Sedimentary characteristics of palaeolake deposits along the Indus River valley, Ladakh, Trans‐Himalaya: Implications for the depositional environment

Abstract

This study is an attempt to contribute to the data set of granulometric studies of sediments by measuring the sedimentary structure and texture, along with statistical parameters, of cold and arid lake systems. The palaeolake sequence along the River Indus on the western fringe of the Tibetan Plateau in Ladakh sector was selected in order to shed light on depositional environmental changes within the lake from post-last glacial maximum to 5 ka. The River Indus was blocked by Lamayuru dam burst during the deglaciation, after the Last Glacial Maximum (LGM) and the subsequent increase in water level led to the formation of the Saspol-Khalsi palaeolake. This lake was ca 55 km in length, extending from Nimo to Khalsi, had a surface area of 370 km 2 and was in existence until 5 ka. Two sections (Saspol and Khalsi) separated by an aerial distance of 35 km show a similar trend in sediment character due to their deposition in the same lake system. Grain-size studies show a polymodal nature of sediments for both of the sections. However, sediments of the lower/downstream section (Khalsi) show a poorer degree of sorting, and coarser grain size and high energy depositional condition as compared with the sediments of Saspol section (positioned upstream) due to the location of the sections within the lake system. It was noted that, in high-altitude arid regions, the sedimentological characteristics of large-sized valley lakes may vary greatly, horizontally as well as vertically, owing to local stream input, inflow intensity from the catchment, outflow velocity of water channels, lithology and valley widths at the different sites.

Late Quaternary Palaeoclimate and Contemporary Moisture Source to Extreme NW India: A Review on Present Understanding and Future Perspectives

“…In our research endeavors in the Ladakh and Spiti regions of NW India, primarily dedicated to the Quaternary geomorphology and fluvio-lacustrine deposits, we have carried out extensive field reconnaissance surveys supported with laboratory-based dataset, and discussed the landscape evolution and paleoclimate of the region in our publications (Phartiyal et al, 2005(Phartiyal et al, , 2009a(Phartiyal et al, ,b, 2005(Phartiyal et al, , 2013(Phartiyal et al, , 2015Phartiyal and Sharma, 2009;Srivastava et al, 2013;Nag et al, 2016) and still continuing with it. A cursory look of the geomorphological signatures present in the entire NW Himalayan region (Figures 1-3) indicates that the region has experienced glacial advance (glacial phase) and retreat (interglacial phase) at different time intervals.…”

The role of climate and tectonics in aggradation and incision of the Indus River in the Ladakh Himalaya during the late Quaternary

“…This suggests that the ~35 m Spituk lake sequence took >100 ka to aggrade; implying an average sedimentation rate of 0.35 mm/yr, which is not realistic. The varve and sedimentary rythmites in the Spituk sequence that are supposed to be annual sedimentary layers are less than a centimeter in thickness indicating a much higher sedimentation rate (3–4 mm/yr; Nag et al, 2016). The chronological data published from the paleolake sequences from across the Himalaya also seem to suggest much higher sedimentation rates (Fort, 2000; Korup et al, 2006; Phartiyal et al, 2009; Anoop et al, 2013; Srivastava et al, 2013; Nag and Phartiya, 2015).…”

Late Quaternary sedimentation history of the Himalaya and its foreland

“…The valley-fill sequences along the Tangste River (Trans-Himalaya) show two phases of aggradation at 48 and 30-21 ka (Phartiyal et al, 2015). Further, a study establishing the chronology of the paleolake deposits along the Indus River suggested three phases of lake formation during warm and wet climate at ~35-26 ka (Lamayuru palaeolake); 17-13 ka (Rizong palaeolake), and 14-5 ka (Khalsi-Saspol palaeolake) (Nag and Phartiyal, 2015;Nag et al, 2016). Episodic filling in the valley was caused by glaciogenic, fluvial, lacustrine, and alluvial sedimentation during intensified monsoon periods (Phartiyal et al, 2015).…”