Depositional character of a dry-climate alluvial fan system from Palaeoproterozoic rift setting using facies architecture and palaeohydraulics: Example from the Par Formation,Gwalior Group,central India |
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| Institution: | 1. Research Institute of Petroleum Industry (RIPI), Tehran, Iran;2. IOR/EOR Institute for Oil and Gas Reservoirs, National Iranian Oil Company, Tehran, Iran;3. National Iranian Oil Company, Exploration Directorate, Tehran, Iran;1. Department of Geological Sciences, Jadavpur University, Kolkata 700032, India;2. Department of Earth Sciences, IIT Bombay, Powai, Mumbai 4000076, India;3. Department of Geology, Durgapur Government College, Durgapur 713214, India;4. Department of Geology, Delhi University, Delhi 110007, India;1. Atomic Minerals Directorate for Exploration and Research, 1-10-153-156, S.P. Road, Begumpet, Hyderabad 500 016, India;2. Department of Applied Geochemistry, Osmania University, Hyderabad 500 007, India;1. Petróleo Brasileiro SA, PETROBRAS. Av. República do Chile 330, 9° andar, Torre Leste, Zip code: 20031-170, Rio de Janeiro, RJ, Brazil;2. Universidade Federal do Rio Grande do Sul, UFRGS. Av. Bento Gonçalves 9500, Prédio 43137, Agronomia, Zip code: 91501-970, Porto Alegre, RS, Brazil;3. University of Alberta, 8029-112 Street, Edmonton, Alberta T6G 1K2, Canada;1. Department of Petrology and Economic Geology, GEUS – Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 København K, Denmark;2. CEMPEG, Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden;3. Faculty of Geology, Geophysics and Environmental Protection, AGH – University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, Poland |
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| Abstract: | The ∼20 m thick coarse-grained clastic succession in the basal part of Palaeoproterozoic Par Formation, Gwalior Group has been investigated using process-based sedimentology and deductive palaeohydraulics. Bounded between granitic basement at its base and shallow marine succession at the top, the studied stratigraphic interval represents products of an alluvial fan and its strike-wise co-existent braided river system that possibly acted as a tributary for the fan. Detailed facies, facies association analysis allowed identification of two anatomical parts for the fan system viz. proximal and mid fan. While thin proximal fan is represented by products of rock avalanche and hyperconcentrated flows with widely varying rheology, the mid fan is represented by products of sheet floods and flows within streamlets. The interpretation found support from palaeoslope estimation carried out on the fluvial part of the mid fan that plot dominantly within the alluvial fan field demarcated by Blair and McPherson (1994). Dry climatic condition suggested from dominance of stream flow over mass flow deposition within the Par alluvial fan. Strike-wise, the fan is discontinuous and juxtaposed with a braid plain system. In contrast to the fluvial part of fan system, the palaeoslope data from the braid plain system dominantly plot within the ‘natural depositional gap’ defined by Blair and McPherson. A raised palaeoslope for the river systems, as suggested from Proterozoic braid plain deposits around the Globe, is found valid for the Par braid plain system as well. From preponderance of granular and sandy sediments within the alluvial fan and braid plain systems and a pervasive north-westward palaeocurrent pattern within the fluvial systems the present study infers a gently sloping bevelled source area in the south-southeast of the basin with occurrence of steep cliffs only locally. |
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| Keywords: | Palaeoproterozoic Gwalior Alluvial fan Fluvial Palaeoslope Palaeohydraulics |
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