Geochemistry of Tikak Parbat Sandstones and Tipam Sandstones Occurring in and around Dilli Area, Sivasagar District, Assam, India

摘要

This study presents a geochemical investigation of Tikak Parbat and Tipam Sandstone Formations occurring in and around Dilli area, Sivasagar, Assam. Petrographically Tikak Parbat and Tipam sandstones are mainly quartzose arenite to sublitharenite types with their constituents being derived from recycled orogen provenance under sub-humid to humid climatic conditions. Geochemically, sandstones of both the formations range from sublitharenite to wacke. They indicate a recycled orogen source and influence of humid to arid condition. Source rocks of Tikak Parbat sandstones were more weathered than the Tipam sandstones. While Tikak Parbat sandstones show affinity towards passive margin, Tipam sandstones hint at active continental margin setup, where clasts were supplied from uplifted areas. Upliftment of provenance covering areas of Naga Patkai Range in the south east and Eastern Himalayas along the syntaxial bend during mid Miocene affected the sandstones. Tikak Parbat sandstones reflect a stable tectonic setup which later underwent a phase of volatility leading to deposition of the Tipam sandstones. Our study supports a sediment supply from the upper continental crust, largely of granitic composition, however, with a significant variation in their depth of source supply. Trace element analyses indicate depositional setup with low ventilation marked by both oxic and anoxic phases.