Provenance of the Middle Siwalik sandstones of the Himalayan foreland basin (south central Kumaun, India): Implications for tectonics and paleoclimate of the source area

Abstract

Thirty medium-to fine-grained sandstone samples of the Middle Siwalik Subgroup of the south central Kumaun Himalaya have been subjected to detailed petrographic and petrofacies analyses. The sandstones are moderately to well-sorted, lithic and sublithic arenites. They are quartzolithic, having abundance of metasedimentary and sedimentary lithic fragments, which characteristically derive from a recycled, collision orogen provenance of quartzose and mixed quartzose-lithic terrains. The primary and accessory framework grains of the sandstones are of mixed igneous, sedimentary, and low-to high-grade metamorphic affinity. The petrographic and petrofacies characters suggest derivation of the sandstones from a vast area extending across the nearby located Lesser and Great Himalayan terrains. A comparison of these sandstones' QtFL petrofacies and petrographic characters with the similar data from Middle Siwalik sandstones of other studied sections reveals that their compositions are comparable all across the entire expanse from Potwar Plateau in Pakistan to eastern Himalaya in India; the Middle Siwalik sandstones everywhere have been sourced from the Lesser and Great Himalayan terrains, albeit with varying proportions through space and time.

Mio‐Pliocene exhumation of the hinterland and sediments provenance of the Neogene strata from Kumaun Himalaya of northwest India: Insights from detrital fission‐track thermochronology

“…The Kumaun-Garhwal region is comprised of four distinct tectonic zones from north to south, such as the THS, HHC, LHMS and the sub- Himalaya (Figure 2a, b;. The HHC extruded between the Main Central Thrust (MCT) in the south and the South Tibetan Detachment System (STDS) in the north and emplaced southward over the LHMS during 23-17 Ma (Searle et al, 1997;Walker et al, 1999;Godin et al, 2006;Mukherjee, 2013;Mukherjee & Koyi, 2010a, 2010bBose & Mukherjee, 2019, 2020Ghosh & Mukherjee, 2021;Singh et al, 2020;Singh et al, 2021, Singh, Sethy, Rastogi, et al, 2023. The HHC zone has two distinct lithotectonic units: an upper unit named the Vaikrita Group and a lower unit named the Munsiari Formation (Figure 2a; Valdiya, 1980;Patel & Kumar, 2006;Patel & Carter, 2009;Singh, 2014;Singh et al, 2012;Singh, Sethy, Rastogi, et al, 2023;.…”

“…The lower Siwalik rock is characterized by the finest grain of all the lithofacies with the dominance of purple-brownish-dark grey coloured, compact mudstones interbedded with siltstones and pepper textured, medium to coarse-grained brownish sandstones (see Figure 2c). The ripple marks indicate either upward fining or coarsening in sandstones (Goswami, 2020;Kotlia et al, 2001). Near Kathgodam town, the dominance of flood-flow deposits is represented by the fine-grained fluvial systems and mainly characterized by sandstone and mudstone.…”