Shallow marine to fluvial transition in the Siwalik succession of the Kameng River section, Arunachal Himalaya and its implication for foreland basin evolution

Abstract

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Biomarker and Carbon Isotopic Evidence of Marine Incursions in the Himalayan Foreland Basin During Its Overfilled Stage

“…Similar paleo-depositional conditions are also observed from other time-equivalent eastern HFB deposits, where thick deltaic deposits from brackish water suggest deposition under shallow marine conditions (Figure S9) (Chakraborty et al, 2020;Chirouze et al, 2012;Coutand et al, 2016;Taral et al, 2019). The random occurrence of marine invertebrate, palynological and ichnogenera assemblages in the eastern foreland deposits possibly suggest episodic marine influences within a persistent fluvial-dominated environment.…”

“…Several syn-sedimentary faults and soft-deformational structures reported from the eastern foreland sedimentary successions provide evidence of thrust movement from paleo-seismic events (Kundu et al, 2011), which might have allowed marine incursions into the eastern HFB. These smaller marine incursions were traced in the foreland sediments using specific biomarkers (in this study) and occasionally by field-based paleocurrent analysis (Chakraborty et al, 2020;Taral et al, 2017Taral et al, , 2019. The marine incursions are hypothesized to have formed hypersaline brackish water conditions within the prevailing braided river systems, thereby allowing the preservation of frequent woodblocks (Coutand et al, 2016).…”

“…The preliminary sedimentological investigations provided contradictory evidence of both terrestrial and marine paleo‐depositional conditions in the eastern part of HFB (Banerjee & Banerjee, 1982; Coutand et al., 2016; Kundu et al., 2011, 2012, 2016; Mandal et al., 2014; Taral & Chakraborty, 2018; Taral et al., 2017, 2019). Pollen and leaf‐macrofossils have been widely used to suggest an exclusive terrestrial environment, although rare and punctuated occurrences of mangrove taxa have indicated coastal settings (Coutand et al., 2016; Joshi et al., 2003; Khan et al, 2016, 2019, 2016; More et al, 2016, 2018; Paruya, 2012).…”

“…The paleo‐depositional interpretation from the invertebrate fossils was further challenged due to their limited occurrence and the possibility of its derivation from the older Himalayan tertiary rocks (Acharyya et al., 1987). Recently, efforts have been made to reconstruct the past environmental conditions using ichnofossils (Chakraborty et al., 2013; More et al., 2018; Taral et al., 2018, 2019; Ulak, 2009). Specific ichnogenera traces in pre‐requisite amounts are considered as important paleo‐environmental markers (MacEachern et al., 2008).…”

Sedimentary Facies Analysis of the Fluvial Environment in the Siwalik Group of Eastern Nepal: Deciphering its Relation to Contemporary Himalayan Tectonics, Climate and Sea-Level Change.

“…Moreover, uvial behaviour is governed not only by the interplay between tectonics and climate but also by sea-level change (Burbank et al, 1992;Goodbred and Kuehl, 2000a;2000b). In the Siwalik Group along the Darjeeling-Sikkim and Arunachal Pradesh evidence of sediment deposited in deltaic and open Marine depositional settings is reported (Taral et al, 2018;2019). The present study area lies in the eastern part of the Nepal Himalaya near to the Darjeeling-Sikkim section.…”