dependent correction, users may import their own geomagnetic database for paleomagnetic corrections or opt for one of the three proposed datasets (Lifton, 2016; Lifton et al., 2014; Muscheler et al., 2005). For the important choice of the production rate, CREp is linked to a database of production rate calibration data that is part of the ICE-D (Informal Cosmogenic-nuclide Exposure-age Database) project (http://calibration.ice-d.org). This database includes published empirical calibration rate studies that are publicly available at present, comprising those of the CRONUS-Earth and CRONUS-EU projects, as well as studies from other projects. In the present study, the efficacy of the different scaling models has alsobeen evaluated looking at the statistical dispersion of the computed Sea Level High Latitude (SLHL) production rates. Lal/Stone and LSD models have comparable efficacies, and the impact of the tested atmospheric model and the geomagnetic database is also limited. Users however have several possibilities to select the production rate: 1) using a worldwide mean value, 2) a regionally averaged value (not available in regions with no data), 3) a local unique value, which can be chosen among the existing dataset or imported by the user, or 4) any combination ofmultiple calibration data. If a global mean is chosen, the 1s uncertainty arising from the production rate is about 5% for 10 Be and 10% for 3 He. If a regional production rate is picked, these uncertainties are potentially lower.CREp is able to calculate a large number of ages in a reasonable time (typically\<30 s for 50 samples). The user may export a summary table of the computed ages and the density probability function associated with each age (in the form of a spreadsheet).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Over the last decades, cosmogenic exposure dating has permitted major advances in many fields of Earth surface sciences and particularly in paleoglaciology. Yet, exposure age calculation remains a complicated and dense procedure. It requires numerous choices of parameterization and the use of an accurate production rate.This study describes the CREp program (http://crep.crpg.cnrs-nancy.fr) and the ICE-D production rate online database (http://calibration.ice-d.org). This system is designed so that the CREp calculator will automatically reflect the current state of this global calibration database production rate, ICE-D. ICE-D will be regularly updated in order to incorporate new calibration data and reflect the current state of the available literature. CREp is a Octave/Matlabtextcopyright online code that computes Cosmic Ray Exposure (CRE) ages for 3He and 10Be. A stand-alone version of the CREp code is also released with the present article. Note however that only the online version is connected to the online database ICE-D. The CREp program offers the possibility to calculate ages with two scaling models: i.e. the empirical Lal-Stone time-dependent model (Balco et al., 2008; Lal, 1991; Stone, 2000) with the muon parameters of Braucher et al. (2011), and the Lifton-Sato-Dunai (LSD) theoretical model (Lifton et al., 2014). The default atmosphere model is the ERA-40 data-base (Uppala et al., 2005), but one may also use the standard atmosphere for comparison (N.O.A.A, 1976). To perform the time-dependent correction, users may import their own geomagnetic database for paleomagnetic corrections or opt for one of the three proposed datasets (Lifton, 2016; Lifton et al., 2014; Muscheler et al., 2005). For the important choice of the production rate, CREp is linked to a database of production rate calibration data that is part of the ICE-D (Informal Cosmogenic-nuclide Exposure-age Database) project (http://calibration.ice-d.org). This database includes published empirical calibration rate studies that are publicly available at present, comprising those of the CRONUS-Earth and CRONUS-EU projects, as well as studies from other projects. In the present study, the efficacy of the different scaling models has alsobeen evaluated looking at the statistical dispersion of the computed Sea Level High Latitude (SLHL) production rates. Lal/Stone and LSD models have comparable efficacies, and the impact of the tested atmospheric model and the geomagnetic database is also limited. Users however have several possibilities to select the production rate: 1) using a worldwide mean value, 2) a regionally averaged value (not available in regions with no data), 3) a local unique value, which can be chosen among the existing dataset or imported by the user, or 4) any combination ofmultiple calibration data. If a global mean is chosen, the 1s uncertainty arising from the production rate is about 5% for 10 Be and 10% for 3 He. If a regional production rate is picked, these uncertainties are potentially lower.CREp is able to calculate a large number of ages in a reasonable time (typically<30 s for 50 samples). The user may export a summary table of the computed ages and the density probability function associated with each age (in the form of a spreadsheet). |
Puchol, N., Blard, P. H., Pik, R., Tibari, B., Lavé, J. Variability of magmatic and cosmogenic 3 He in Ethiopian river sands of detrital pyroxenes: Impact on denudation rate determinations (Article de journal) Dans: Chemical Geology, vol. 448, p. 13–25, 2017. @article{Puchol_etal2017,
title = {Variability of magmatic and cosmogenic 3 He in Ethiopian river sands of detrital pyroxenes: Impact on denudation rate determinations},
author = {N. Puchol and P. H. Blard and R. Pik and B. Tibari and J. Lav\'{e}},
doi = {0.1016/j.chemgeo.2016.10.033},
year = {2017},
date = {2017-01-01},
journal = {Chemical Geology},
volume = {448},
pages = {13--25},
abstract = {In-situ cosmogenic 3He is a robust tool for determining denudation rates or exposure ages of lavas bearing mafic phenocrysts. However, analyses are often complicated by the presence of several helium sources. In particular, in old magmatic rocks with high radiogenic 4He contents, discriminating cosmogenic 3He from magmatic 3He is not straightforward since these varieties may vary largely between aliquots. We sampled sands from the Tekeze and Mile rivers, both draining the basaltic Ethiopian highlands, an area where erosion patterns are intimately linked to the development of the Western Afar margin and to heterogeneous monsoon precipitation. From each river we analyzed textasciitilde15 aliquots of pyroxenes having variable grain sizes (0.3 mm up to N 1 mm). The total 3 He is both higher and more scattered in the bigger grains. Crushing of these largest grains and subsequent melting of the powder tends to produce more homogeneous 3 He values, suggesting that magmatic 3He hosted in inclusions is responsible for most of the inter-aliquot variability. We also performed a Monte Carlo simulation based on a numerical denudation model of the two watersheds. The simulation confirms that cosmogenic3 He variability cannot be responsible for the observed scatter since the cosmogenic 3 He variability is averaged away and unobservable in aliquots of textasciitilde200 grains. A compilation of previously published data also indicates that magmatic helium can be significantly variable, even between pre-crushed aliquots. Hence, magmatic helium, unlike cosmogenic 3 He, is highly variable, even in the case of aliquots of hundreds of grains. We suggest this is due to a strong nugget effect, possibly due to large fluid (or melt)-inclusions contained in phenocrysts.In addition, the fact that small and big grains have comparable radiogenic 4 He concentrations suggests that grain fragmentation during river transport is responsible for the lower magmatic helium content of the smallest grains. Therefore, one should preferably use small grain (0.2--0.5 mm) granulometry for in-situ cosmogenic 3 He analysis in mafic phenocrysts. Using the measured cosmogenic3 He, we calculate basin-averaged denudation rates of 70 textpm 20 and 57 textpm 5mmkyr − 1 , for the Mile and for the Tekeze river, respectively. These values are coherent with long-term denudation rates previously proposed from low-temperature thermochronology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In-situ cosmogenic 3He is a robust tool for determining denudation rates or exposure ages of lavas bearing mafic phenocrysts. However, analyses are often complicated by the presence of several helium sources. In particular, in old magmatic rocks with high radiogenic 4He contents, discriminating cosmogenic 3He from magmatic 3He is not straightforward since these varieties may vary largely between aliquots. We sampled sands from the Tekeze and Mile rivers, both draining the basaltic Ethiopian highlands, an area where erosion patterns are intimately linked to the development of the Western Afar margin and to heterogeneous monsoon precipitation. From each river we analyzed textasciitilde15 aliquots of pyroxenes having variable grain sizes (0.3 mm up to N 1 mm). The total 3 He is both higher and more scattered in the bigger grains. Crushing of these largest grains and subsequent melting of the powder tends to produce more homogeneous 3 He values, suggesting that magmatic 3He hosted in inclusions is responsible for most of the inter-aliquot variability. We also performed a Monte Carlo simulation based on a numerical denudation model of the two watersheds. The simulation confirms that cosmogenic3 He variability cannot be responsible for the observed scatter since the cosmogenic 3 He variability is averaged away and unobservable in aliquots of textasciitilde200 grains. A compilation of previously published data also indicates that magmatic helium can be significantly variable, even between pre-crushed aliquots. Hence, magmatic helium, unlike cosmogenic 3 He, is highly variable, even in the case of aliquots of hundreds of grains. We suggest this is due to a strong nugget effect, possibly due to large fluid (or melt)-inclusions contained in phenocrysts.In addition, the fact that small and big grains have comparable radiogenic 4 He concentrations suggests that grain fragmentation during river transport is responsible for the lower magmatic helium content of the smallest grains. Therefore, one should preferably use small grain (0.2--0.5 mm) granulometry for in-situ cosmogenic 3 He analysis in mafic phenocrysts. Using the measured cosmogenic3 He, we calculate basin-averaged denudation rates of 70 textpm 20 and 57 textpm 5mmkyr − 1 , for the Mile and for the Tekeze river, respectively. These values are coherent with long-term denudation rates previously proposed from low-temperature thermochronology. |
Puchol, N., Charreau, J., Blard, P. H., Lavé, J., Dominguez, S., Pik, R., Saint-Carlier, D., Team, ASTER Limited impact of Quaternary glaciations on denudation rates in Central Asia (Article de journal) Dans: GSA Bulletin, vol. 129, no. 3-4, p. 479–499, 2017. @article{Puchol_etal2017_2,
title = {Limited impact of Quaternary glaciations on denudation rates in Central Asia},
author = {N. Puchol and J. Charreau and P. H. Blard and J. Lav\'{e} and S. Dominguez and R. Pik and D. Saint-Carlier and ASTER Team},
doi = {10.1130/B31475.1},
year = {2017},
date = {2017-01-01},
journal = {GSA Bulletin},
volume = {129},
number = {3-4},
pages = {479--499},
abstract = {Because of its essential role in coupling climate and tectonics, denudationis a key parameter when constraining the history of Earthtextquoterightssurface. This is particularly true at the Pliocene-Pleistocene transition,and the potential impact of the onset of Quaternary glaciationsremains strongly debated. In the present study, we measured in situcosmogenic 10Be within continuous late Cenozoic sedimentary sectionsthat had already been dated using magnetostratigraphy. Thenew data were obtained from four sedimentary basins in the northernand southern Tianshan range (Central Asia). We first thoroughly discusshow in situ cosmogenic 10Be concentrations can be corrected forradioactive decay and for the contribution of postdepositional cosmogenicaccumulation to derive the paleo--denudation rates. Our analysisshows that, in the four sedimentary records, the potential bias remainslow enough to consider the derived denudation rates reliable.The four records, although likely influenced by local particularitiesdue to lithological heterogeneity and local tectonics, display similartrends of continuously increasing denudation between ca. 9 Ma andthe present. These rates have remained relatively high but steadysince 4 Ma, textasciitilde1.5 m.y. before the onset of the Quaternary glacial cycles.Though the rejuvenation of the Tianshan range since 11 Ma may explainmost of the progressive increase (texttimes5) in denudation, our datasuggest that the Quaternary glaciations had only a limited impact ondenudation in the Tianshan. Our data, however, indicate an increasein the spatial and high-frequency variability (\<1 m.y.) of the denudationrates between 3 and 1 Ma. This may correspond to a transientreadjustment of the landscape in response to the onset of Quaternaryglacial cycles},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Because of its essential role in coupling climate and tectonics, denudationis a key parameter when constraining the history of Earthtextquoterightssurface. This is particularly true at the Pliocene-Pleistocene transition,and the potential impact of the onset of Quaternary glaciationsremains strongly debated. In the present study, we measured in situcosmogenic 10Be within continuous late Cenozoic sedimentary sectionsthat had already been dated using magnetostratigraphy. Thenew data were obtained from four sedimentary basins in the northernand southern Tianshan range (Central Asia). We first thoroughly discusshow in situ cosmogenic 10Be concentrations can be corrected forradioactive decay and for the contribution of postdepositional cosmogenicaccumulation to derive the paleo--denudation rates. Our analysisshows that, in the four sedimentary records, the potential bias remainslow enough to consider the derived denudation rates reliable.The four records, although likely influenced by local particularitiesdue to lithological heterogeneity and local tectonics, display similartrends of continuously increasing denudation between ca. 9 Ma andthe present. These rates have remained relatively high but steadysince 4 Ma, textasciitilde1.5 m.y. before the onset of the Quaternary glacial cycles.Though the rejuvenation of the Tianshan range since 11 Ma may explainmost of the progressive increase (texttimes5) in denudation, our datasuggest that the Quaternary glaciations had only a limited impact ondenudation in the Tianshan. Our data, however, indicate an increasein the spatial and high-frequency variability (<1 m.y.) of the denudationrates between 3 and 1 Ma. This may correspond to a transientreadjustment of the landscape in response to the onset of Quaternaryglacial cycles |
2016
|
Bosia, C., Chabaux, F., Pelt, E., France-Lanord, C., Morin, G., Lavé, J., Stille, P. U--Th--Ra variations in Himalayan river sediments (Gandak river, India): Weathering fractionation and/or grain-size sorting? (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 193, p. 176–196, 2016. @article{Bosia_etal2016,
title = {U--Th--Ra variations in Himalayan river sediments (Gandak river, India): Weathering fractionation and/or grain-size sorting?},
author = {C. Bosia and F. Chabaux and E. Pelt and C. France-Lanord and G. Morin and J. Lav\'{e} and P. Stille},
doi = {10.1016/j.gca.2016.08.026},
year = {2016},
date = {2016-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {193},
pages = {176--196},
abstract = {Understanding the origin of U--Th--Ra variations in the Ganga river sediments is a prerequisite for correctly using U-series nuclides to constrain the sediment transport times in Himalayan rivers. For this purpose, U, Th, and Ra concentrations, along with 238U--234U--230Th--226Ra radioactive disequilibria, were analyzed in bank, bedload and suspended sediments from the Gandak river, one of the main tributaries of the Ganga river. The data confirm that U and Th budgets of the Himalayan sediments are significantly influenced by minor resistant minerals, such as zircon, garnet and Ti-bearing minerals, the dissolution of which required the use of a high-pressure acid digestion process. Most importantly, the results indicate that the variations in (238U/232Th) and (230Th/232Th) activity ratios and 238U--234U--230Th--226Ra disequilibria in sediments along the river alluvial plain mainly reflect modifications in the mineralogical and grain-size compositions rather than the degree of weathering during transport. The (238U/232Th) and (230Th/232Th) activity ratios in the bank and bed sediments are related to variations in the minor primary minerals strongly enriched in U and Th (i.e., zircon, REE-bearing minerals and Ti-bearing minerals), whereas the activity ratios in the suspended load are related to variations in the proportions of clay, Fe-oxyhydroxides and the silt-sand fraction, which contains U- and Th-bearing minor minerals. The data also indicate that 238U--234U--230Th--226Ra disequilibria are strongly influenced by secondary mineral phases : the 230Th budget is likely mainly controlled by Fe-oxyhydroxides, and the 226Ra budget is likely mainly controlled by clay minerals. Therefore, the variations in the 238U--234U--230Th--232Th system in the sediments of the Gandak river cannot simply be interpreted as the result of fractionation due to chemical transformation of the bulk sediment during its transport within the alluvial plain and/or the result of radioactive decay. Consequently, they cannot be used to infer long sediment transport times within the Gandak plain (10--100 ka), as previously proposed. Such analytical and interpretative artifacts are certainly not specific to the present study on the Gandak basin. These issues will certainly be encountered anytime this technique is applied to alluvial systems in which the U and Th budgets of the sediments are influenced by textquotelefttextquoteleftheavytextquoterighttextquoteright minerals that can be sorted during the transport of sediments within the plain.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Understanding the origin of U--Th--Ra variations in the Ganga river sediments is a prerequisite for correctly using U-series nuclides to constrain the sediment transport times in Himalayan rivers. For this purpose, U, Th, and Ra concentrations, along with 238U--234U--230Th--226Ra radioactive disequilibria, were analyzed in bank, bedload and suspended sediments from the Gandak river, one of the main tributaries of the Ganga river. The data confirm that U and Th budgets of the Himalayan sediments are significantly influenced by minor resistant minerals, such as zircon, garnet and Ti-bearing minerals, the dissolution of which required the use of a high-pressure acid digestion process. Most importantly, the results indicate that the variations in (238U/232Th) and (230Th/232Th) activity ratios and 238U--234U--230Th--226Ra disequilibria in sediments along the river alluvial plain mainly reflect modifications in the mineralogical and grain-size compositions rather than the degree of weathering during transport. The (238U/232Th) and (230Th/232Th) activity ratios in the bank and bed sediments are related to variations in the minor primary minerals strongly enriched in U and Th (i.e., zircon, REE-bearing minerals and Ti-bearing minerals), whereas the activity ratios in the suspended load are related to variations in the proportions of clay, Fe-oxyhydroxides and the silt-sand fraction, which contains U- and Th-bearing minor minerals. The data also indicate that 238U--234U--230Th--226Ra disequilibria are strongly influenced by secondary mineral phases : the 230Th budget is likely mainly controlled by Fe-oxyhydroxides, and the 226Ra budget is likely mainly controlled by clay minerals. Therefore, the variations in the 238U--234U--230Th--232Th system in the sediments of the Gandak river cannot simply be interpreted as the result of fractionation due to chemical transformation of the bulk sediment during its transport within the alluvial plain and/or the result of radioactive decay. Consequently, they cannot be used to infer long sediment transport times within the Gandak plain (10--100 ka), as previously proposed. Such analytical and interpretative artifacts are certainly not specific to the present study on the Gandak basin. These issues will certainly be encountered anytime this technique is applied to alluvial systems in which the U and Th budgets of the sediments are influenced by textquotelefttextquoteleftheavytextquoterighttextquoteright minerals that can be sorted during the transport of sediments within the plain. |
Cassel, M., Piégay, H., Lavé, J. Effects of transport and insertion of radio frequency identification (RFID) transponders on resistance and shape of natural and synthetic pebbles: applications for riverine and coastal bedload tracking. (Article de journal) Dans: Earth Surface and Processes and Landforms, 2016. @article{Cassel_etal2016,
title = {Effects of transport and insertion of radio frequency identification (RFID) transponders on resistance and shape of natural and synthetic pebbles: applications for riverine and coastal bedload tracking.},
author = {M. Cassel and H. Pi\'{e}gay and J. Lav\'{e}},
year = {2016},
date = {2016-01-01},
journal = {Earth Surface and Processes and Landforms},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Hossler, T., Bollinger, L., Sapkota, S. N., Lavé, J., Gupta, R. M., Kandel, T. P. Surface ruptures of large Himalayan earthquakes in Western Nepal: Evidence along a reactivated strand of the Main Boundary Thrust (Article de journal) Dans: Earth and Planetary Science Letters, vol. 434, p. 187–196, 2016. @article{Hossler_etal2016,
title = {Surface ruptures of large Himalayan earthquakes in Western Nepal: Evidence along a reactivated strand of the Main Boundary Thrust},
author = {T. Hossler and L. Bollinger and S. N. Sapkota and J. Lav\'{e} and R. M. Gupta and T. P. Kandel},
doi = {10.1016/j.epsl.2015.11.042},
year = {2016},
date = {2016-01-01},
journal = {Earth and Planetary Science Letters},
volume = {434},
pages = {187--196},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Saint-Carlier, D., Charreau, J., Lavé, J., Blard, P. H., Dominguez, S., Avouac, J. P., Shenli, W., Team, ASTER Major temporal variations in shortening rate absorbed along a large active fold of the southeastern Tianshan piedmont (China) (Article de journal) Dans: Earth and Planetary Science Letters, vol. 434, p. 333–348, 2016. @article{Saint-Carlier_etal2016,
title = {Major temporal variations in shortening rate absorbed along a large active fold of the southeastern Tianshan piedmont (China)},
author = {D. Saint-Carlier and J. Charreau and J. Lav\'{e} and P. H. Blard and S. Dominguez and J. P. Avouac and W. Shenli and ASTER Team},
doi = {10.1016/j.epsl.2015.11.041},
year = {2016},
date = {2016-01-01},
journal = {Earth and Planetary Science Letters},
volume = {434},
pages = {333--348},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2015
|
Lavé, J. Landscape inversion by stream piracy (Article de journal) Dans: Nature, News & Views, vol. 520, p. 442–443, 2015. @article{Lav2015,
title = {Landscape inversion by stream piracy},
author = {J. Lav\'{e}},
year = {2015},
date = {2015-01-01},
journal = {Nature, News \& Views},
volume = {520},
pages = {442--443},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Martin, L. C. P., Blard, P. H., Lavé, J., Braucher, R., Lupker, M., Condom, T., Charreau, J., Mariotti, V., Team., ASTER, Davy, E. In situ cosmogenic 10 Be production rate in the High Tropical Andes (Article de journal) Dans: Quaternary Geochronology, vol. 30, p. 54–68, 2015. @article{Martin_etal2015,
title = {In situ cosmogenic 10 Be production rate in the High Tropical Andes},
author = {L. C. P. Martin and P. H. Blard and J. Lav\'{e} and R. Braucher and M. Lupker and T. Condom and J. Charreau and V. Mariotti and ASTER Team. and E. Davy},
doi = {10.1016/j.quageo.2015.06.012},
year = {2015},
date = {2015-01-01},
journal = {Quaternary Geochronology},
volume = {30},
pages = {54--68},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2014
|
Blard, P. H., Lavé, J., Farley, K. A., Ramirez, V., Jimenez, N., Martin, L. C. P., Charreau, J., Tibari, B., Fornari, M. Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22textdegreeS) between 65 and 14 ka constrained by cosmogenic 3 He dating (Article de journal) Dans: Quaternary Science Reviews, vol. 82, p. 209–221, 2014. @article{Blard_etal2014,
title = {Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22textdegreeS) between 65 and 14 ka constrained by cosmogenic 3 He dating},
author = {P. H. Blard and J. Lav\'{e} and K. A. Farley and V. Ramirez and N. Jimenez and L. C. P. Martin and J. Charreau and B. Tibari and M. Fornari},
doi = {10.1016/j.yqres.2014.02.002},
year = {2014},
date = {2014-01-01},
journal = {Quaternary Science Reviews},
volume = {82},
pages = {209--221},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Dubille, M., Lavé, J. Rapid grain size coarsening at sandstone/ conglomerate transition: similar expression in Himalayanmodern rivers and Pliocenemolasse deposits (Article de journal) Dans: Basin Research, p. 1–17, 2014. @article{Dubille+Lav2014,
title = {Rapid grain size coarsening at sandstone/ conglomerate transition: similar expression in Himalayanmodern rivers and Pliocenemolasse deposits},
author = {M. Dubille and J. Lav\'{e}},
doi = {10.1111/bre.12071},
year = {2014},
date = {2014-01-01},
journal = {Basin Research},
pages = {1--17},
abstract = {Radical grain size changes between two main units of a sedimentary megacycle in a foreland basin are commonly interpreted to result from changes in tectonic activity or climate in the adjacent mountain range. In central Nepal, the Cenozoic Siwalik molasse deposits exposed in the frontal Himalayan folds are characterized by such a radical grain size transition. Locally gravel deposits completelyreplace sands in vertical succession over approximately a hundred metres, the median grain size (D50) displaying a sharp increase by a factor of ca. 100. Such a rapid gravel-sand transition (GST) is also observed in present-day river channels about 8--20 km downstream from the outlet of the Siwalik Range. The passage from gravel-bed channel reaches (proximal alluvial fans) to sand-bed channel reaches (distal alluvial fans) occurs within a few kilometres on the Gangetic Plain in central Nepal, and the D50 ratio between the two types of channels equals ca. 100. We propose that the dramatic and remarkably similar increase in grain size observed in the Neogene Siwalik series and along modern rivers in the Gangetic foreland basin, results from a similar hydraulic process, i.e. a grain sortingprocess during the selective deposition of the sediment load. The sudden appearance of gravels in the upper Siwalik series would be related to the crossing of this sorting transition during progressive southward migration of the gravel front, in response to continuous Himalayan orogen construction.And as a consequence, the GST would be diachronous by nature. This study demonstrates that an abrupt change in grain size does not necessarily relate to a change in tectonic or climatic forcing, but can simply arise from internal adjustment of the piedmont rivers to the deposition and run out of coarse bedload. It illustrates, in addition, the genesis of quartz-rich conglomerates in the Himalayan foreland through gravel selective deposition associated with differential weathering, abrasion processes and sediment recycling during thrust wedge advance and shortening of the foreland basin.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Radical grain size changes between two main units of a sedimentary megacycle in a foreland basin are commonly interpreted to result from changes in tectonic activity or climate in the adjacent mountain range. In central Nepal, the Cenozoic Siwalik molasse deposits exposed in the frontal Himalayan folds are characterized by such a radical grain size transition. Locally gravel deposits completelyreplace sands in vertical succession over approximately a hundred metres, the median grain size (D50) displaying a sharp increase by a factor of ca. 100. Such a rapid gravel-sand transition (GST) is also observed in present-day river channels about 8--20 km downstream from the outlet of the Siwalik Range. The passage from gravel-bed channel reaches (proximal alluvial fans) to sand-bed channel reaches (distal alluvial fans) occurs within a few kilometres on the Gangetic Plain in central Nepal, and the D50 ratio between the two types of channels equals ca. 100. We propose that the dramatic and remarkably similar increase in grain size observed in the Neogene Siwalik series and along modern rivers in the Gangetic foreland basin, results from a similar hydraulic process, i.e. a grain sortingprocess during the selective deposition of the sediment load. The sudden appearance of gravels in the upper Siwalik series would be related to the crossing of this sorting transition during progressive southward migration of the gravel front, in response to continuous Himalayan orogen construction.And as a consequence, the GST would be diachronous by nature. This study demonstrates that an abrupt change in grain size does not necessarily relate to a change in tectonic or climatic forcing, but can simply arise from internal adjustment of the piedmont rivers to the deposition and run out of coarse bedload. It illustrates, in addition, the genesis of quartz-rich conglomerates in the Himalayan foreland through gravel selective deposition associated with differential weathering, abrasion processes and sediment recycling during thrust wedge advance and shortening of the foreland basin. |
Gallo, F., Lavé, J. Evolution of a large landslide in the High Himalaya of central Nepal during the last half-century (Article de journal) Dans: Geomorphology, vol. 223, p. 20–32, 2014. @article{Gallo+Lav2014,
title = {Evolution of a large landslide in the High Himalaya of central Nepal during the last half-century},
author = {F. Gallo and J. Lav\'{e}},
doi = {10.1016/j.geomorph.2014.06.021},
year = {2014},
date = {2014-01-01},
journal = {Geomorphology},
volume = {223},
pages = {20--32},
abstract = {Episodic and catastrophic landslides are considered to be one of the main sources of sediment in the steep, mountainous landscapes of the Himalayas. However, the evolution of a single landslide through time and its contribution to erosional processes remain poorly constrained. In this study, we focus on a single, large(0.5 km 2 ) landslide in a small catchment on the southern flank of the Annapurnas in Nepal (the Khudi valley) in order to quantify its importance in the overall erosion of this steep Himalayan catchment. The evolution of the Saituti landslide has been continuously monitored by remote sensing for the past 46 years.During that period, the Saituti landslide displayed sustained activity, such that the area of the landslide scar increased by a factor of 4. This retrogressive failure, a consequence of several sporadic flank and crown collapses, has not been continuous. Rather, acceleration phases have alternated with more quiescent periods. Simultaneously, the upper edge moved upward by 900 m. Based on field evidence from recent activity (such as scarps and open tension cracks above the landslide) and on an analysis of slope angles, at least the next 500 m is expected to fail. Volume losses within the landslide were estimated from differences between digital elevation models (DEMs) and from changes in landslide area, using a calibrated power law relationship between landslide area and volume. Corresponding landslide-induced erosion rates at the scale of the whole Khudi catchment were found to be 2.6 textpm 0.9 mm/y for the past half-century. Those rates are similar to denudation rates obtained from sediment load measurements between 1999 and 2004. Those results, along with the lack of other major lands lides in the valley for the last 46 years,suggest that the Saituti landslide plays adominant role in the modern erosion of the High Himalayan Khudi catchment for the last years and possibly for the past few decades. We propose that continuous and sustained activity of a few major landslides over the past few decades mightrepresent a significant contribution to the erosion of the High Himalayan range. This long-lasting, landslide induced erosion should be taken into account when interpreting suspended load measurements, results from provenance analysis, or cosmogenic nuclides in river sand. Such processes should also be included in landscape evolution models when annual to secular problems are explored.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Episodic and catastrophic landslides are considered to be one of the main sources of sediment in the steep, mountainous landscapes of the Himalayas. However, the evolution of a single landslide through time and its contribution to erosional processes remain poorly constrained. In this study, we focus on a single, large(0.5 km 2 ) landslide in a small catchment on the southern flank of the Annapurnas in Nepal (the Khudi valley) in order to quantify its importance in the overall erosion of this steep Himalayan catchment. The evolution of the Saituti landslide has been continuously monitored by remote sensing for the past 46 years.During that period, the Saituti landslide displayed sustained activity, such that the area of the landslide scar increased by a factor of 4. This retrogressive failure, a consequence of several sporadic flank and crown collapses, has not been continuous. Rather, acceleration phases have alternated with more quiescent periods. Simultaneously, the upper edge moved upward by 900 m. Based on field evidence from recent activity (such as scarps and open tension cracks above the landslide) and on an analysis of slope angles, at least the next 500 m is expected to fail. Volume losses within the landslide were estimated from differences between digital elevation models (DEMs) and from changes in landslide area, using a calibrated power law relationship between landslide area and volume. Corresponding landslide-induced erosion rates at the scale of the whole Khudi catchment were found to be 2.6 textpm 0.9 mm/y for the past half-century. Those rates are similar to denudation rates obtained from sediment load measurements between 1999 and 2004. Those results, along with the lack of other major lands lides in the valley for the last 46 years,suggest that the Saituti landslide plays adominant role in the modern erosion of the High Himalayan Khudi catchment for the last years and possibly for the past few decades. We propose that continuous and sustained activity of a few major landslides over the past few decades mightrepresent a significant contribution to the erosion of the High Himalayan range. This long-lasting, landslide induced erosion should be taken into account when interpreting suspended load measurements, results from provenance analysis, or cosmogenic nuclides in river sand. Such processes should also be included in landscape evolution models when annual to secular problems are explored. |
Puchol, N., Lavé, J., Lupker, M., Blard, P. H., Gallo, F., France-Lanord, C., Team., ASTER Grain-size dependent concentration of cosmogenic 10 Be and erosion dynamics in a landslide-dominated Himalayan watershed (Article de journal) Dans: Geomorphology, vol. 224, p. 55–68, 2014. @article{Puchol_etal2014,
title = {Grain-size dependent concentration of cosmogenic 10 Be and erosion dynamics in a landslide-dominated Himalayan watershed},
author = {N. Puchol and J. Lav\'{e} and M. Lupker and P. H. Blard and F. Gallo and C. France-Lanord and ASTER Team.},
doi = {10.1016/j.geomorph.2014.06.019},
year = {2014},
date = {2014-01-01},
journal = {Geomorphology},
volume = {224},
pages = {55--68},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Wilson, A., Lavé, J. Convergent evolution of abrading flow obstacles: Insights from analogue modelling of fluvial bedrock abrasion by coarse bedload (Article de journal) Dans: Geomorphology, vol. 208, p. 207–224, 2014. @article{Wilson+Lav2014,
title = {Convergent evolution of abrading flow obstacles: Insights from analogue modelling of fluvial bedrock abrasion by coarse bedload},
author = {A. Wilson and J. Lav\'{e}},
doi = {10.1016/j.geomorph.2013.11.024},
year = {2014},
date = {2014-01-01},
journal = {Geomorphology},
volume = {208},
pages = {207--224},
abstract = {Upstream-facing convex surfaces (UFCS) are formed by bedload abrasion in bedrock rivers and indicate the recent, significant action of bedload abrasion in causing channel incision. Beyond this, little is known of the dynamics of UFCS and the effect of substrate and bedload properties on rates and distribution of bedload abrasion for these bed roughness elements. Grain size populations from 1 to 8 cm (b-axis, in 1- or 2-cm bin widths) were used to bombard preshaped marble and limestone targets bolted to the base of an annular flume. The control of initial shape and lithology of the target and the erodent grain size and lithology were investigated by monitoring the evolution of the target form using laser scanning at predefined time intervals. Eleven experiment suites were carried out containing three initial target shapes constructed from two lithologies, four bedload (erodent) grain sizes of either granodiorites or limestone, or clear water flow. All 10 targets abraded by bedload evolved from their initial form into a steady state (time invariant) form, producing UFCSs. Steady state forms were closely similar for all targets despite different initial conditions. Bedload grain size has a strong control on this equilibrium form, related to the transit path of the grains when moving over the target, whilst initial target form has only a weak control. Steady state morphology is achieved more rapidly with harder erodent bedload particles and/or softer targets. Upstream-facing convex surface stoss sides were characterised by a brighter, sugary, granular appearance on the rock-forming grain scale. Increasing erodent grain size, for a fixed bedload mass, increased the bulk abrasion rate at fixed flow speed and discharge. No detectable erosion occurred for a limestone block in clear water flows under the same flow conditions, indicating solution and cavitation were insignificant mechanisms of erosion in this study. During the experiment suites, suspended load abrasion was also found to be an insignificant mechanism in eroding lee or lateral sides. In natural settings, the initial formation of UFCSs can occur for homogenous and/or jointed substrates in close association with plucking or, alternatively, for heterogeneous substrates by variation in substrate erodibility.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Upstream-facing convex surfaces (UFCS) are formed by bedload abrasion in bedrock rivers and indicate the recent, significant action of bedload abrasion in causing channel incision. Beyond this, little is known of the dynamics of UFCS and the effect of substrate and bedload properties on rates and distribution of bedload abrasion for these bed roughness elements. Grain size populations from 1 to 8 cm (b-axis, in 1- or 2-cm bin widths) were used to bombard preshaped marble and limestone targets bolted to the base of an annular flume. The control of initial shape and lithology of the target and the erodent grain size and lithology were investigated by monitoring the evolution of the target form using laser scanning at predefined time intervals. Eleven experiment suites were carried out containing three initial target shapes constructed from two lithologies, four bedload (erodent) grain sizes of either granodiorites or limestone, or clear water flow. All 10 targets abraded by bedload evolved from their initial form into a steady state (time invariant) form, producing UFCSs. Steady state forms were closely similar for all targets despite different initial conditions. Bedload grain size has a strong control on this equilibrium form, related to the transit path of the grains when moving over the target, whilst initial target form has only a weak control. Steady state morphology is achieved more rapidly with harder erodent bedload particles and/or softer targets. Upstream-facing convex surface stoss sides were characterised by a brighter, sugary, granular appearance on the rock-forming grain scale. Increasing erodent grain size, for a fixed bedload mass, increased the bulk abrasion rate at fixed flow speed and discharge. No detectable erosion occurred for a limestone block in clear water flows under the same flow conditions, indicating solution and cavitation were insignificant mechanisms of erosion in this study. During the experiment suites, suspended load abrasion was also found to be an insignificant mechanism in eroding lee or lateral sides. In natural settings, the initial formation of UFCSs can occur for homogenous and/or jointed substrates in close association with plucking or, alternatively, for heterogeneous substrates by variation in substrate erodibility. |
2013
|
Blard, P. H., Braucher, R., Lavé, J., Bourl`es, D. Cosmogenic 10Be production rate calibrated against 3He in the high Tropical Andes (3800--4900m, 20--22◦ S) (Article de journal) Dans: Earth and Planetary Science Letters, vol. 382, p. 140–149, 2013. @article{Blard_etal2013,
title = {Cosmogenic 10Be production rate calibrated against 3He in the high Tropical Andes (3800--4900m, 20--22◦ S)},
author = {P. H. Blard and R. Braucher and J. Lav\'{e} and D. Bourl`es},
doi = {10.1016/j.epsl.2013.09.010},
year = {2013},
date = {2013-01-01},
journal = {Earth and Planetary Science Letters},
volume = {382},
pages = {140--149},
abstract = {Many geomorphologic applications,notably glacier chronologies,require improvements in both the precision and the accuracy of the cosmogenic dating tool.Of particular importance is the need to better constraint hespatial variability of the cosmogenic nuclides production rates at high elevation and low latitudes.One strategy that can be adopted for this is to couple absolute calibrations,from independently dated surfaces,with cross-calibration studies,performed by measuring several cosmogenic nuclides in the same rock.In the present study,were port the highest-elevation(\>4800m)cross-calibration published todate,comprising measurements of cosmogenic 3He and 10Be incogenetic pyroxene and quartz.The samples were collected from six dacitic moraine boulders,exposed from 32 to 65ka at 4820m on the flanks of the Uturuncu volcano(22◦S,67◦W),Southern Lipez(Bolivia).The samples yield are markably tight cluster of 3He--10Be production ratios, with a weighted mean of 33.3textpm0.9(1$sigma$).This production ratio is undistinguishable,with inuncertainties,from the 3He--10Be production ratio of 32.3textpm0.9 determined in the same mineral pair at lowel evation (1333m)by Amidon et al.(2009).These results agree at the 1$sigma$level and suggest that any hypothetical increase of the 3He--10Be production ratio in pyroxene and quartz is likely to be lower than 5% over this elevation range(1000--5000m).Moreover,the production ratio is almost insensitive to the Li content of the pyroxene(20to50ppmLi),suggesting that the cosmogenic thermal neutron production of 3He is very low in this setting.The high-elevation 3He--10Be production ratio is used in combination with a local determination of the 3He production rate in the high Central Altiplano(3800m)(Blard et al.,2013)to establish a local 10Be production rate of 30.0textpm1.4 atg−1yr−1at 3800m and 20◦S.After scaling to sea-level high latitude with the time-dependent Lal/Stone model,this yields a10Be production rate in quartz of 3.63textpm0.17 at g−1yr−1.Importantly, this rate can be used for high-precision geomorphologic dating,for example for determining glacial chronologies(1$sigma$\<4%)through 10Be dating of moraines in the high Tropical Andes.Any inaccuracy attached to the scaling model is canceled out when the calibration site is located close to the dated object.The same experiment was also undertaken in pyroxene and plagioclase from two andesitic boulders from the Tunupavolcano moraines,exposed at 3800m and 4200m.A3He--10Be production ratio of 35.9textpm1.3(1$sigma$)is obtained for this mineral pair,indicating that the 10Be production rate in plagioclase is about 8%lower than in quartz.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Many geomorphologic applications,notably glacier chronologies,require improvements in both the precision and the accuracy of the cosmogenic dating tool.Of particular importance is the need to better constraint hespatial variability of the cosmogenic nuclides production rates at high elevation and low latitudes.One strategy that can be adopted for this is to couple absolute calibrations,from independently dated surfaces,with cross-calibration studies,performed by measuring several cosmogenic nuclides in the same rock.In the present study,were port the highest-elevation(>4800m)cross-calibration published todate,comprising measurements of cosmogenic 3He and 10Be incogenetic pyroxene and quartz.The samples were collected from six dacitic moraine boulders,exposed from 32 to 65ka at 4820m on the flanks of the Uturuncu volcano(22◦S,67◦W),Southern Lipez(Bolivia).The samples yield are markably tight cluster of 3He--10Be production ratios, with a weighted mean of 33.3textpm0.9(1$sigma$).This production ratio is undistinguishable,with inuncertainties,from the 3He--10Be production ratio of 32.3textpm0.9 determined in the same mineral pair at lowel evation (1333m)by Amidon et al.(2009).These results agree at the 1$sigma$level and suggest that any hypothetical increase of the 3He--10Be production ratio in pyroxene and quartz is likely to be lower than 5% over this elevation range(1000--5000m).Moreover,the production ratio is almost insensitive to the Li content of the pyroxene(20to50ppmLi),suggesting that the cosmogenic thermal neutron production of 3He is very low in this setting.The high-elevation 3He--10Be production ratio is used in combination with a local determination of the 3He production rate in the high Central Altiplano(3800m)(Blard et al.,2013)to establish a local 10Be production rate of 30.0textpm1.4 atg−1yr−1at 3800m and 20◦S.After scaling to sea-level high latitude with the time-dependent Lal/Stone model,this yields a10Be production rate in quartz of 3.63textpm0.17 at g−1yr−1.Importantly, this rate can be used for high-precision geomorphologic dating,for example for determining glacial chronologies(1$sigma$<4%)through 10Be dating of moraines in the high Tropical Andes.Any inaccuracy attached to the scaling model is canceled out when the calibration site is located close to the dated object.The same experiment was also undertaken in pyroxene and plagioclase from two andesitic boulders from the Tunupavolcano moraines,exposed at 3800m and 4200m.A3He--10Be production ratio of 35.9textpm1.3(1$sigma$)is obtained for this mineral pair,indicating that the 10Be production rate in plagioclase is about 8%lower than in quartz. |
Blard, P. H., Lavé, J., Sylvestre, F., Placzek, C. J., Claude, C., Galy, V., Condom, T., Tibari, B. Cosmogenic 3He production rate in the high tropical Andes (3800m,20◦S): Implications for the local last glacial maximum (Article de journal) Dans: Earth and Planetary Science Letters, vol. 377-378, p. 260–275, 2013. @article{Blard_etal2013_2,
title = {Cosmogenic 3He production rate in the high tropical Andes (3800m,20◦S): Implications for the local last glacial maximum},
author = {P. H. Blard and J. Lav\'{e} and F. Sylvestre and C. J. Placzek and C. Claude and V. Galy and T. Condom and B. Tibari},
doi = {10.1016/j.epsl.2013.07.006},
year = {2013},
date = {2013-01-01},
journal = {Earth and Planetary Science Letters},
volume = {377-378},
pages = {260--275},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Garçon, M., Chauvel, C., France-Lanord, C., Huyghe, P., Lavé, J. Continental sedimentary processes decouple Nd and Hf isotopes (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 121, p. 177–195, 2013. @article{Garon_etal2013,
title = {Continental sedimentary processes decouple Nd and Hf isotopes},
author = {M. Gar\c{c}on and C. Chauvel and C. France-Lanord and P. Huyghe and J. Lav\'{e}},
doi = {10.1016/j.gca.2013.07.027},
year = {2013},
date = {2013-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {121},
pages = {177--195},
abstract = {The neodymium and hafnium isotopic compositions of most crustal and mantle rocks correlate to form the textquotelefttextquoteleftTerrestrial Arraytextquoterighttextquoteright. However, it is now well established that whereas coarse detrital sediments follow this trend, fine-grained oceanic sediments have high Hf ratios relative to their Nd isotopic ratios. It remains uncertain whether this textquotelefttextquoteleftdecouplingtextquoterighttextquoteright of the two isotopic systems only occurs in the oceanic environment or if it is induced by sedimentary processes in continental settings. In this study, the hafnium and neodymium isotopic compositions of sediments in large rivers is expressly used to constrain the behaviorof the two isotopic systems during erosion and sediment transport from continent to ocean. We report major and trace element concentrations together with Nd and Hf isotopic compositions of bedloads, suspended loads and river banks from the Ganges River and its tributaries draining the Himalayan Range i.e. the Karnali, the Narayani, the Kosi and the Marsyandi Rivers. The sample set includes sediments sampled within the Himalayan Range in Nepal, at the Himalayan mountain front, and also downstream on the floodplain and at the outflow of the Ganges in Bangladesh. Results show that hydrodynamic sorting of minerals explains the entire Hf isotopic range, i.e. more than 10eHf units, observed in the river sediments but does not affect the Nd isotopic composition. Bedloads and bank sediments have systematically lower eHf values than suspended loads sampled at the same location. Coarse-grained sediments lie below or on the Terrestrial Array in an eHf vs. eNd diagram. In contrast, fine-grained sediments, including most of the suspended loads, deviate from the Terrestrial Array toward higher eHf relative to their eNd, as is the case for oceanic terrigenous clays. The observed Nd--Hf decoupling is explained by mineralogical sorting processes that enrich bottom sediments in coarse and dense minerals, including unradiogenic zircons, while surface sediments are enriched in fine material with radiogenic Hf signatures. The data also show that Nd--Hf isotopic decoupling increases with sediment transport in the floodplain to reach its maximum at the river mouth. This implies that the Nd--Hf isotopic decoupling observed in worldwide oceanic clays and river sediments is likely to have the same origin. Finally, we estimated the Nd--Hf isotopic composition of the present-day mantle if oceanic sediments had never been subducted and conclude that the addition of oceanic sediments with their anomalous Nd--Hf isotopic compositions has slowly shifted the composition of the Earthtextquoterights mantle towards more radiogenic Hf values through time},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The neodymium and hafnium isotopic compositions of most crustal and mantle rocks correlate to form the textquotelefttextquoteleftTerrestrial Arraytextquoterighttextquoteright. However, it is now well established that whereas coarse detrital sediments follow this trend, fine-grained oceanic sediments have high Hf ratios relative to their Nd isotopic ratios. It remains uncertain whether this textquotelefttextquoteleftdecouplingtextquoterighttextquoteright of the two isotopic systems only occurs in the oceanic environment or if it is induced by sedimentary processes in continental settings. In this study, the hafnium and neodymium isotopic compositions of sediments in large rivers is expressly used to constrain the behaviorof the two isotopic systems during erosion and sediment transport from continent to ocean. We report major and trace element concentrations together with Nd and Hf isotopic compositions of bedloads, suspended loads and river banks from the Ganges River and its tributaries draining the Himalayan Range i.e. the Karnali, the Narayani, the Kosi and the Marsyandi Rivers. The sample set includes sediments sampled within the Himalayan Range in Nepal, at the Himalayan mountain front, and also downstream on the floodplain and at the outflow of the Ganges in Bangladesh. Results show that hydrodynamic sorting of minerals explains the entire Hf isotopic range, i.e. more than 10eHf units, observed in the river sediments but does not affect the Nd isotopic composition. Bedloads and bank sediments have systematically lower eHf values than suspended loads sampled at the same location. Coarse-grained sediments lie below or on the Terrestrial Array in an eHf vs. eNd diagram. In contrast, fine-grained sediments, including most of the suspended loads, deviate from the Terrestrial Array toward higher eHf relative to their eNd, as is the case for oceanic terrigenous clays. The observed Nd--Hf decoupling is explained by mineralogical sorting processes that enrich bottom sediments in coarse and dense minerals, including unradiogenic zircons, while surface sediments are enriched in fine material with radiogenic Hf signatures. The data also show that Nd--Hf isotopic decoupling increases with sediment transport in the floodplain to reach its maximum at the river mouth. This implies that the Nd--Hf isotopic decoupling observed in worldwide oceanic clays and river sediments is likely to have the same origin. Finally, we estimated the Nd--Hf isotopic composition of the present-day mantle if oceanic sediments had never been subducted and conclude that the addition of oceanic sediments with their anomalous Nd--Hf isotopic compositions has slowly shifted the composition of the Earthtextquoterights mantle towards more radiogenic Hf values through time |
Lupker, M., France-Lanord, C., Galy, V., Lavé, J., Kudrass, H. Increasing chemical weathering in the Himalayan system since the Last Glacial Maximum (Article de journal) Dans: Earth and Planetary Science Letters, vol. 365, p. 243–252, 2013. @article{Lupker_etal2013,
title = {Increasing chemical weathering in the Himalayan system since the Last Glacial Maximum},
author = {M. Lupker and C. France-Lanord and V. Galy and J. Lav\'{e} and H. Kudrass},
doi = {10.1016/j.epsl.2013.01.038},
year = {2013},
date = {2013-01-01},
journal = {Earth and Planetary Science Letters},
volume = {365},
pages = {243--252},
abstract = {Continental chemical weathering is central in Earthtextquoterights surface biogeochemical cycles as it redistributes elements across reservoirs such as the crust and the oceans.However the evolution of weathering through time and its response to external forcing such as changes in climate remain poorlyconstrained.In this work, a composite sediment record from the Bay of Bengal isused to document the evolution of chemical weathering in the Himalayan system(Himalayan range and Indo-Gangeticfloodplain),the world largest sediment convey or to the oceans,since the Last Glacial Maximum(LGM).The degree of weathering of the sediments isdocumented using mobile to immobile ratios such as K/SiandH2Oþ/Si as well as detrital calcite abundance. Robust weathering proxies are derived by correcting the chemical composition of sediment for sorting effects that occur during transport and deposition.The Bay of Bengal record is also further compared to the chemical composition of modern river sediments from the Ganga and Brahmaputra basin.Weathering proxies all indicate that the sediments exported by the Ganga and Brahmaputra Rivers became increasing lyweathered over the past 21 kyr,whereas,Sr,Nd and major elements suggest a constant sediment provenance in thesystem over the last 21kyr.These changes in the degree of weather in gof the sediments show that the weathering flux exported by the system to the Indian Ocean during the LGM was significant ly lower than at present and demonstrate that chemical weathering in continental scale basins such as the Ganga andBrahmaputra responds to Late Quaternary climate changes},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Continental chemical weathering is central in Earthtextquoterights surface biogeochemical cycles as it redistributes elements across reservoirs such as the crust and the oceans.However the evolution of weathering through time and its response to external forcing such as changes in climate remain poorlyconstrained.In this work, a composite sediment record from the Bay of Bengal isused to document the evolution of chemical weathering in the Himalayan system(Himalayan range and Indo-Gangeticfloodplain),the world largest sediment convey or to the oceans,since the Last Glacial Maximum(LGM).The degree of weathering of the sediments isdocumented using mobile to immobile ratios such as K/SiandH2Oþ/Si as well as detrital calcite abundance. Robust weathering proxies are derived by correcting the chemical composition of sediment for sorting effects that occur during transport and deposition.The Bay of Bengal record is also further compared to the chemical composition of modern river sediments from the Ganga and Brahmaputra basin.Weathering proxies all indicate that the sediments exported by the Ganga and Brahmaputra Rivers became increasing lyweathered over the past 21 kyr,whereas,Sr,Nd and major elements suggest a constant sediment provenance in thesystem over the last 21kyr.These changes in the degree of weather in gof the sediments show that the weathering flux exported by the system to the Indian Ocean during the LGM was significant ly lower than at present and demonstrate that chemical weathering in continental scale basins such as the Ganga andBrahmaputra responds to Late Quaternary climate changes |
Wilson, A., Lavé, J. The legacity of impact conditions in morphometrics of percussion marks on fluvial bedrock surfaces (Article de journal) Dans: Geomorphology, vol. 186, p. 174–180, 2013. @article{Wilson+Lav2013,
title = {The legacity of impact conditions in morphometrics of percussion marks on fluvial bedrock surfaces},
author = {A. Wilson and J. Lav\'{e}},
year = {2013},
date = {2013-01-01},
journal = {Geomorphology},
volume = {186},
pages = {174--180},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2012
|
Lavé, J., Lague, D. Ltextquoterightincision fluviale des orog`enes actifs (Article de journal) Dans: Geochronique, no. 124, p. 30–32, 2012. @article{Lav+Lague2012,
title = {Ltextquoterightincision fluviale des orog`enes actifs},
author = {J. Lav\'{e} and D. Lague},
year = {2012},
date = {2012-01-01},
journal = {Geochronique},
number = {124},
pages = {30--32},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Lupker, M., Blard, P. H., Lavé, J., France-Lanord, C., Leanni, L., Puchol, N., Charreau, J., Bourl`es, D. 10Be-derived Himalayan denudation rates and sediment budgets in the Ganga basin (Article de journal) Dans: Earth and Planetary Science Letters, vol. 333-334, p. 146–156, 2012. @article{Lupker_etal2012,
title = {10Be-derived Himalayan denudation rates and sediment budgets in the Ganga basin},
author = {M. Lupker and P. H. Blard and J. Lav\'{e} and C. France-Lanord and L. Leanni and N. Puchol and J. Charreau and D. Bourl`es},
doi = {10.1016/j.epsl.2012.04.020},
year = {2012},
date = {2012-01-01},
journal = {Earth and Planetary Science Letters},
volume = {333-334},
pages = {146--156},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Lupker, M., France-Lanord, C., Galy, V., Lavé, J., Gaillardet, J., Gajurel, A. P., Guilmette, C., Rahman, M., Singh, S. K., Sinha, R. Predominant floodplain over mountain weathering of Himalayan sediments (Ganga basin) (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 84, p. 410–432, 2012. @article{Lupker_etal2012_2,
title = {Predominant floodplain over mountain weathering of Himalayan sediments (Ganga basin)},
author = {M. Lupker and C. France-Lanord and V. Galy and J. Lav\'{e} and J. Gaillardet and A. P. Gajurel and C. Guilmette and M. Rahman and S. K. Singh and R. Sinha},
doi = {10.1016/j.gca.2012.02.001},
year = {2012},
date = {2012-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {84},
pages = {410--432},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2011
|
Blard, P. H., Sylvestre, F., Tripati, A. K., Claude, C., Causse, C., Coudrain, A., Condom, T., Seidel, J. L., Vimeux, F., Moreau, C., Dumoulin, J. P., Lavé, J. Lake highstands on the Altiplano (Tropical Andes) contemporaneous with Heinrich 1 and the Younger Dryas: new insights from 14C, UeTh dating and d18O of carbonates (Article de journal) Dans: Quaternary Science Reviews, vol. 30, p. 3973–3989, 2011. @article{Blard_etal2011,
title = {Lake highstands on the Altiplano (Tropical Andes) contemporaneous with Heinrich 1 and the Younger Dryas: new insights from 14C, UeTh dating and d18O of carbonates},
author = {P. H. Blard and F. Sylvestre and A. K. Tripati and C. Claude and C. Causse and A. Coudrain and T. Condom and J. L. Seidel and F. Vimeux and C. Moreau and J. P. Dumoulin and J. Lav\'{e}},
doi = {10.1016/j.quascirev.2011.11.001},
year = {2011},
date = {2011-01-01},
journal = {Quaternary Science Reviews},
volume = {30},
pages = {3973--3989},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Bouteiller, C. Le, Naaim-Bouvet, F., Mathys, N., Lavé, J. A new framework for modeling sediment fining during transport with fragmentation and abrasion (Article de journal) Dans: Journal of Geophysical Research ?Ĭ Earth Surface, vol. 116, 2011. @article{LeBouteiller_etal2011,
title = {A new framework for modeling sediment fining during transport with fragmentation and abrasion},
author = {C. Le Bouteiller and F. Naaim-Bouvet and N. Mathys and J. Lav\'{e}},
doi = {10.1029/2010JF001926},
year = {2011},
date = {2011-01-01},
journal = {Journal of Geophysical Research ?\u{I} Earth Surface},
volume = {116},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Lupker, M., France-Lanord, C., Lavé, J., Bouchez, J., Galy, V., Métivier, F., Gaillardet, J., Lartiges, B., Mugnier, J. L. A Rouse‐based method to integrate the chemical composition of river sediments: Application to the Ganga basin (Article de journal) Dans: Journal of Geophysical Research, vol. 116, no. F04012, 2011. @article{Lupker_etal2011,
title = {A Rouse‐based method to integrate the chemical composition of river sediments: Application to the Ganga basin},
author = {M. Lupker and C. France-Lanord and J. Lav\'{e} and J. Bouchez and V. Galy and F. M\'{e}tivier and J. Gaillardet and B. Lartiges and J. L. Mugnier},
doi = {10.1029/2010JF001947},
year = {2011},
date = {2011-01-01},
journal = {Journal of Geophysical Research},
volume = {116},
number = {F04012},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Steer, P., Rodolphe, C., Lavé, J., Godard, V. Surface Lagrangian Remeshing: A new tool for study long term evolution of continental lithosphere from 2D numerical modelling (Article de journal) Dans: Computers & Geosciences, vol. 37, no. 8, p. 1067–1074, 2011. @article{Steer_etal2011,
title = {Surface Lagrangian Remeshing: A new tool for study long term evolution of continental lithosphere from 2D numerical modelling},
author = {P. Steer and C. Rodolphe and J. Lav\'{e} and V. Godard},
doi = {10.1016/j.cageo.2010.05.023},
year = {2011},
date = {2011-01-01},
journal = {Computers \& Geosciences},
volume = {37},
number = {8},
pages = {1067--1074},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2010
|
Hatzfeld, D., Authemayou, C., der Beek, P. Van, Bellier, O., Lavé, J., Oveisi, B., Tatar, M., Tavakoli, F., Yamini-Fard, F., Walpersdorf, A. The kinematics of the Zagros Mountains (Iran) during the Meso-Cenozoic (Article de journal) Dans: Geological Society of London Special Publication, vol. 330, p. 19–42, 2010. @article{Hatzfeld_etal2010,
title = {The kinematics of the Zagros Mountains (Iran) during the Meso-Cenozoic},
author = {D. Hatzfeld and C. Authemayou and P. Van der Beek and O. Bellier and J. Lav\'{e} and B. Oveisi and M. Tatar and F. Tavakoli and F. Yamini-Fard and A. Walpersdorf},
doi = {10.1144/SP3303.3},
year = {2010},
date = {2010-01-01},
journal = {Geological Society of London Special Publication},
volume = {330},
pages = {19--42},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2009
|
Attal, M., Lavé, J. Pebble abrasion during fluvial transport: Experimental results and implications for the evolution of the sediment load along rivers (Article de journal) Dans: Journal of Geophysical Research, vol. 114, no. FO-4023, p. 1–22, 2009. @article{Attal+Lav2009,
title = {Pebble abrasion during fluvial transport: Experimental results and implications for the evolution of the sediment load along rivers},
author = {M. Attal and J. Lav\'{e}},
doi = {10.1029/2009JF001328},
year = {2009},
date = {2009-01-01},
journal = {Journal of Geophysical Research},
volume = {114},
number = {FO-4023},
pages = {1--22},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Blard, P. H., Lavé, J., Farley, K. A., Fornari, M., Jimenez, N., Ramirez, V. Late local glacial maximum in the Central Altiplano triggered by cold and locally-wet conditions during the paleolake Tauca episode (17--15 ka, Heinrich 1) (Article de journal) Dans: Quaternary Science Reviews, vol. 28, p. 3414–3427, 2009. @article{Blard_etal2009,
title = {Late local glacial maximum in the Central Altiplano triggered by cold and locally-wet conditions during the paleolake Tauca episode (17--15 ka, Heinrich 1)},
author = {P. H. Blard and J. Lav\'{e} and K. A. Farley and M. Fornari and N. Jimenez and V. Ramirez},
doi = {10.1016/j.quascirev.2009.09.025},
year = {2009},
date = {2009-01-01},
journal = {Quaternary Science Reviews},
volume = {28},
pages = {3414--3427},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Godard, V., Cattin, R., Lavé, J. Erosional control on the dynamics of low-convergence rate continental plateau margins (Article de journal) Dans: Geophysical Journal International, vol. 179, p. 763–777, 2009. @article{Godard_etal2009,
title = {Erosional control on the dynamics of low-convergence rate continental plateau margins},
author = {V. Godard and R. Cattin and J. Lav\'{e}},
doi = {10.1111/j.1365-246X.2009.04324.x},
year = {2009},
date = {2009-01-01},
journal = {Geophysical Journal International},
volume = {179},
pages = {763--777},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Godard, V., Pik, R., Lavé, J., Cattin, R., Tibari, B., Sigoyer, J., Pubellier, M., Zhu, J. Late Cenozoic evolution of the central Longmen Shan, eastern Tibet: Insight from (U-Th)/He thermochronometry (Article de journal) Dans: Tectonics, vol. 28, no. TC5009, p. 1–17, 2009. @article{Godard_etal2009_2,
title = {Late Cenozoic evolution of the central Longmen Shan, eastern Tibet: Insight from (U-Th)/He thermochronometry},
author = {V. Godard and R. Pik and J. Lav\'{e} and R. Cattin and B. Tibari and J. Sigoyer and M. Pubellier and J. Zhu},
doi = {10.1029/2008TC002407},
year = {2009},
date = {2009-01-01},
journal = {Tectonics},
volume = {28},
number = {TC5009},
pages = {1--17},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Oveisi, B., Lavé, J., der Beek, P. Van, Carcaillet, J., Benedetti, L., Braucher, R., Aubourg, C. Thick- and thin-skinned deformation rates in the Zagros SImple Folded Zone (Iran) indicated by displacement of geomorphic surfaces (Article de journal) Dans: Geophysical Journal International, vol. 176, p. 627–654, 2009. @article{Oveisi_etal2009,
title = {Thick- and thin-skinned deformation rates in the Zagros SImple Folded Zone (Iran) indicated by displacement of geomorphic surfaces},
author = {B. Oveisi and J. Lav\'{e} and P. Van der Beek and J. Carcaillet and L. Benedetti and R. Braucher and C. Aubourg},
year = {2009},
date = {2009-01-01},
journal = {Geophysical Journal International},
volume = {176},
pages = {627--654},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2007
|
Blard, P. H., Lavé, J., Pik, R., Wagnon, P., Bourl`es, D. Persistence of full glacial conditions in the central Pacific until 15,000 years ago (Article de journal) Dans: Nature, vol. 449, no. 7162, p. 585–591, 2007. @article{Blard_etal2007,
title = {Persistence of full glacial conditions in the central Pacific until 15,000 years ago},
author = {P. H. Blard and J. Lav\'{e} and R. Pik and P. Wagnon and D. Bourl`es},
doi = {10.1038/nature06142},
year = {2007},
date = {2007-01-01},
journal = {Nature},
volume = {449},
number = {7162},
pages = {585--591},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Garzanti, E., Vezzoli, G., Ando, S., Lavé, J., Attal, M., France-Lanord, C., DeCelles, P. Quantifying sand provenance and erosion (Marsyandi River, Nepal Himalaya) (Article de journal) Dans: Earth and Planetary Science Letters, vol. 258, p. 500–515, 2007. @article{Garzanti_etal2007,
title = {Quantifying sand provenance and erosion (Marsyandi River, Nepal Himalaya)},
author = {E. Garzanti and G. Vezzoli and S. Ando and J. Lav\'{e} and M. Attal and C. France-Lanord and P. DeCelles},
year = {2007},
date = {2007-01-01},
journal = {Earth and Planetary Science Letters},
volume = {258},
pages = {500--515},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
