Spinifex Textured Komatiite from Badampahar-Gorumahisani Schist Belt, Mayurbhanj District, Orissa

Spinifex Textured Peridotitic Komatiite (STPK) has been identified in the southern part of Badampahar- Gorumahisani schist belt from the Mid-Archaean granite-greenstone sequence of Singhbhum-Orissa craton. Spectacular field outcrop of large tabular stacked plate olivine pseudomorphs with herringbone to haphazardly oriented book-like structure is located in Patharkata area (22"05'00"N:86°11'50"E). Petrographically, the STPK comprises olivine (completely altered to serpentine), tremolite, chlorite, talc, carbonate, magnetite and glass. Retention of primary skeletal texture, lack of metamorphic cleavage and largely pseudomorphous alteration pattern point to possible syn-eruptional hydration. Their major element chemistry conforms well with that of STPK of Barberton belt (3450 Ma) and reflects an Aldepleted signature. This volcanics-dominated curvilinear Badampahar-Gorumahisani belt has been intruded undoubtedly by the latest phase (3000 Ma) of Singhbhum granite (SBG) and possibly by a still earlier phase of SBG (3300 Ma). No data on lower age limit is available. Major element chemistry of thc Archaean komatiites, occurring in the Badampahar Gorumahisani schist belt, suggests that they have been derived from mantle source and under extensional regime, erupted in a subaqueous (oceanic) environment.