2021
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Klaessens, D., Reisberg, L., Jousselin, D., Team, Oman Drilling Project Science Highly siderophile element and Os isotope results from the structurally atypical Batin dunite in the Wadi Tayin massif of the Oman ophiolite (Article de journal) Dans: JGR Solid Earth, 2021. @article{Klaessens_etal2021,
title = {Highly siderophile element and Os isotope results from the structurally atypical Batin dunite in the Wadi Tayin massif of the Oman ophiolite},
author = {D. Klaessens and L. Reisberg and D. Jousselin and Oman Drilling Project Science Team},
doi = {10.1029/2021JB021977},
year = {2021},
date = {2021-01-01},
journal = {JGR Solid Earth},
abstract = {Dunites in ophiolites form by pyroxene dissolution and olivine precipitation during meltperidotite interaction. We present structural and geochemical data on peridotites from the Batin region (Wadi Tayin massif) of the Oman ophiolite, where an exceptionally large (�`u9.5 km long) dunite body was sampled by the ICDP Oman Drilling Project (BA4A borehole). 900--1,200 m beneath the petrological Moho, this dunite is overlain by harzburgite hosting pyroxene-depleted and pyroxene-rich bands. Highly siderophile elements (HSEs) and Os isotopes, excellent tracers of melt flow through peridotites, were measured in dunites and interspersed harzburgites from BA4A borehole. The Batin dunite is structurally and chemically distinct from dunites from the Moho Transition Zone and basal section of the ophiolite, resembling instead sparse dunite veins in the main mantle section. Batin dunites have fairly uniform Os, Ir, and Ru abundances, but Pd and Pt contents increasing with depth. One deep dunite sample has initial 187Os/188Os more radiogenic than MORB. Though the limited number of data demands prudence, we suggest that the Batin dunite formed from a large pulse of radiogenic melts, whose flow was impeded �`u1,200 m below the Moho. As these melts ascended, they may have lost their radiogenic character and relative Pt and Pd enrichment through interaction with peridotites, which have much higher HSE contents than melts. Such interaction would also diminish the under-saturation in pyroxene of the melts, eliminating their capacity to sufficiently dissolve the pyroxene of the host harzburgite to form dunite, thus explaining the upper limit of the dunite at �`u900 m.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dunites in ophiolites form by pyroxene dissolution and olivine precipitation during meltperidotite interaction. We present structural and geochemical data on peridotites from the Batin region (Wadi Tayin massif) of the Oman ophiolite, where an exceptionally large (�`u9.5 km long) dunite body was sampled by the ICDP Oman Drilling Project (BA4A borehole). 900--1,200 m beneath the petrological Moho, this dunite is overlain by harzburgite hosting pyroxene-depleted and pyroxene-rich bands. Highly siderophile elements (HSEs) and Os isotopes, excellent tracers of melt flow through peridotites, were measured in dunites and interspersed harzburgites from BA4A borehole. The Batin dunite is structurally and chemically distinct from dunites from the Moho Transition Zone and basal section of the ophiolite, resembling instead sparse dunite veins in the main mantle section. Batin dunites have fairly uniform Os, Ir, and Ru abundances, but Pd and Pt contents increasing with depth. One deep dunite sample has initial 187Os/188Os more radiogenic than MORB. Though the limited number of data demands prudence, we suggest that the Batin dunite formed from a large pulse of radiogenic melts, whose flow was impeded �`u1,200 m below the Moho. As these melts ascended, they may have lost their radiogenic character and relative Pt and Pd enrichment through interaction with peridotites, which have much higher HSE contents than melts. Such interaction would also diminish the under-saturation in pyroxene of the melts, eliminating their capacity to sufficiently dissolve the pyroxene of the host harzburgite to form dunite, thus explaining the upper limit of the dunite at �`u900 m. |
Klaessens, D., Resiberg, L., Jousselin, D., Godard, M. Osmium isotope evidence for rapid melt migration towards the Moho in the Oman ophiolite (Article de journal) Dans: Earth and Planetary Science Letters, vol. 572, p. 117111, 2021. @article{Klaessens_etal2021_2,
title = {Osmium isotope evidence for rapid melt migration towards the Moho in the Oman ophiolite},
author = {D. Klaessens and L. Resiberg and D. Jousselin and M. Godard},
doi = {10.1016/j.epsl.2021.117111},
year = {2021},
date = {2021-01-01},
journal = {Earth and Planetary Science Letters},
volume = {572},
pages = {117111},
abstract = {The oceanic crust, covering two-thirds of the Earthtextquoterights surface, is formed along mid-oceanic ridges by crystallization at shallow levels of melts formed at depth by partial melting of mantle peridotite. Yet, the process of melt transport to the ridge axis remains poorly understood. Ophiolites, which provide a window into the uppermost mantle, contain dunite bodies often interpreted as relics of melt flow conduits, formed by pyroxene dissolution during melt-peridotite interaction. Here, we present structural and geochemical data on peridotites from the southeastern Oman ophiolite where three types of dunite, corresponding to the Moho transition zone (MTZ), the main and basal mantle sections, are identified. We focus on osmium isotopes, which are particularly well-adapted to tracing melt flow through peridotites. Osmium isotope signatures from host harzburgites accord with abyssal peridotite values and do not vary systematically with setting. In contrast, dunite Os compositions depend on structural context. Basal dunites display compositions similar to harzburgite values, while MTZ dunites have highly radiogenic compositions similar to those of the overlying crust, requiring extensive interaction with melts more radiogenic than MORB. Modeling shows that melts percolating through and equilibrating with dunite channels would acquire unradiogenic compositions, inconsistent with the observed Os signatures of MTZ dunites and lower crust. Thus, our findings require melt transport without equilibration with dunite or harzburgite, arguing for rapid or at least chemically isolated melt migration from the mantle source to the Moho.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oceanic crust, covering two-thirds of the Earthtextquoterights surface, is formed along mid-oceanic ridges by crystallization at shallow levels of melts formed at depth by partial melting of mantle peridotite. Yet, the process of melt transport to the ridge axis remains poorly understood. Ophiolites, which provide a window into the uppermost mantle, contain dunite bodies often interpreted as relics of melt flow conduits, formed by pyroxene dissolution during melt-peridotite interaction. Here, we present structural and geochemical data on peridotites from the southeastern Oman ophiolite where three types of dunite, corresponding to the Moho transition zone (MTZ), the main and basal mantle sections, are identified. We focus on osmium isotopes, which are particularly well-adapted to tracing melt flow through peridotites. Osmium isotope signatures from host harzburgites accord with abyssal peridotite values and do not vary systematically with setting. In contrast, dunite Os compositions depend on structural context. Basal dunites display compositions similar to harzburgite values, while MTZ dunites have highly radiogenic compositions similar to those of the overlying crust, requiring extensive interaction with melts more radiogenic than MORB. Modeling shows that melts percolating through and equilibrating with dunite channels would acquire unradiogenic compositions, inconsistent with the observed Os signatures of MTZ dunites and lower crust. Thus, our findings require melt transport without equilibration with dunite or harzburgite, arguing for rapid or at least chemically isolated melt migration from the mantle source to the Moho. |
Jousselin, D., Nicolas, A., Boudier, F., Reisberg, L., Henri, M., Nicolle, M. Formation of the Moho transition zone in the Oman ophiolite, and comparison with sub-Moho melt lenses at fast spreading ridges (Article de journal) Dans: Tectonophysics, vol. 821, p. 229148, 2021. @article{Jousselin_etal2021,
title = {Formation of the Moho transition zone in the Oman ophiolite, and comparison with sub-Moho melt lenses at fast spreading ridges},
author = {D. Jousselin and A. Nicolas and F. Boudier and L. Reisberg and M. Henri and M. Nicolle},
doi = {10.1016/j.tecto.2021.229148},
year = {2021},
date = {2021-01-01},
journal = {Tectonophysics},
volume = {821},
pages = {229148},
abstract = {Our knowledge of melt distribution in the lower crust and upper mantle at oceanic fast spreading centers is very limited. Evidence of melt accumulation, sometimes away from the axis, has been imaged and interpreted at the Moho of the East Pacific Rise ; but the detailed structures of these deep magma lenses remains much more difficult to unveil than that of the shallow axial melt lens at the top of the plutonic crust. Ophiolites offer on-land sections of oceanic lithosphere that can complement marine geological and geophysical observations. We present results of a geological survey of the Moho transition zone at a paleospreading center in the Oman ophiolite. We find that the thickness of this dunite-rich horizontal layer increases from a few meters at the axis to hundreds of meters 6km away from the axis, and is reduced to a few meters 2--3 km further away. The base of the Moho transition zone contains dunite and very depleted harzburgite with isotropic plagioclase and clinopyroxene impregnations, and stockwork-like magmatic breccia, indicative of episodic high melt fractions. We conclude that the melt-free dunite horizontal layer may stop the progression of ascending melt ; this lead to melt accumulation within the uppermost harzburgite beneath the Moho transition zone and forms the isotropic impregnations. As the melt dissolves the harzburgite orhtopyroxene, and is flushed to the top of the MTZ though the breccia, it leaves new dunite at the base of the Moho transition zone. Repetition of this process renders the Moho transition zone thicker as it moves away from the ridge axis, until it leaves the main area of mantle melt delivery. Then, tectonic thinning and intrusion of parts of the MTZ into the lower crust reduce the MTZ thickness. These processes seem coherent with several marine geophysical observations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Our knowledge of melt distribution in the lower crust and upper mantle at oceanic fast spreading centers is very limited. Evidence of melt accumulation, sometimes away from the axis, has been imaged and interpreted at the Moho of the East Pacific Rise ; but the detailed structures of these deep magma lenses remains much more difficult to unveil than that of the shallow axial melt lens at the top of the plutonic crust. Ophiolites offer on-land sections of oceanic lithosphere that can complement marine geological and geophysical observations. We present results of a geological survey of the Moho transition zone at a paleospreading center in the Oman ophiolite. We find that the thickness of this dunite-rich horizontal layer increases from a few meters at the axis to hundreds of meters 6km away from the axis, and is reduced to a few meters 2--3 km further away. The base of the Moho transition zone contains dunite and very depleted harzburgite with isotropic plagioclase and clinopyroxene impregnations, and stockwork-like magmatic breccia, indicative of episodic high melt fractions. We conclude that the melt-free dunite horizontal layer may stop the progression of ascending melt ; this lead to melt accumulation within the uppermost harzburgite beneath the Moho transition zone and forms the isotropic impregnations. As the melt dissolves the harzburgite orhtopyroxene, and is flushed to the top of the MTZ though the breccia, it leaves new dunite at the base of the Moho transition zone. Repetition of this process renders the Moho transition zone thicker as it moves away from the ridge axis, until it leaves the main area of mantle melt delivery. Then, tectonic thinning and intrusion of parts of the MTZ into the lower crust reduce the MTZ thickness. These processes seem coherent with several marine geophysical observations. |
2020
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Kelemen, P., Matter, J. M., Teagle, D. A. H., Coggon, J. A., Team, Oman Drilling Project Science, France, L., Boulanger, M., Jousselin, D., Klaessens, D., Reisberg, L. Proceedings of the Oman Drilling Project (Article de journal) Dans: College Station, TX (International Ocean Discovery Program, 2020. @article{Kelemen_etal2020,
title = {Proceedings of the Oman Drilling Project},
author = {P. Kelemen and J. M. Matter and D. A. H. Teagle and J. A. Coggon and Oman Drilling Project Science Team and L. France and M. Boulanger and D. Jousselin and D. Klaessens and L. Reisberg},
doi = {10.14379/OmanDP.proc.2020},
year = {2020},
date = {2020-01-01},
journal = {College Station, TX (International Ocean Discovery Program},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2017
|
Nicolas, A., Meshi, A., Boudier, F., Jousselin, D., Muceku, B. Mylonites in ophiolite of Mirdita (Albania): Oceanic detachment shear zone (Article de journal) Dans: Geosphere, vol. 13, no. 1, p. 136–154, 2017. @article{Nicolas_etal2017,
title = {Mylonites in ophiolite of Mirdita (Albania): Oceanic detachment shear zone},
author = {A. Nicolas and A. Meshi and F. Boudier and D. Jousselin and B. Muceku},
year = {2017},
date = {2017-01-01},
journal = {Geosphere},
volume = {13},
number = {1},
pages = {136--154},
abstract = {The northern Mirdita ophiolite massifs in Albanian Dinarides formed at a slow-spreading ridge, active during the Jurassic (160--165 Ma). They share a common horizontal Jurassic--Lower Cretaceous sedimentary cover showing that they were not deeply and intrinsically affected by later Alpine thrusting. The western massifs of Mirdita, first oceanic core complex (OCC) and detachment shear zone described in ophiolites, compare with OCCs in slow-spreading ridges and provide continuous exposure of the deep internal structure of this system, revealing its kinematics, thanks to detailed structural mapping in peridotites and gabbros. The Mirdita detachments root in the Moho transition zone (MTZ), a weak zone at the top of asthenospheric mantle, where basaltic melts impregnate dunites. The OCC domes are plagioclase-amphibole--bearing mylonitic peridotites, �`u400 m thick, grading downward within 200 m to harzburgitic mantle. The mylonitic detachments crossed Moho beneath a NNE-SSW--trending ridge. On the western side of OCC domes, the hanging wall of the ridge, crustal gabbros, and basalts are still preserved, despite being deeply affected by hydrothermal alteration. From there, the partially molten MTZ was detached as a shear zone, mixing with lower gabbros. The OCC emerged, migrating upsection and eastward over 5 km. Finally, the OCC front is observed in hornblende-rich syntectonic mylonites derived from upper gabbros and from the overlying former lid. Serpentinization is static within these mylonites. A low-temperature detachment fault is expressed as a sheared antigoritic m\'{e}lange at the margin of the mylonitic shear zone. Asthenospheric flow in the harzburgitic mantle beneath the ridge of origin has been preserved below the OCC rooting. The dominant asthenospheric flow direction trends parallel to the ridge axis. This mantle flow rotates over 200 m into the low-temperature mylonitic detachments, where OCC motion turns transversal to the ridge. Crystal preferred orientation measurements on six samples point to brown hornblende crystal growth during mylonitic flow and illustrate the change of olivine intra-crystalline slip system in mylonites compared to porphyroclastic harzburgite.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The northern Mirdita ophiolite massifs in Albanian Dinarides formed at a slow-spreading ridge, active during the Jurassic (160--165 Ma). They share a common horizontal Jurassic--Lower Cretaceous sedimentary cover showing that they were not deeply and intrinsically affected by later Alpine thrusting. The western massifs of Mirdita, first oceanic core complex (OCC) and detachment shear zone described in ophiolites, compare with OCCs in slow-spreading ridges and provide continuous exposure of the deep internal structure of this system, revealing its kinematics, thanks to detailed structural mapping in peridotites and gabbros. The Mirdita detachments root in the Moho transition zone (MTZ), a weak zone at the top of asthenospheric mantle, where basaltic melts impregnate dunites. The OCC domes are plagioclase-amphibole--bearing mylonitic peridotites, �`u400 m thick, grading downward within 200 m to harzburgitic mantle. The mylonitic detachments crossed Moho beneath a NNE-SSW--trending ridge. On the western side of OCC domes, the hanging wall of the ridge, crustal gabbros, and basalts are still preserved, despite being deeply affected by hydrothermal alteration. From there, the partially molten MTZ was detached as a shear zone, mixing with lower gabbros. The OCC emerged, migrating upsection and eastward over 5 km. Finally, the OCC front is observed in hornblende-rich syntectonic mylonites derived from upper gabbros and from the overlying former lid. Serpentinization is static within these mylonites. A low-temperature detachment fault is expressed as a sheared antigoritic mélange at the margin of the mylonitic shear zone. Asthenospheric flow in the harzburgitic mantle beneath the ridge of origin has been preserved below the OCC rooting. The dominant asthenospheric flow direction trends parallel to the ridge axis. This mantle flow rotates over 200 m into the low-temperature mylonitic detachments, where OCC motion turns transversal to the ridge. Crystal preferred orientation measurements on six samples point to brown hornblende crystal growth during mylonitic flow and illustrate the change of olivine intra-crystalline slip system in mylonites compared to porphyroclastic harzburgite. |
2016
|
Nicolle, M., Jousselin, D., Reisberg, L., Bosch, D., Stephant, A. Major and trace element and Sr and Nd isotopic results from mantle diapirs in the Oman ophiolite: Implications for off-axis magmatic processes (Article de journal) Dans: Earth and Planetary Science Letters, vol. 437, p. 138–149, 2016. @article{Nicolle_etal2016,
title = {Major and trace element and Sr and Nd isotopic results from mantle diapirs in the Oman ophiolite: Implications for off-axis magmatic processes},
author = {M. Nicolle and D. Jousselin and L. Reisberg and D. Bosch and A. Stephant},
doi = {10.1016/j.epsl.2015.12.005},
year = {2016},
date = {2016-01-01},
journal = {Earth and Planetary Science Letters},
volume = {437},
pages = {138--149},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2012
|
Ford, M., Rohais, S., Williams, E. A., Bourlange, S., Jousselin, D., Backert, N., Malartre, F. Tectono-sedimentary evolution of the western Corinth rift (Central Greece) (Article de journal) Dans: Basin Research, p. 1–23, 2012. @article{Ford_etal2012,
title = {Tectono-sedimentary evolution of the western Corinth rift (Central Greece)},
author = {M. Ford and S. Rohais and E. A. Williams and S. Bourlange and D. Jousselin and N. Backert and F. Malartre},
doi = {10.1111/j.1365-2117.2012.00550.x},
year = {2012},
date = {2012-01-01},
journal = {Basin Research},
pages = {1--23},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Jousselin, D., Morales, Luiz F. G., Nicolle, M., Stephant, A. Gabbro layering induced by simple shear in the Oman ophiolite Moho transition zone (Article de journal) Dans: Earth and Planetary Science Letters, vol. 331-332, p. 55–66, 2012. @article{Jousselin_etal2012,
title = {Gabbro layering induced by simple shear in the Oman ophiolite Moho transition zone},
author = {D. Jousselin and Luiz F. G. Morales and M. Nicolle and A. Stephant},
doi = {10.1016/j.epsl.2012.02.022},
year = {2012},
date = {2012-01-01},
journal = {Earth and Planetary Science Letters},
volume = {331-332},
pages = {55--66},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2009
|
Toomey, D. R., Jousselin, D., A., R., Dunn, Mantle skewness and ridge segmentation Toomey et al. reply (Article de journal) Dans: Nature, vol. 458, p. E12-E13, 2009. @article{Toomey_etal2009,
title = {Mantle skewness and ridge segmentation Toomey et al. reply},
author = {D. R. Toomey and D. Jousselin and R. A. and Dunn},
year = {2009},
date = {2009-01-01},
journal = {Nature},
volume = {458},
pages = {E12-E13},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2007
|
Toomey, D. R., Jousselin, D., Dunn, R. A., Wilcock, W. S. D., Detrick, R. S. Skew of mantle upwelling beneath the East Pacific Rise governs segmentation (Article de journal) Dans: Nature, vol. 446, no. 7134, p. 409–414, 2007. @article{Toomey_etal2007,
title = {Skew of mantle upwelling beneath the East Pacific Rise governs segmentation},
author = {D. R. Toomey and D. Jousselin and R. A. Dunn and W. S. D. Wilcock and R. S. Detrick},
doi = {10.1038/nature05679},
year = {2007},
date = {2007-01-01},
journal = {Nature},
volume = {446},
number = {7134},
pages = {409--414},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2003
|
Jousselin, D., Dunn, R., Toomey, D. R. Modeling the seismic signature of structural data from the Oman Ophiolite: can a mantle diapir be detected beneath the East Pacific Rise? (Article de journal) Dans: Geochemistry Geophysics Geosystems G3, vol. 4, no. 7, p. 8610, 2003. @article{Jousselin_etal2003,
title = {Modeling the seismic signature of structural data from the Oman Ophiolite: can a mantle diapir be detected beneath the East Pacific Rise?},
author = {D. Jousselin and R. Dunn and D. R. Toomey},
doi = {10.1029/2002GC000418},
year = {2003},
date = {2003-01-01},
journal = {Geochemistry Geophysics Geosystems G3},
volume = {4},
number = {7},
pages = {8610},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
