chapter  19
Organic Analysis of Peridotite Rocks from the Ashadze and Logatchev Hydrothermal Sites
Pages 15

At the bottom of the terrestrial oceans, where tectonic forces separate the lithospheric plates along mid-ocean ridges, the ultramac rocks of the upper-mantle, the peridotites, are exposed to circulating seawater [1]. ey encounter various physico-chemical conditions and the hydrolysis of their silicate constituents, the olivine and pyroxenes minerals, into serpentine, occur at dierent degrees of serpentinization depending on the characteristics of the medium: temperature, pressure, oxygen fugacity, nature and composition of the uid phase, uid ux, pH, rock composition, water:rock ratio [2]. e Mid-Atlantic-Ridge, MAR, is covered with several hydrothermal sites and presents black smoker activity. e active Logatchev site, 14° 45’N-43’N, at a water depth of 2,970 m and the active Ashadze site (12° 58’N, 4,080 m) are located on an ultramac geological environment of serpentinized peridotite rocks, while the Krasnov site (16° 38’N), discovered with the Ashadze site during the 2007 French-Russian Serpentine cruise [3] is inactive and located on a basaltic environment. Ultramac environments seem enriched in Cu and Zn content compared to the basaltic ones [3].