Publications CRPG

@article{Bekaert_etal2023,

title = {Last glacial maximum cooling of 9 textdegreeC in continental Europe from a 40 kyr-long noble gas paleothermometry record},

author = {D. V. Bekaert and P. H. Blard and Y. Raoult and R. Pik and R. Kipfer and A. M. Seltzer and E. Legrain and B. Marty},

doi = {10.1016/j.quascirev.2023.108123},

year  = {2023},

date = {2023-01-01},

journal = {Quaternary Science Reviews},

volume = {310},

pages = {108123},

abstract = {The Last Glacial Maximum (LGM; \^{a}`u26--18 kyr ago) is a time interval of great climatic interest characterized by substantial global cooling driven by radiative forcings and feedbacks associated with orbital changes, lower atmospheric CO2, and large ice sheets. However, reliable proxies of continental paleotemperatures are scarce and often qualitative, which has limited our understanding of the spatial structure of past climate changes. Here, we present a quantitative noble gas temperature (NGT) record of the last \^{a}`u40 kyr from the Albian aquifer in Eastern Paris Basin (France, \^{a}`u48textdegreeN). Our NGT data indicate that the mean annual surface temperature was \^{a}`u5 textdegreeC during the Marine Isotope Stage 3 (MIS3; \^{a}`u40--30 kyr ago), before cooling to \^{a}`u2 textdegreeC during the LGM, and warming to \^{a}`u11 textdegreeC in the Holocene, which closely matches modern ground surface temperatures in Eastern France. Combined with water stable isotope analyses, NGT data indicate $delta$D/NGT and $delta$18O/NGT transfer functions of +1.6 textpm 0.4texttenthousand/textdegreeC and +0.18 textpm 0.04texttenthousand/textdegreeC, respectively. Our noble-gas derived LGM cooling of \^{a}`u9 textdegreeC (relative to the Holocene) is consistent with previous studies of noble gas paleothermometry in European groundwaters but larger than the low-to-mid latitude estimate of 5.8 textpm 0.6 textdegreeC derived from a compilation of noble gas records, which supports the notion that continental LGM cooling was more extreme at higher latitudes. While an LGM cooling of \^{a}`u9 textdegreeC in Eastern France appears compatible with recent data assimilation studies, this value is greater than most estimates from current-generation climate model simulations of the LGM. Comparing our estimate for the temperature in Eastern France during MIS3 (6.4 textpm 0.5 textdegreeC) with GCM outputs presents a promising avenue to further evaluate climate model simulations and constrain European climate evolution over the last glacial cycle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Blard_etal2023,

title = {Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations},

author = {P. H. Blard and M. Protin and J. L. Tison and F. Fripiat and D. Dahl-Jensen and J. P. Steffensen and W. C. Mahaney and P. R. Bierman and A. J. Christ and L. B. Corbett and V. Debaille and T. Rigaudier and P. Claeys and ASTER Team.},

doi = {10.1017/jog.2022.122},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Glaciology},

volume = {614},

pages = {1--19},

abstract = {We present new data from the debris-rich basal ice layers of the NEEM ice core (NW Greenland). Using mineralogical observations, SEM imagery, geochemical data from silicates (meteoric 10Be, $epsilon$Nd, 87Sr/86Sr) and organic material (C/N, $delta$13C), we characterize the source material, succession of previous glaciations and deglaciations and the paleoecological conditions during ice-free episodes. Meteoric 10Be data and grain features indicate that the ice sheet interacted with paleosols and eroded fresh bedrock, leading to mixing in these debris-rich ice layers. Our analysis also identifies four successive stages in NW Greenland: (1) initial preglacial conditions, (2) glacial advance 1, (3) glacial retreat and interglacial conditions and (4) glacial advance 2 (current ice-sheet development). C/N and $delta$13C data suggest that deglacial environments favored the development of tundra and taiga ecosystems. These two successive glacial fluctuations observed at NEEM are consistent with those identified from the Camp Century core basal sediments over the last 3 Ma. Further inland, GRIP and GISP2 summit sites have remained glaciated more continuously than the western margin, with less intense ice-substratum interactions than those observed at NEEM.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Laurent_etal2023,

title = {Timescales of ultra-high temperature metamorphism and crustal differentiation: Zircon petrochronology from granulite xenoliths of the Variscan French Massif Central},

author = {O. Laurent and S. Couzini\'{e} and L. S. Doucet},

doi = {10.1016/j.epsl.2023.118133},

year  = {2023},

date = {2023-01-01},

journal = {Earth and Planetary Science Letters},

volume = {611},

pages = {118133},

abstract = {Lower crustal ultra-high temperature (UHT) metamorphism and the resulting production and transfer of granitic magmas represent key processes of intracrustal differentiation. The timescales of these phenomena are debated, due to the complexity of the granulite zircon U-Pb record and because direct links between granulites and granites are difficult to establish. To address these issues, we present the results of zircon petrochronology (coupled U-Pb dating, trace element and Lu-Hf isotopic analyses) for lower crustal felsic and mafic granulite xenoliths from the Variscan eastern French Massif Central and compare them with data from well-characterized mid-/upper crustal migmatites and granites. The felsic and mafic granulites represent pre-Variscan meta-sedimentary and meta-igneous mafic rocks, respectively; which experienced Variscan UHT peak metamorphism at 940--970\^{a}—¦C and 8 textpm2 kbar. Zircons from the felsic granulites show U-Pb dates spreading over \^{a}`u50 Myr between \^{a}`u315 and \^{a}`u265 Ma, correlated to Ti-in-zircon temperatures decreasing from 940--970\^{a}—¦C to 800\^{a}—¦C and REE contents consistent with growth in equilibrium with garnet at (U)HT conditions. This is best explained by continuous crystallization of zircon upon cooling from the thermal peak owing to decreasing Zr solubility of residual melt, despite significant prograde melt loss. Zircons from the mafic granulite only record the last stage of this time-temperature evolution (295--265 Ma; 800--900\^{a}—¦C) due to later zircon saturation. Upper crustal granite emplacement started at 340 Ma and culminated at the age of the lower crustal thermal peak of 313 textpm3 Ma (defined by the highest-temperature zircons from felsic granulites), reflecting melt extraction along the \^{a}`u27 Myr prograde path of the lower crust. In turn, the crystallization ages of mid-crustal migmatites (315--300 Ma) and the lower crustal granulites (315--265 Ma) are consistent with slow cooling in the presence of melt. These results provide a direct assessment of the timescales of melt production and residence at the crustal scale; and validate the granulite-granite connection in the framework of the melt loss theory in migmatitic systems},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Piani_etal2023,

title = {Hydrogen isotopic composition of hydrous minerals in Asteroid Ryugu},

author = {L. Piani and K. Nagashima and N. Kawasaki and N. Sakamoto and K. I. Bajo and Y. Abe and J. and Al\'{e}on},

doi = {10.3847/2041-8213/acc393},

year  = {2023},

date = {2023-01-01},

journal = {The Astrophysical Journal},

volume = {946},

number = {L43},

abstract = {Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu’s hydrous minerals, D/HRyugu, to be [165 textpm 19] texttimes 10\^{a}ˆ’6, which corresponds to $delta$DRyugu = +59 textpm 121texttenthousand (2$sigma$). The hydrous mineral D/HRyugu’s values for the two sampling sites on Ryugu are similar; they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a linkbetween Ryugu and CI chondrites and an inference that Ryugu’s samples, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth’s surficial reservoirs is evaluated to be \^{a}`u3%. We conclude that the water responsible for the alteration of Ryugu’s rocks was derived from water ice precursors inherited from the interstellar medium; the ice partially reequilibrated its hydrogen with the nebular H2 before being accreted on the Ryugu’s parent asteroid.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Caurant_etal2023,

title = {Redox heterogeneities in a subducting slab: Example from the Monviso meta-ophiolite (Western Alps, Italy)},

author = {C. Caurant and B. Debret and B. M\'{e}nez and C. Nicollet and P. Bouilhol},

doi = {10.1016/j.lithos.2023.107136},

year  = {2023},

date = {2023-01-01},

journal = {Lithos},

volume = {446-447},

pages = {107136},

abstract = {Variations of redox conditions (i.e., oxygen fugacity, fO2) accompanying slab dehydration in subduction zones are subject to ongoing controversies, especially since the interplay between redox sensitive elements during prograde metamorphism remains complex and, likely, variable at the slab scale. Here we investigate fO2 variations during serpentinite dehydration and their feedback on the stability of sulfur and carbon compounds by studying the eclogitic Monviso meta-ophiolite (Western Alps, Italy). Despite a complex metamorphic history, the Monviso massif has preserved a complete section of oceanic lithosphere, from seafloor metasediments, meta-ophicarbonates and metabasites to deep-seated metagabbros and metaserpentinites. By bringing new estimates in the northern massif, we show that these lithologies have recorded a homogeneous pressure and temperature (P-T) climax, at 520--570 textdegreeC and 2.6--2.7 GPa, on the whole meta-ophiolite. Despite this homogeneous P-T record, serpentinite forming minerals imply strong variations in fO2 according to their position in the slab, from high fO2 conditions (textasciitilde FMQ +2) in the deep-seated lithologies made of heazlewoodite-magnetite-olivine assemblages to low fO2 (textasciitilde FMQ −4) in the paleoseafloor lithologies made of pentlandite-awaruite-olivine. This redox gradient is opposed to what is expected at mid-ocean ridges and is therefore likely set up during serpentinite dehydration. Such variations of fO2 conditions also influenced carbon distribution and redox state within the lithosphere. In particular, reducing conditions associated with brucite breakdown in paleoseafloor serpentinites promote the formation of disordered carbonaceous matter over inorganic carbonates. Newly-formed disordered carbonaceous matter could subsequently be recycled in the deep mantle, with the potential to play a major role on the deep carbon cycle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Boulanger+France2023,

title = {Cumulate formation and melt extraction from mush-dominated magma reservoirs: The melt flush process exemplified at mid-ocean ridges},

author = {M. Boulanger and L. France},

doi = {ht10.1093/petrology/egad005},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Petrology},

volume = {64},

number = {2},

pages = {1--20},

abstract = {Volcanism is the surface expression of extensive magmatic systems, with their intrusive counterpart representing textasciitilde80% of the total magma budget. Our knowledge of igneous processes therefore largely relies on our understanding of deep plutonic processes. In continental or oceanic environments, most of the intrusive igneous rocks bear geochemical cumulate signatures (e.g. depletion in incompatible elements and enrichment in compatible ones) that are commonly explained by mineral-melt segregation during differentiation. Deformation-assisted compaction aided by melt buoyancy is usually referred to as the main process involved in melt extraction. However, buoyancy alone is not sufficient, and a number of cumulative rocks are lacking any compaction evidence, opening the potential for the involvement of other processes. In addition, our view of magmatic systems has shifted in the last decades from large melt-rich bodies to crystal-rich magma reservoirs. This paradigm shift challenges some of the long-established first-order igneous concepts like the idea that melt differentiation at depth is mainly governed by (fractional) crystallization; alternatively, the presence of mush potentially favors additional processes such as melt-mush reactions. We propose a novel igneous process for the formation of igneous cumulates, consistent with the mushy nature of oceanic igneous reservoirs, their continuous/cyclic replenishment by primitive melts, and the widespread occurrence of reactive porous flow (RPF) during magma differentiation identified in a growing number of magmatic systems. The melt flush process relies on melt-mush reactions between the primitive recharge melt(s) and crystal mush. Replacement of the more evolved interstitial melt by the primitive recharge melt leading to reactions (dissolution+crystallization) and concomitant extraction of the more evolved melt from the cumulate by buoyancy participate in the acquisition of the final cumulate signature. This process relying on oceanic igneous systems considers for the first time melt inputs and not only melt extraction and matches the petrographic (e.g. mineral dissolution evidence) and geochemical constraints (trace element signatures) brought by natural oceanic samples. We tested various melt-mush reactions likely involved in the early stages of the melt flush process during RPF to investigate their thermodynamic feasibility with the Magma Chamber Simulator. First-order results show that one-step equilibration of primitive melts with primitive to moderately differentiated mush crystals triggers mineral assimilation. Together with the constraints established from the natural rock record, it strengthens the idea that RPF is a potential key process for magma differentiation in magma reservoirs at different evolution stages. The proposed melt flush process eventually adds to other processes involved in cumulate formation like magma compaction or crystal settling and is likely to apply to any other magmatic system from various settings sharing similar reservoir characteristics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@article{Seltzer_etal2023,

title = {Terrestrial amplification of past, present, and future climate change},

author = {A. M. Seltzer and P. H. Blard and S. C. Sherwood and M. Kageyama},

doi = {10.1126/sciadv.adf8119},

year  = {2023},

date = {2023-01-01},

journal = {Science Advances},

volume = {9},

number = {9},

pages = {eadf8119},

abstract = {Terrestrial amplification (TA) of land warming relative to oceans is apparent in recent climatic observations. TA results from land-sea coupling of moisture and heat and is therefore important for predicting future warming and water availability. However, the theoretical basis for TA has never been tested outside the short instrumental period, and the spatial pattern and amplitude of TA remain uncertain. Here, we investigate TA during the Last Glacial Maximum (LGM; textasciitilde20 thousand years) in the low latitudes, where the theory is most applicable. We find remarkable consistency between paleotemperature proxies, theory, and climate model simulations of both LGM and future climates. Paleoclimate data thus provide crucial new support for TA, refining the range of future lowlatitude, low-elevation TA to 1:37 +0:27 ?\u{I} 0:23 (95% confidence interval), i.e., land warming textasciitilde40% more than oceans. The observed data model theory agreement helps reconcile LGM marine and terrestrial paleotemperature proxies, with implications for equilibrium climate sensitivity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Tachambalath_etal2023,

title = {Data report: major and trace element composition of silicates and carbonates from Bengal Fan sediments, IODP Expedition 354},

author = {A. P. Tachambalath and C. France-Lanord and A. Galy and T. Rigaudier and J. Charreau},

doi = {10.14379/iodp.proc.354.204.2023},

year  = {2023},

date = {2023-01-01},

journal = {Proceedings of the International Ocean Discovery Program},

volume = {354},

abstract = {During International Ocean Discovery Program Expedition 354, seven sites were drilled along a 320 km east--west transect at 8textdegreeN, constituting a relic of the Neogene sediment record of Himalayan erosion. Bengal Fan is one of the largest deep-sea fans in the world where turbiditic sediments issued from the Ganga and Brahmaputra River Delta and originally supplied by the Himalayan erosion of silicate and carbonate lithologies are deposited and stored. Quantification ofthe chemical composition of silicates and carbonates is necessary to understand the tectonoclimatic history of this region. This report presents the major and trace element concentrations of silicate and carbonate fractions of selected turbiditic samples from Sites U1450 and U1451. Efficient washing followed by refined acid leaching of the sediments was performed to eliminate sea salts and carbonates from these marine sediment samples. Shipboard samples show 20%--40% excess sodium concentration associated with sea salt derived from pore water. Weak acid treatment limits the total carbonate content in the samples to less than 0.1%. Depletion of major and trace elements observed due to acid leaching is attributed to the dissolution of carbonates and cations associated with Fe-Mn oxyhydroxides.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{LeRoux_etal2023,

title = {Lead from Notre-Dame fire plume caught 15 km from Paris},

author = {G. Le Roux and O. Masson and C. Cloquet and M. J. Tavella and M. Beguin-Leprieur and O. Saunier and D. Baqu\'{e} and T. Camboulive and J. Berger and T. Aigouy and F. Maube and S. Baron and S. Ayrault and M. L’H\'{e}ritier},

doi = {10.1021/acsearthspacechem.2c00321},

year  = {2023},

date = {2023-01-01},

journal = {ACS Earth and Space Chemistry},

volume = {7},

pages = {310--314},

abstract = {Thanks to the use of filters collected daily in the west of Paris, we confirm the passage of the lead-laden plume following the fire on the roof and spire of Notre-Dame Cathedral in April 2019. The measured concentrations on the filter (Pb = 1.4 $mu$g m−3), scanning electron microscopy and Hysplit simulation, correspond to an estimate of a few hundred kilograms of lead that would have been volatilized and then oxidized in the form of micronic and submicronic aerosols. The concentrations found in the plume are, however, much lower than those found in the environment in the 1980s and 1990s but are 100 times higher than those found in times prior to and after the fire. The isotopic signature of the plume is almost identical to that of the fine Pb dust found inside the Notre-Dame building. It is different from the isotopic signature of the Parisian atmosphere before and after the fire, but it is similar to that of the atmospheric Pb legacy recorded by peat cores over the last 300 years in France. The presence of very fine lead-bearing particles makes them potentially transportable over long distances after large urban fires. Our study shows the value of daily aerosol sampling to retrospectively trace the plumes of air pollutants from industrial accidents but also from historical monument fires such as Notre-Dame in 2019.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Marrocchi_etal2023,

title = {Hydrogen isotopic evidence for nebular pre-hydration and the limited role of parent-body processes in CM chondrites},

author = {Y. Marrocchi and T. Rigaudier and M. Piralla and L. Piani},

doi = {10.1016/j.epsl.2023.118151},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {Earth and Planetary Science Letters},

volume = {611},

number = {2},

pages = {118151},

abstract = {The conditions and environments in which hydrated phases in unequilibrated meteorites formed remain debated. Among carbonaceous chondrites, Mighei-type chondrites (CMs) display a large range in the degree of aqueous alteration, and thus record different stages of hydration and alteration. Here, we report the bulk H, C, and N contents, H and C isotopic compositions, and thermogravimetric signatures of the most-and least-altered CMs known so far, Kolang and Asuka 12236, respectively. We also report in-situSIMS measurements of the hydrogen isotopic compositions of water in both chondrites. Compared to other CMs, Asuka 12236 has the lowest bulk water content (3.3 wt.% H2O) and the most D-rich water and bulk isotopic compositions ($delta$D =180 and 280 , respectively). Combined with literature data, our results show that phyllosilicate-bearing CMs altered to varying degrees accreted water-ice grains with similar isotopic compositions. These results demonstrate that the hydrogen isotopic variations in CM chondrites (i) are not controlled by secondary alteration processes and (ii) were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. The minimally altered CM chondrites Paris and Asuka 12236 display peculiar, D-rich, hydrogen isotopic compositions that imply the presence of another H-bearing component in addition to insoluble organic matter and phyllosilicates. This component is most likely the hydrated amorphous silicates that are ubiquitous in these chondrites. CM bulk H and O isotopic compositions are linearly correlated, implying that (i) amorphous silicates in CM matrices were already hydrated by disk processes before the onset of CM parent-body alteration, and (ii) the quest for a hypothetically water-free CM3 is illusory.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Flahaut_etal2023,

title = {New detections of feldspar-bearing volcanic rocks in the walls of Valles Marineris, Mars},

author = {J. Flahaut and V. Payet and F. Fueten and M. Guitreau and M. Barthez and G. Ito and P. Allemand},

doi = {10.1029/2022GL100772},

year  = {2023},

date = {2023-01-01},

journal = {Geophysical Research Letters},

volume = {50},

pages = {e2022GL100772},

abstract = {Plagioclase-bearing rocks were first detected in the vicinity of large impact basins on Mars using visible/near-infrared (VNIR) data. The geologic context is consistent with excavated plutons or ancient crustal outcrops. Our analyses reveal plagioclase outcrops exposed in a 200 m thick, sub-horizontal layer in the 8 km deep walls of the Valles Marineris canyon. These plagioclase-bearing rocks are consistent with either a sill, a volcano-clastic layer, or a porphyritic lava flow, in contrast with the previous understanding that plagioclase feldspar signatures must be indicative of nearly pure, anorthositic rocks inherited from a primary flotation crust or granitoids from either plutonic activity or ancient continental crust. We present here evidence of possibly effusive, volcanic rocks bearing plagioclase VNIR spectral signatures, expanding the geologic setting of these unique and uncommon martian rocks to include multiple lithologies. This has direct implications for Mars magmatic processes and for the nature of its crust.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Piralla_etal2023,

title = {A unified chronology of dust formation in the early solar system},

author = {M. Piralla and J. Villeneuve and N. Schnuriger and D. V. Bekaert and Y. Marrocchi},

doi = {10.1016/j.icarus.2023.115427},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {Icarus},

volume = {394},

pages = {115427},

abstract = {The chronology of dust formation in the early solar system remains controversial. Chondrules are the most abundant high-temperature objects formed during the evolution of the circumsolar disk. Considering chondrule formation, absolute lead‑lead (Pb--Pb) ages and aluminum‑magnesium (26Al--26Mg) ages relative to calcium‑aluminum-rich inclusions (CAIs) provide inconsistent chronologies, with Pb--Pb ages showing early and protracted chondrule formation episodes whereas 26Al--26Mg ages suggest that chondrule production was delayed by \>1.5 Ma. Here, we develop a new method to precisely determine in situ 26Al--26Mg ages of spinelbearing chondrules, which are not affected by secondary asteroidal processes. Our data demonstrate that 26Al--26Mg chondrule formation ages are actually 1 Ma older than previously thought and extend over the entire lifetime of the disk. This shift in chondrule formation ages relative to CAIs, however, is not sufficient to reconcilethe Pb--Pb and 26Al--26Mg chronologies of chondrule and achondrite formation. Thus, either chondrules’Pb--Pb ages and volcanic achondrites’ 26Al--26Mg ages are incorrect or the age of CAIs should be reevaluated at 4,568.7 Ma to ensure consistency between chronometers. We favor the second hypothesis, given that (i) thecanonical age of CAIs was determined using only 4 specimens and (ii) older ages of 4,568.2 Ma have also been measured. We show that the adoption of 4,568.7 Ma as the new canonical age of CAIs and the use of our new spinel-derived 26Al--26Mg ages enable reconciling the Pb--Pb and 26Al--26Mg ages of chondrules and achondrites.This new chronology implies the existence of a 0.7--1 Ma gap between the formation of refractory inclusions and chondrules, and supports the homogeneous distribution of 26Al in the circumsolar disk.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Thiry_etal2022,

title = {Albitization and oxidation of Variscan granitoid rocks related to the post-Variscan paleosurface in the Sudetes (Bohemian Massif, SW Poland)},

author = {M. Thiry and C. Franke and K. F. E. Yao and A. Szuszkiewicz and C. Fabrega and M. Jelenska and M. Kadzialko-Hofmokl and A. Gurenko and D. Parcerisa and A. Sobczyk and K. Turniak and P. Aleksandrowski},

doi = {10.1007/s00531-022-02274-2},

year  = {2022},

date = {2022-01-01},

journal = {International Journal of Earth Sciences},

abstract = {The reddened granitoid facies in the basement of the Polish Sudetes exhibits two categories of alteration spatially arranged with respect to fractures: (1) saussuritization and sericitization within light-colored facies in the interior of fracture-bounded blocks and (2) albitization and hematization in reddened facies occurring adjacent to fracture walls. These alterations are associated with the chloritization of primary ferromagnesian minerals and the development of secondary minerals such as quartz, K-feldspar, apatite, prehnite, calcite, and titanite. We link these parageneses and the observed zonation to a unique alteration event consisting of an interplay of chemical reactions of variable spatial extent. The complete albitization of the feldspars (plagioclase and K-feldspar) adjacent to fractures points to a significant supply of Na for albite neoformation and the availability of oxygen to form the associated hematite. The dating of the iron oxides by paleomagnetism and the secondary monazite associated with the albitized facies by U-Th-Pbtotal unambiguously indicates their post-Variscan ages. In this context, the alterations are related to a regionally widespread post-Variscan paleosurface. The weathering profiles formed in phreatic groundwater environments downgradient of highlands that provided a hydrological head. Sodium supply likely originated from gigantic salt playas that characterized Permian and Triassic lowlands. Weathering was interrupted by the Mesozoic transgression. The recognition of these weathering profiles over extensive parts of the Variscan Belt provides the basis for reconstructing the post-Variscan paleosurface and constraining Triassic and post-Triassic geodynamics, including erosion rates and geomorphological evolution of the Paleozoic massifs in Europe.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Rudraswami_etal2022,

title = {In-situ O-isotope analysis of relict spinel and forsterite in small (\<200 $mu$m) Antarctic micrometeorites -- Samples of chondrules \& CAIs from carbonaceous chondrites},

author = {N. G. Rudraswami and M. D. Suttle and Y. Marrocchi and S. Taylor and J. Villeneuve},

doi = {10.1016/j.gca.2022.03.015},

year  = {2022},

date = {2022-01-01},

journal = {Geochimica et Cosmochimica Acta},

volume = {325},

pages = {1--24},

abstract = {We report high-precision secondary ion mass spectrometer triple oxygen isotope systematics (95 individual analyses) from 37 micrometeorites (MMs) collected from South Pole Water Well (SPWW), Antarctica. The study population focuses on unmelted coarse-grained (Cg) MMs (n = 23) with both multiple (n = 14) and single-mineral (n = 9) varieties investigated. We also analysed relict minerals in porphyritic cosmic spherules (n = 13) and the relict matrix in a single scoriaceous fine-grained (Fg) MM. The target minerals investigated are primarily olivine (Fo \^{a}`u 43--99%) and spinel. Textural, chemical and isotopic data confirm that both olivine and spinel grains have retained their pre-atmospheric O-isotope compositions, allowing inferences to be drawn about their formation and parent body affinities. We separate the study population into three groups: spinel-free particles (consisting of the CgMMs and PO cosmic spherules), spinel-bearing MMs and the single FgMM.Olivine grains in spinel-free MMs vary between $delta$17O: \^{a}ˆ’12.6texttenthousand and +3.5texttenthousand, $delta$18O: \^{a}ˆ’9.6texttenthousand and +7.5texttenthousand, and $Delta$17O: \^{a}ˆ’9.5texttenthousand and +1.3texttenthousand and define a slope-1 profile in $delta$18O--$delta$17O isotope space. They are most likely fragmented chondrules, with both type I and type II varieties represented. Their observed Mg#-$Delta$17O distribution is best explained by a mixture of CM chondrules and either CR chondrules, Tagish Lake chondrules or WILD2 cometary silicates. One of these chondrule-like MMs has an isotopically heterogeneous composition, characterised by a single olivine grain with a markedly 16O-rich composition ($Delta$17O: \^{a}ˆ’16.3texttenthousand), suggesting it is a relict silicate fragment of AOA material that was incorporated into the chondrule precursor.We analysed 11 spinel grains in five spinel-bearing MMs. In all instances spinels are nearly pure MgAl2O4 with isotopically light (16O-rich) compositions (ranging from $delta$17O: \^{a}ˆ’34.4texttenthousand to \^{a}ˆ’0.9texttenthousand, $delta$18O: \^{a}ˆ’30.8texttenthousand to +11.0texttenthousand, and $Delta$17O: \^{a}ˆ’18.3texttenthousand to \^{a}ˆ’4.4texttenthousand). They are therefore 16O-poor relative to spinel found in unaltered CAIs, indicating a different origin. Grains with high Cr2O3 contents (\>0.5 wt.%) are interpreted originating from Al-rich chondrule precursors, while low Cr2O3 spinels (\<0.5 wt.%) are interpreted as CAI-derived material affected by parent body aqueous alteration.Finally, we report a single FgMM with a 16O-poor composition ($Delta$17O \> 0texttenthousand and $delta$18O \> +15.0texttenthousand). This particle adds to our growing inventory of water-rich C-type asteroid samples united by their formation history which is characterised by accretion of abundant heavy water.Our work strongly supports findings from earlier in-situ O-isotope studies, concluding that small MMs overwhelmingly sample material from CC parent bodies and that CgMMs largely sample chondrules and, to a lesser extent, CAI material. The analysis of CgMMs therefore provides insights into the primitive O-isotope reservoirs that were present in the early solar system and how they interacted.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Quesnel_etal2022,

title = {Significance of H2 and CO release during thermal treatment of natural phyllosilicate-rich rocks},

author = {B. Quesnel and L. Truche and M. Cathelineau and M. C. Boiron and M. Lempart-Drozd and T. Rigaudier and A. Derkowski and E. C. Gaucher},

doi = {10.1016/j.chemgeo.2021.120647},

year  = {2022},

date = {2022-01-01},

journal = {Chemical Geology},

volume = {588},

pages = {120647},

abstract = {Phyllosilicates may trap hydrogen (H2) in the crust, but they may also produce it through various processes, including oxidative dehydrogenation. The dehydrogenation temperature depends on the type and composition of the phyllosilicates considered, but it may be as low as 300 textdegreeC. Here, we document the release of H2 and CO during thermal treatment of chloritite (300 textdegreeC) and talc (500 textdegreeC) from the Trimouns deposits (Eastern Pyrenees, France). Thermal release of gases coupled to stable isotope analysis has been used to recover and characterize H2 and CO, the two detected gases. Hydrogen content may be as high as 7 ppm with $delta$DH2 values ranging from −258texttenthousand to -- 224texttenthousand for sub-pure chloritite and − 140texttenthousand for pure talc. CO content ranges between 3 ppm and 35.3 ppm with very homogeneous $delta$13CCO values between −27.6texttenthousand and − 25.7texttenthousand. This study supports the idea that H2 was produced during experiments by dehydrogenation. The origin of CO remains enigmatic, but its carbon isotope composition suggests a link to the few amounts of graphite documented in chloritite and talc from the deposit. This work also reports extensive hydrogen isotope fractionation between H2 produced by dehydrogenation and both talc and chloritite. Dehydrogenation of phyllosilicates is a potential source term of H2 in numerous magmatic-hydrothermal settings and must thus be accounted for in the budget of the H2 geochemical cycle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Paquet_etal2022,

title = {Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis},

author = {M. Paquet and F. Moynier and T. Yokoyama and al. and L. Piani},

doi = {10.1038/s41550-022-01846-1},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {Nature Astronomy},

abstract = {Initial analyses showed that asteroid Ryugu’s composition is close to CI (Ivuna-like) carbonaceous chondrites (CCs) -- the chemically most primitive meteorites, characterized by near-solar abundances for most elements. However, some isotopic signatures (for example, Ti, Cr) overlap with other CC groups, so the details of the link between Ryugu and the CI chondrites are not yet fully clear. Here we show that Ryugu and CI chondrites have the same zinc and copper isotopic composition. As the various chondrite groups have very distinct Zn and Cu isotopic signatures, our results point at a common genetic heritage between Ryugu and CI chondrites, ruling out any affinity with other CC groups. Since Ryugu’s pristine samples match thesolar elemental composition for many elements, their Zn and Cu isotopic compositions likely represent the best estimates of the solar composition. Earth’s mass-independent Zn isotopic composition is intermediate between Ryugu/CC and non-carbonaceous chondrites (NCs), suggesting a contribution of Ryugu-like material to Earth’s budgets of Zn and other moderately volatile elements.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Mamadou_etal2022,

title = {The Tim Merso"i Basin uranium deposits (Northern Niger): Geochronology and genetic model},

author = {M. M. Mamadou and M. Cathelineau and E. Deloule and L. Reisberg},

doi = {10.1016/j.oregeorev.2022.104905},

year  = {2022},

date = {2022-01-01},

journal = {Ore Geology Reviews},

volume = {145},

pages = {104905},

abstract = {The Tim Merso"i uranium province in northern Niger is one of the world’s largest uranium reserves and fourthhighest uranium producer. The main uranium deposits (Arlit, Akouta, and Imouraren) are located in continental siliciclastic formations. The regional north--south-trending fault (the Arlit Fault) strongly controls them, as well as secondary discontinuity networks oriented NNE-SSW, ENE-WSW, and WNW-ESE. The Arlit and Akouta uranium-ores are hosted in reduced Carboniferous formations and occur as reduced U4+ phase mineralizations.Besides, the Imouraren deposit is hosted by an oxidized Jurassic formation with a predominance of U6+ silicate and vanadate minerals and relics of reduced mineralization. New U-Pb SIMS data have been obtained on the three deposits, and the results reveal two main stages of uranium deposition and ore metallogenesis. (i) the 90--145 Ma Lower Cretaceous mineralization is related to a significant tectonothermal event, synchronous with the Atlantic rifting that induced the deformation and brine migration from Triassic formations. Primary uraninite and chalcocite are formed by fluid mixing in a reduced environment at that stage at a depth of 1 km at less at a temperature 115--150 ◦C, hotter than that of the reservoir. (ii) During later Cenozoic exhumation of the basin, a series of remobilizations of primary uranium stock resulted in the formation of much younger uraninites under reduced conditions at Arlit-Akouta around 50 Ma. At Imouraren, younger uraninites formed between 34 and 8 Ma under locally reduced conditions, and were followed by secondary U-minerals from 21 Ma up to 3--1.6 Ma during supergene events. These ages are close or superimposed with the main oxidation stages, affecting West Africa during the Cenozoic, and attest of water table oscillations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Krmer-Ruggiu_etal2022,

title = {Detection of incipient aqueous alteration in carbonaceous chondrites},

author = {L. Kr\"{a}mer-Ruggiu and B. Devouard and J. Gattacceca and L. Bonal and H. Leroux and J. Eschrig and D. Borschneck and A. J. King and P. Beck and Y. Marrocchi and V. Debaille and R. D. Hanna and O. Grauby},

doi = {10.1016/j.gca.2022.09.020},

year  = {2022},

date = {2022-01-01},

journal = {Geochimica et Cosmochimica Acta},

volume = {336},

pages = {308--331},

abstract = {We discuss if the detection of aqueous alteration depends on the techniques that are used. We apply different methods to estimate the extent of aqueous alteration on four ungrouped carbonaceous chondrites showing limited aqueous alteration and thermal metamorphism: Chwichiya 002, El M\'{e}dano (EM) 200, Northwest Africa (NWA) 12957 and NWA 11750, classified as C3 or C3.00-ung. The aim is to propose a reliable methodology to identify the most primitive chondrites. Chwichiya 002, NWA 11750 and NWA 12957 display very primitive matrices and could be amongst the most primitive chondrites currently known, similar to the least altered lithologies of the CM chondrites Paris (CM2.9) and Asuka (A) 12085 (CM2.8), A 12236 (CM2.9) and A 12169 (CM3.0). The structure of organic matter and Cr2O3 in ferroan olivines show that the four meteorites have been less heated than the least metamorphosed standard/reference type 3 chondrite, Semarkona (LL3.00), with Chwichiya 002, NWA 12957 and NWA 11750 similar to the CO3.0 s, Acfer 094 (C2-ung) and Paris meteorites. Chwichiya 002 and NWA 12957 show similar alteration phases and degree of alteration, with high abundances of amorphous material with embedded metal and sulfide, resembling Glass with Embedded Metal and Sulfide (GEMS)-like materials, and tochilinite-cronstedtite intergrowths (TCIs) as the major alteration phases. The matrix in NWA 11750 contains aggregates of nanoscale olivine crystals and abundant carbonates, observed as micrometer-sized carbonate veins surrounding chondrules, and as nanoscale carbonates mixed with the fine-grained materials. It also contains abundant grains of metal and a low abundance of phyllosilicates. El Medano 200 shows a high abundance of magnetite (\^{a}`u10 vol%), nanoscale phyllosilicates, troilite, and organic matter. The variability of the secondary alteration phases in the meteorites suggests different alteration mechanisms, likely depending on both the starting composition of the meteorites and the composition of the fluids of alteration.Scanning and transmission electron microscopy (SEM and TEM) allow the identification of primitive phases and the composition and spatial distribution of the secondary phases. X-ray diffraction (XRD) can detect alteration products, including some amorphous phases, although this is limited by the small coherence domains of small TCIs and other phyllosilicates. Transmission infrared (IR) spectroscopy can detect phyllosilicate and carbonate, but is ineffective for the detection of amorphous phases, metal, or sulfide. Both matrix defocused electron microprobe analyses (EMPA) and thermogravimetric analysis (TGA) allow detection of hydrated minerals, such as phyllosilicates and carbonates, but are strongly influenced by the presence of organic matter and do not reflect the overall alteration state of a meteorite. We conclude that the assessment of the primitivity of a chondrite is highly technique dependent. We propose a combination of XRD and the Cr2O3 in ferroan olivines or Raman spectroscopy for a rapid characterization of the alteration state of a chondrite and the detection of the most primitive meteorites. Finally, the combination of XRD and TEM allows for the detection of all primary and secondary phases and represents an ideal methodology for the characterization and detailed study of primitive chondrites and the different types of incipient aqueous alteration.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kawasaki_etal2022,

title = {Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2},

author = {N. Kawasaki and K. Nagashima and N. Sakamoto and al. and L. Piani},

doi = {10.1126/sciadv.ade2067},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {Science Advances},

volume = {8},

number = {50},

abstract = {The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16O-rich (associated with refractory inclusions) and 16O-poor (associated with chondrules). Both the 16O-rich and 16O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16O-rich to 16O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}