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Elemental concentrations of the siliciclastic sediments from a sedimentary basin provide clues on paleoweathering, paleoclimate, provenance, and tectonic setting of the basin. Records for Permo–Triassic mass extinction and climatic fluctuations are commonly traced from the sediments in the Gondwana basins. Nevertheless, our understanding on sedimentation, provenance, and regional tectonics of the Raniganj Basin, a Gondwana basin in the eastern India is poor. Minerals including clay particles and major and trace element concentrations of the siliciclastic sediments from different formations of the Raniganj Basin have been studied to establish the paleo-weathering, paleoclimate, provenance, and tectonic settings of the basin. This study suggests that the Talchir Formation experienced cold and dry climatic conditions at the sediment source area, while the Barakar, Raniganj, and Panchet formations had prevailing semiarid climates. The sources of the siliciclastic sediments are from the felsic rocks of the Chotanagpur Granite Gneissic Complex (CGGC). Further, the geochemical results suggest a rift-like (passive) tectonic setting for the Raniganj Basin, while few samples represent the collision tectonic setting of the basement CGGC, formed due to collision of major Indian blocks during the Paleo-Neoproterozoic time.
| 1. | The weathering and paleoclimatic studies of the studied samples suggests that in the Raniganj Basin, the Talchir Formation indicates low chemical weathering during cold/temperate climates, whilst that of the Barakar, Raniganj, and Panchet formations shows moderate weathering of semi-arid climatic conditions. |
| 2. | The trace element concentrations of studied sediment samples from the Raniganj Basin, such as REE patterns, elemental ratios like La/Sc, Cr/Th, and Co/Th, and discrimination plots such as Hf vs. La/Th, Sc vs. Th/Sc, and La/Sc–Sc/Th diagrams, suggest that the provenance of the sediments might be from the CGGC which consists of porphyritic granitoid and charnockites with enclaves of mafic granulites, khondalites, calc-silicates, and minor quartzite. |
| 3. | The two tectonic setting discriminant diagrams based on major elements and low Th/Sc values in the studied siliciclastic sediments suggest a rift origin (passive) tectonic setting for the Raniganj Basin. The diagrams also indicate that some sediment samples of the Raniganj Basin are associated with collision tectonic settings. The affinity of the collision tectonic setting in some samples of the Panchet and Raniganj formations may be due to the basement CGGC source signature, formed by the collision of major Indian blocks, during Paleo-Neoproterozoic time. |
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |