Geochemistry of the Madawara Igneous Complex, BundelkhandCraton, Central India: Implications for PGE Metallogeny

Abstract

Abstract The southern part of the Bundelkhand cratoncontains a series of a E-W trending mafic and ultramaficrocks, about 40 km in length and 2–4 km wide, that occuras intrusions within the Bundelkhand Gneissic Complex(BnGC). They are confined between the Madawara-Karitoran and Sonrai-Girar shear zones. Dunite, harzburgite,lherzolite and websterite are the commonly occurringultramafic rocks that have high MgO, Ni, Cr, PGE andlow Al2O3, CaO, K2O, TiO2 and V contents, and showsperidotitic affinity. A distinct trend of crystallization fromperidotite to komatiitic basalt has been inferred from geochemicalplots, which also indicates the occurrence ofat least two varieties among the ultramafic suite of theMadawara ultramafic complex, namely, Group I comprisingdunite, spinel peridotite, harzburgite and lherzolite,and Group II consisting of pyroxenite, websterite andolivine websterite. In several places, the rocks of Group IIhave an intrusive relationship with Group I, and are relativelyenriched in total platinum group elements (PGE ~300 ppb). The discrimination diagrams suggest that thePGE are enriched in low sulphur-fugacity source magma atmoderate to deeper depths by high degree of partial meltingof the mantle.