Paleocurrents, Paleohydraulics, and Palaegeography of Miocene-Pliocene Siwalik Foreland Basin of India

Abstract

Early Miocene-Pliocene Middle Siwalik Subgroup of Kuluchaur area, Uttarakhand, North India, comprises sheet-like, coarse to medium grained, cross bedded sandstone bodies and multistoreyed variegated mudstones. Paleocurrent study shows commonly unimodal and locally bimodal distribution and displays a high magnitude of resultant (R*=0.7337) oriented towards south-southwest (206° ± 42.27°). Palaeochannel morphological attributes suggest that the depositing river system was about 230 m wide and 4.5 m deep. These broad, shallow, and low sinuous channels with extensive flood plain flowed on a steeper slope (0.00043 degrees) with flow velocity of 60–140 cm/sec. It is visualized that the immature Middle Siwalik rocks were deposited by southward flowing braided rivers transverse to the Himalayas, predominantly in the form of overlapping alluvial fans similar to those depositing sediments at present in the Indo-Gangetic plains. Fairly consistent fluvial palaeoslopes, together with enormous thickness of sediments, are evidences of rapid subsidence of the basin. We conclude that the paleogeography of Indian subcontinent established at the onset of Miocene-Pliocene Siwalik sedimentation is continuing till today.

Revisiting the diachronous transition of C3 to C4 plants in the Himalayan foreland and other parts of the globe: A sedimentological perspective

“…Irrespective of the slope, the sinuosity of the Siwalik channels is similar to the modern fan rivers and fall mostly in the zone of braided rivers (sinuosity <1.26; Schumm, 1985). This observation is in good agreement with the slope (calculated from the available set thickness, Table S2) and sinuosity data from the other Siwalik regions of the Himalayan foreland basin (HFB) (Shukla et al, 2009;Mandal et al, 2014;Goswami & Deopa, 2014;Khan & Tewari, 2015). The comparison of slope and sinuosity data with the modern fan rivers and sedimentological analysis together suggest that the Siwalik Group at the Kangra sub-basin (KSB) were possibly deposited either in a small fan or at the proximal part of a medium or large fan (Fig.…”

“…The filled and empty stars represent the slope S 1 (Schumm, 1972) and S 2 (Trampush et al, 2014), respectively. The average slope and sinuosity of the other Siwalik regions (estimated following Schumm, 1972;black dots;Khan & Tewari, 2015;Shukla et al, 2009;Goswami & Deopa, 2015;Mandal et al, 2014) are also comparable with the KSB data. The error bar indicates the uncertainty associated with the estimation of slope (S 1 ) of the Siwalik channels.…”

Analyzing Sedimentary Rocks to Evaluate Paleo Dimensions and Flow Dynamics of Permian Barakar River of Rajmahal Gondwana Sub-Basin of Eastern India

“…Additional approximation of the paleoslope can be derived using the Manning equation for the open channel flow systems. This same relationship has been used to determine the paleochannel slope in many ancient fluvial rivers [5,8].…”

“…Recent researches provide a methodology to evaluate paleo dimensions and flow dynamics of ancient fluvial systems [5][6][7]. Fluvial paleo-channels can be scaled from numerical equations based on grain size along with channel depth and width measurements and augmented by flow depth estimated from estimated dune bed form height from cross bedding set thickness using data of cross bedding set thickness [2,3,8]. Calculated parameters include mean bed form height, channel depth, channel belt width, channel width, paleoslope, boundary shear stress; Darcy-Weisbach friction factor, paleoflow velocity, and paleo discharge provide insight into basin analysis.…”