Title: PGE Geochemistry of Alkaline Ultramafic Dykes in Southwestern Guizhou Province,China
Abstract: Studies on the petrogenesis of alkaline ultramafic dykes are helpful to understand the formation of the gold deposits widely distributed in southwestern Guizhou Province,China.The platinum-group elements(PGE) are sensitive indicators of the petrogenesis(e.g.,partial melting and silicate fractionation) of mafic-ultramafic rocks.Thus,in this paper,contents of Ni,Cu and PGE(Ir,Ru,Rh,Pt and Pd) were measured by using isotope dilution(ID)-ICP-MS with an improved Carius tube.The studied samples are characterized by low PGE contents,high Cu/Pd(11903—60210) ratios and positive slope in the primitive mantle normalized patterns.Synthetic and comparative studies on the PGE indicate that the ultramafic rocks were derived from low-degree partial melting of the MORB-like mantle.These dyke rocks were formed by the crystallization of the S-unsaturated magma,which had not experienced obvious sulfide segregation.The primary magma of the ultramafic rocks,however,underwent extensive fractionation of clinopyroxene,olivine,Ti-bearing phases(e.g.,rutile,ilmenite,titanite) and apatite,prior to emplacement.In addition,the Longyao ultramafic dykes experienced differentiation of chromite during primary magma ascent.
Publication Year: 2010
Publication Date: 2010-01-01
Language: en
Type: article
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Cited By Count: 2
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