Komatiite magmas and nickel sulfide deposits: a lithogeochemical comparison of variably endowed terranes

摘要

We have compiled an extensive database of whole-rock major and trace element geochemistry for a number of Archaean greenstone belts and Proterozoic orogenic belts containing komatiites and komatiitic basalts: the Eastern Goldfields Superterrane and the Forrestania - Lake Johnston-Ravensthorpe belts of the Yilgarn Craton (Barnes, et al., 2004; Barnes, et al., 2007; Perring, et al., 1996); the Cape Smith and Thompson Belts of the Circum-Superior orogeny (Layton-Matthews, et al., 2003; Layton-Matthews, et al., 2007; Lesher, 2007); and the Abitibi greenstone belt of the Superior Craton (Sproule, et al., 2002; Sproule, et al., 2005). All of these belts contain nickel sulfide deposits associated with olivine-rich cumulates from komatiitic magmas. In each case we have a sufficiently extensive body of data to be able to estimate the relative proportions of different rock types, based on lithogeochemistry. We compare these datasets with a global komatiite database which includes data from largely barren komatiite sequences worldwide.