Platinum group elements in the Emeishan large igneous province, SW China: Implications for mantle sources

Abstract

We report concentrations of platinum group elements (PGE: Os, Ir, Ru, Rh, Pt and Pd) for picrite-basalt lavas of the Emeishan large igneous province, SW China. The absolute concentrations of Os in most of the Emeishan picrites are higher than in picrites from ocean islands and other continental flood basalt provinces, and in estimated primitive mantle. A roughly positive correlation between MgO and Cr and Ni, and no overall correlation of Os or Ir with MgO, show that no Cu-Ni sulfide fractionated during differentiation but rather that olivine and chromite fractionated, implying that the initial picritic magma was sulfide-undersaturated. In addition, Os/Ir ratios are unusually high, suggesting that the picritic magmas may have been contaminated by black shales. Modeling shows that a 7% partial melt of primitive mantle containing 0.01 wt% of sulfides can account for the observed Os, Ir and Ru concentrations in the most primitive picrite if the melt is contaminated by 10 wt% of black shale en route to the surface.

Platinum Group Elements (PGE) geochemistry of komatiites and boninites from Dharwar Craton, India: Implications for mantle melting processes

“…PGE compositions of mantle-derived ultramafic-mafic magmas are significant tools to understand their petrogenetic evolution and sulphide saturation history as PGE behaviour and their abundance is controlled by several factors like mantle heterogeneity, enrichment-depletion processes of the mantle, partial mantle melting, melt percolation, sulphide segregation, crystal fractionation, etc. (Zhang et al, 2005;Naldrett, 2010;Mondal, 2008Mondal, , 2011. PGE abundances in mantle derived rocks have been documented by various workers (Pattou et al, 1996;Rëhkamper and Hofmann, 1997;Snow and Schmidt, 1998;Handler and Bennett, 1999;Lorand et al, 1999Lorand et al, , 2000Lorand et al, , 2004Bennett et al, 2000;Lorand and Alard, 2001;Lee, 2002;Luguet et al, 2003;Irvine et al, 2003;Pearson et al, 2004;Dale et al, 2008;Said et al, 2011 and references therein).…”

“…Platinum group elements [PGE: Pt, Pd, Rh, Ir, Os, Ru] show strong chalcophile and siderophile affinity and are therefore considered as sensitive indicators of processes involving segregation and accumulation of sulphide melts from silicate magmas, coremantle differentiation, mantle evolution and magma genesis (Zhang et al, 2005;Mondal, 2011;Zhou et al, 2014). PGE compositions of mantle-derived ultramafic-mafic magmas are significant tools to understand their petrogenetic evolution and sulphide saturation history as PGE behaviour and their abundance is controlled by several factors like mantle heterogeneity, enrichment-depletion processes of the mantle, partial mantle melting, melt percolation, sulphide segregation, crystal fractionation, etc.…”

Platinum group element abundances in the upper continental crust revisited – New constraints from analyses of Chinese loess

“…TBTI = gabbro (n = 1) from the Tianyou intrusion, Tuha basin, NW China (Tang et al, 2011). EIPFB = Continental flood basalts (n = 6) from the Emeishian large igneous province, SW China (Zhang et al, 2005). LBA = basaltic andesites (n = 3), Leiqiong, SE China (Yang et al, 2011).…”

Controls on PGE fractionation in the Emeishan picrites and basalts: Constraints from integrated lithophile–siderophile elements and Sr–Nd isotopes

“…Table S3 is a database we have compiled from the literature (Xiao et al, 2004;Zhang et al, 2005Zhang et al, , 2006Song et al, 2006Song et al, , 2008Song et al, , 2009Wang et al, 2007;. Sample names and locations listed in the database and shown in Fig.…”

“…Many researchers have used whole-rock major and trace element compositions and Sr-Nd-Os isotopes of basalts and picrites (whole-rock MgO > 16 wt.% and lack of olivine spinifex texture) to investigate the last aspect (e.g., Chung and Jahn, 1995;Xu et al, 2001;Song et al, 2001Song et al, , 2008Xiao et al, 2004;Hanski et al, 2004Hanski et al, , 2010Zhang et al, 2006Zhang et al, , 2008Li et al, 2010;Anh et al, 2011). Some researchers have also used PGE as complementary data (Zhang et al, 2005;Song et al, 2006Song et al, , 2009Wang et al, 2007Wang et al, , 2011. The PGE studies are mainly focused on basalts; only four picrite samples from the entire ELIP, one from the et al, Li et al, 2010).…”