Glacial Geomorphology and Landscape Evolution of the Thangu Valley, North Sikkim Himalaya, India

Abstract

The present study describes glacial-geomorphological landforms in and around Thangu area, North Sikkim, India, and also provides significant insights about the evolution of pro- and paraglacial landscapes. Paraglacial processes are the governing mechanism of landscape evolution in deglaciating valleys and are now studied to understand the deglacial and postglacial landscape dynamics. We here present and describe detailed glacial geomorphology of Lashar and Chopta valleys as the area is strongly modified by the erosional and depositional imprints of late Pleistocene glaciations (MIS 2). Using geomorphological and stratigraphical methods, field surveys, SRTM DEM, Landsat ETM + and Google Earth Pro data, we have mapped glacial and glaciofluvial landforms and established moraine stratigraphy in the study area. Based on the morphostratigraphical mapping of the moraines supported by limited optical chronology, four events of glaciations have been identified in the in the Lashar, Chopta and Kalip valleys and date back to last glacial maximum and advocate for a widespread ice cover with large outlet tributary glaciers. The disposition of the lateral and terminal moraines has been used to estimate the area of paleoglacial extent and their corresponding ice volume during different stages. The presence of proglacial lakes, sensitive indicators of climate change, suggests that the glaciers in the region are melting and radically responding to global warming and are potentially vulnerable for generating glacial lake outburst floods.