Multi-isotopic (Cr, Pb, Li, Nd) Characterisation of Cr-bearing rocks and alteration products from different geological environments
Résumé
Chromium exists in two oxidation states (Cr(III)/Cr(VI)) and present four stable isotopes (50Cr, 52Cr, 53Cr, 54Cr). Cr isotopic variations have been correlated in surface processes with change in redox conditions, and used as a redox proxy in different geochemical reservoirs (Ellis et al., 2002; Frei et al., 2009). In this context, Schoenberg et al. (2008) emphasized the primary importance of background knowledge of Cr isotope composition of rocks reservoirs, as a starting point of the global chromium cycle. So far, only few studies have reported Cr isotope signature of rock reservoirs, with Schoenberg et al. reporting a uniform 53Cr/52Cr isotope ratio in mantle derived rocks Here, we are reporting Cr isotope compositions, along with chemical concentrations of major and trace elements of a new set of Cr-bearing rocks. A representative set of structural chromite and altered chromite of different textures have been selected from two characteristic geological environments.