Ultramafic and carbonate-rich rocks juxtaposed in an oceanic sedimentary mélange that experienced Alpine subduction (Champorcher, Aosta Valley, Italy) show evidence of metasomatic alteration at their contacts. The reactions occurred these contacts afford assessment the sources compositions fluids associated with alteration, degree scale which mobilized carbon. At contacts, display calcite repla...

UNDERSTANDING CARBONATE AND SERPENTINE ON MARS. B.L. Ehlmann, P.B. Kelemen, P. Pinet, J.F. Mustard, P. Launeau, G. Ceuleneer. Geological & Planetary Sciences, California Institute of Technology, Jet Propulsion Laboratory, Lamont-Doherty Earth Observatory, Columbia University, IRAP/CNRS, OMP, Toulouse, Geological Sciences, Brown University, Laboratoire de Planétologie et Géodynamique, UMR-CNRS, ...

Qara Aqaj titanium potential is one of the two major known titanium resources in Iran. The main host rocks of the ore body are ultramafics including wehrlite and lherzolite with minor clinopyroxenite. Qara Aqaj intrusion is composed mainly of ultramafic-mafic rocks, layered gabbro, diorite, microdiorite and some monzonite and alkali syenite. This intrusion has intruded the basement complex (amp...

The aqueous alteration of ultramafic rocks through serpentinization liberates mantle carbon and reducing power. Serpentinization occurs in numerous settings on present day Earth, including subduction zones, mid-ocean ridges, and ophiolites and has extended far into Earth’s history, potentially contributing to the origins and early evolution of life. Serpentinization can provide the energy and r...

Among the deep-sea hydrothermal vent sites discovered in the past 30 years, Lost City on the Mid-Atlantic Ridge (MAR) is remarkable both for its alkaline fluids derived from mantle rock serpentinization and the spectacular seafloor carbonate chimneys precipitated from these fluids. Despite high concentrations of reduced chemicals in the fluids, this unique example of a serpentinite-hosted hydro...

Seawater is constantly circulating through oceanic basement as a low-temperature hydrothermal fluid (<150 degrees C). In cases when ultramafic rocks are exposed to the fluids, for instance during the initial phase of subduction, ferromagnesian minerals are altered in contact with the water, leading to high pH and formation of secondary magnesium hydroxide, among other--brucite, that may scaveng...

The eucrites and diogenites are meteorites that probably originate from asteroid 4-Vesta. The upper part of the crust of this body is certainly composed of eucrites which are basaltic or gabbroic rocks. Diogenites are ultramafic cumulates whose relationships with eucritic lithologies are unknown. Here, we show that the orthopyroxenes of some diogenites display very deep negative Eu anomalies (E...

Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of t...