Late Holocene Glacier Dynamics in the Miyar Basin, Lahaul Himalaya, India

Sanjay Deswal,Ajai Ajai,Milap Sharma,Ishwar Singh,Pritam Chand,Navin Juyal,Rakesh Saini,I.M Bahuguna,Pradeep Srivastava

doi:10.3390/geosciences7030064

Abstract

Detailed field mapping of glacial and paraglacial landforms and optical dating from these landforms are used to reconstruct the early Holocene glaciation in the semi-arid region of Miyar basin, Lahaul Himalaya. The study identifies three stages of glaciation, of decreasing magnitude and termed, from oldest to youngest, the Miyar stage (MR-I), Khanjar stage (KH-II), and Menthosa advance (M-III). The oldest glacial stage (MR-I) has been established on the basis of detailed geomorphological evidence such as U-shaped valley morphology, trimlines, and truncated spurs. It is speculated to be older than the global Last Glacial Maximum (gLGM) based on the magnitude of ΔELA (Equilibrium-Line Altitude, 606m). No evidence of glacier expansion recorded from the basin correlates with the period of the gLGM. The second stage (KH-II) is well represented by extensive depositional features such as lateral and terminal moraines, drumlins, and lacustrine fills that have been constrained within 10 ± 1 to 6.6 ± 1.0 ka (Optically stimulated luminescence—OSL—ages), dating it to the early Holocene advance following the Younger Dryas cooling event. Exceptionally young glacial records of expansion are limited within a few hundred meters of the present termini of tributary glaciers and correlates with the 18th-century cooling event. Records of this glacial advance, termed the Menthosa advance, are clearly noticed in some tributary valleys.

Highlights

The Himalayan-Tibetan (H-T) orogeny altered large-scale climate systems including the Asian monsoon and considerably influenced the regional and global atmospheric circulation that may have played a key role in the onset of Quaternary glaciation [1,2,3,4,5,6]
These have been named, from oldest to youngest, the Miyar stage (MR-I), Khanjar stage (KH-II), and Menthosa event of glaciation are discerned in the basin and discussed below
The oldest Miyar stage (MR-I) is assigned to pre-global Last Glacial Maximum (gLGM) times based on geomorphological evidence

Summary

Introduction

The Himalayan-Tibetan (H-T) orogeny altered large-scale climate systems including the Asian monsoon and considerably influenced the regional and global atmospheric circulation that may have played a key role in the onset of Quaternary glaciation [1,2,3,4,5,6]. Information on the geographic extent and magnitude of Quaternary glaciations in this largest glacierized area outside the polar region is important for understanding the climatic and tectonic evolution of this giant orogenic system [7,8,9,10]. The growing availability of chronological data in recent years has emerged, yet there is no general consensus concerning the timing, extent, and climatic forcing of glaciations in the Himalayan region [12,15,16].

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Discussion

Conclusion