Late Quaternary glacier advances in the upper catchment area of the Indus River (Ladakh and Western Tibet)

Abstract

Geomorphological mapping in the Markha valley and the northern Nimaling Mountains (Northern Zanskar Range) has revealed eight prominent glacial stages. The two oldest glaciations are marked by glacial abrasion forms as ice-scour limits and glacial benches above the lower and middle Markha valley. These glaciations probably occurred prior to the last glacial cycle. Furthermore, terminal and lateral moraines, glacial tongue basins, basal moraines and tills provide evidence for three glacial stages in the Markha and Nimaling valleys, when the equilibrium-line altitude (ELA) depression was 670–350 m. The glaciations probably occurred during the LGM, the Lateglacial and the Lower Holocene as indicated by the topographic sequence, the ELA depressions and the tentative glacial stratigraphic divisions for the North Indian areas. Large moraine complexes in the vicinity of the present glaciers probably represent three glacial stages of Neoglacial and Historical glacial advances. The ELA depressions are 10–70 m. The present glaciation of the Nimaling Mountains, largely restricted to north flanks and the glacier basins below, covers an area of 45–55 km 2. The modern ELA is calculated at 5650–5750 m a.s.l. on north faces, rising to about 5900–6000 m a.s.l. on south faces. In the central and southern parts of the Ayila Ridge (Western Tibet) present ELAs range from 5700 to 5800 m a.s.l. on the north-facing slopes to 6000–6100 m a.s.l. on southern slopes. Eight former glacier stages are preserved on the southwest flank of these mountains by lateral and terminal moraine ramparts. The ELA depressions amount to 640–950 m.