Reconstructing the Pattern of Late Quaternary Climate Through Sediment-Landform Assemblages in the Dhauli Ganga Valley (upper Ganga Catchment), India

The present study focuses on the reconstruction of the pattern of late Quaternary climate variability through sediment-landform assemblages in the monsoon-dominated Dhauli Ganga valley. The South Tibet Detachment System (STDS) is a major litho-tectonic boundary that divides the Dhauli Ganga valley into two broad geomorphic entities. Towards the north of STDS, the valley is wide and “U” shaped, and the rivers have a braid-meandering channel, implying that the valley was carved by glacial sculpturing in the past. Whereas in the south, deep gorges indicate the dominance of fluvial processes. Based on the stratigraphic position and optical chronologies, the lithified moraines were assigned to Marine Isotopic Stage-3 (MIS-3) they were followed by a major deglaciation event represented by moderately lithified outwash gravels. Following this, a second glacier advance of lesser magnitude is dated 21.3 ± 2.2 ka, corresponding to the Last Glacial Maximum (LGM). A gradual recession of the LGM moraines led to the formation of a proglacial lake which probably persisted until around the onset of a pulsating deglaciation stage represented by outwash gravels dated between 13.4 ± 1.6 and 9.4 ± 0.8 ka. This was also the period when the valleys were overwhelmed by a high sediment water ratio, as indicated by temporary impoundments dated between 15.0 ± 1 ka and 10.0 ± 1 ka. Alluvial fan and debris flow sedimentation overwhelm the valley after around 9 ka and continues till the present.