Iron isotopic systematics of oceanic basalts
نویسندگان
چکیده
The iron isotopic compositions of 93 well-characterized basalts from geochemically and geologically diverse mid-ocean ridge segments, oceanic islands and back arc basins were measured. Forty-three MORBs have homogeneous Fe isotopic composition, with dFe ranging from +0.07& to +0.14& and an average of +0.105 ± 0.006& (2SD/ p n, n = 43, MSWD = 1.9). Three back arc basin basalts have similar dFe to MORBs. By contrast, OIBs are slightly heterogeneous with dFe ranging from +0.05& to +0.14& in samples from Koolau and Loihi, Hawaii, and from +0.09& to +0.18& in samples from the Society Islands and Cook-Austral chain, French Polynesia. Overall, oceanic basalts are isotopically heavier than mantle peridotite and pyroxenite xenoliths, reflecting Fe isotope fractionation during partial melting of the mantle. Iron isotopic variations in OIBs mainly reflect Fe isotope fractionation during fractional crystallization of olivine and pyroxene, enhanced by source heterogeneity in Koolau samples. 2012 Elsevier Ltd. All rights reserved.
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تاریخ انتشار 2013