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 quartz...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.展开更多
Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Pr...Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Prakash & Tripathi, Bombacacioxylon tertiarum Mehrotra et al., gen. et sp. nov., Dipterocarpoxylon jammuense Guleria et al. and Bischofia palaeojavanica Awasthi are described from there. They resemble the modern taxa, namely Swintonia Griff.(Anacardiaceae), Dipterocarpus C.F. Gaertn.(Dipterocarpaceae), Bischofia Blume(Euphorbiaceae) and the taxa of the family Bombacaceae. The distribution of the modern equivalents of the present and previously described taxa indicates the existence of warm and humid climate in Mizoram during the depositional time.展开更多
文摘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.
文摘Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Prakash & Tripathi, Bombacacioxylon tertiarum Mehrotra et al., gen. et sp. nov., Dipterocarpoxylon jammuense Guleria et al. and Bischofia palaeojavanica Awasthi are described from there. They resemble the modern taxa, namely Swintonia Griff.(Anacardiaceae), Dipterocarpus C.F. Gaertn.(Dipterocarpaceae), Bischofia Blume(Euphorbiaceae) and the taxa of the family Bombacaceae. The distribution of the modern equivalents of the present and previously described taxa indicates the existence of warm and humid climate in Mizoram during the depositional time.
