Geochemistry and Detrital Modes of Sandstone From Barakar Formation in Mand Valley Basin, Chhattisgarh, India: Implications for Provenance, Tectonic Setting and Paleoweathering

摘要

Geochemistry and petrographic analysis of sandstones of the Lower Permian Barakar Formation (Lower Gondwana) Mand valley basin, Chhattisgarh, India have been undertaken to interpret their provenance, tectonic setting, paleoweathering and climatic conditions. The petrology of these Barakar sandstones reveal that they are mainly composed of variable amounts of monocrystalline and polycrystalline quartz, potash and plagioclase feldspars with minor amount of micas and chert as well as metamorphic and sedimentary rock fragments in addition to heavy accessories. Based on the modal analysis, the Barakar sandstones are classified as subarkose and sublitharenite types. Plots of sandstone composition in tectonic setting discrimination diagrams suggest derivation of these detritus from craton interior and recycled orogenic provenance. Tectonic setting discrimination diagrams based on major elements composition suggest a quartzose sedimentary provenance in a passive continental margin. Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alteration (PIA) indices and A-CN-K plot suggest moderate to intense weathering of source rocks under humid climatic condition. Keywords : Barakar Sandstone, Geochemistry, Mand Valley Basin, Provenance, Tectonic Setting.