Cr-spinel records metasomatism not petrogenesis of mantle rocks
MetadataShow full item record
Funding and Sponsorship
Mantle melts provide a window on processes related to global plate tectonics. The composition of chromian spinel (Cr-spinel) from mafic-ultramafic rocks has been widely used for tracing the geotectonic environments, the degree of mantle melting and the rate of mid-ocean ridge spreading. The assumption is that Cr-spinel’s core composition (Cr# = Cr/(Cr + Al)) is homogenous, insensitive to post-formation modification and therefore a robust petrogenetic indicator. However, we demonstrate that the composition of Cr-spinel can be modified by fluid/melt-rock interactions in both sub-arc and sub-mid oceanic mantle. Metasomatism can produce Al-Cr heterogeneity in Cr-spinel that lowers the Cr/Al ratio, and therefore modifies the Cr#, making Cr# ineffective as a geotectonic and mantle melting indicator. Our analysis also demonstrates that Cr-spinel is a potential sink for fluid-mobile elements, especially in subduction zone environments. The heterogeneity of Cr# in Cr-spinel can, therefore, be used as an excellent tracer for metasomatic processes.
Showing items related by title, author, creator and subject.
Paleoproterozoic formation age for the Siberian cratonic mantle: Hf and Nd isotope data on refractory peridotite xenoliths from the Udachnaya kimberliteDoucet, Luc-Serge; Ionov, D.; Golovin, A. (2015)© 2014 Elsevier B.V. The formation age of the Siberian cratonic mantle is not well established as yet. Re-Os data on various mantle-derived materials have shown that it contains Archaean components, but the reported ...
Reworking of Archean mantle in the NE Siberian craton by carbonatite and silicate melt metasomatism: Evidence from a carbonate-bearing, dunite-to-websterite xenolith suite from the Obnazhennaya kimberliteIonov, D.; Doucet, Luc; Xu, Y.; Golovin, A.; Oleinikov, O. (2018)The Obnazhennaya kimberlite in the NE Siberian craton hosts a most unusual cratonic xenolith suite, with common rocks rich in pyroxenes and garnet, and no sheared peridotites. We report petrographic and chemical data for ...
Doucet, Luc-Serge; Mattielli, N.; Ionov, D.; Debouge, W.; Golovin, A. (2016)We present new Zn elemental and isotope data on seventeen fertile and refractory mantle peridotite xenoliths. Eleven fertile peridotites are garnet and spinel lherzolites from Vitim and Tariat (Siberia and Mongolia) and ...