Articles

Webinaire LGO/GM de Yoann COPARD (M2C, Université de Caen)

La matière organique comme traceur de l’érosion continentale

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Conceptual view of various particulate organic carbon (POC) sources in a catchment (from the Bleone river system, upstream Digne les Bains, Alpes de Haute Provence, France). POCa: aquatic POC as the autochthonous POC for the river system. POCp (petrogenic POC), POCs (soil POC), POCrw (reworked POC), both considered as allochtonous and
respectively originating from: outcropping rocks, soils, superficial formations. The two colour codes for POCrwcorrespond to POC older (grey) and younger (sepia) than 60 ky BP. Red  circle corresponds to a theoretical coring site and POC is the sedimentary POC. From Copard et al., submitted (picture from Goolge earth).

 

Webinaire GM/LGO de Zhiteng YU (Géosciences Marines, Ifremer, Brest)

Semibrittle seismic deformation in high-temperature mantle
mylonite shear zone along the Romanche transform fault

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Oceanic transform faults represent the first-order discontinuities along mid-ocean ridges, host large earthquakes, and induce extreme thermal gradients in lithosphere. However, the thermal structure along transform faults and its effects on earthquake generation are poorly understood. In this study, we report the presence of a 10-15-km-thick in-depth band of microseismicity in 10-34 km depth range associated with a high-temperature (700-900°C) mantle below the brittle lithosphere along the Romanche mega-transform fault in the equatorial Atlantic Ocean. The occurrence of the shallow 2016 Mw 7.1 super-shear rupture earthquake and these deep microearthquakes indicate that although large earthquakes along transform faults occur in the upper brittle lithosphere, a significant amount of deformation is accommodated in the semi-brittle mylonitic mantle that resides at depths below the 600°C isotherm. We also observe a rapid westward deepening of this band of seismicity indicating a strong heterogeneity along the transform fault

Webinaire GM/LGO de Romain PELLEN (Ifremer)

The Occidental Mediterranean Laboratory:

linking sediment yields, paleoceanography, heritage, vertical motion and plate tectonics, and sea-level change

 

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Séminaire de Joti ROUILLARD (CSIC—Universidad de Granada)

Recognizing life in extraterrestrial environments:
current problems and possible solutions

 

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Séminaire de Marine Paquet (Institut de Physique du Globe de Paris)

Global oceanic mantle highly siderophile element composition from abyssal peridotites

 

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