QUATERNARY GLACIATION OF STOK, NORTHERN ZANSKAR RANGE, TRANSHIMALAYA, NORTHERN INDIA

Determining the extent and timing of present and past glaciation is essential for understanding landscape evolution and paleoenvironmental change in high altitude, active mountain belts such as the Himalayan-Tibetan orogen. The semi-arid western sector of the Himalayan-Tibetan orogen has become one of the most intensely studied regions of this mountain belt. New research has shown that the maximum extent of glaciation and the timing when it occurred has been very different over short distances within this region. This study assesses the glacial record of three tributary valleys (Namlung, Gopal Kangri and Stok Kangri) of the Stok valley, south of the Indus valley in the northern sector of the Zanskar Range in northern India. Geomorphic and ¹⁰Be terrestrial cosmogenic nuclide dating has helped to develop a new robust glacial chronostratigraphy of the Stok valley, to provide the first comprehensive chronostratigraphy of the northern Zanskar Range and to offer insights into the spatial variability of glaciation in the Himalayan-Tibetan orogen. At least four glacial stages are evident within each of the tributary valleys of Gopal Kangri (M_G1-M_G4, youngest to oldest) and Stok Kangri (M_S1-M_S4). With the exception of the M_G4 glacial advance (~124 ka) in the Gopal Kangri valley, the Stok valley as a whole has preserved evidence of glaciations from ~50 ka to the present. ELA and glacier reconstructions for the Stok valley and its tributaries demonstrate that glaciations have become progressively less extensive through time. Former glacier extents of the Stok region are comparable in length with glacial advances during the last glacial cycle in eastern Zanskar and the southern Ladakh Range, to the south and north of the Indus valley respectively. Landscape evolution in the study area has occurred across numerous glacial-interglacial cycles by a combination of glacial and fluvial processes and is similar to that of Ladakh Range.