Late-glacial fluctuations of Himalayan glaciers: 10Be surface exposure dating northwest of Mt. Gang Benchhen

Abstract

Robustly-dated glacial landforms provide us a means of examining millennial-scale climate events during the late-glacial period, which could shed new light on the bipolar seesaw hypothesis. Although many moraines are proposed to be late-glacial in age across the Himalayas, the well-determined late-glacial moraine sequences remain extremely rare in the central Himalaya (e.g. the Paiku Gangri area). The paucity of high-precision chronologies limits our ability to fully explore the response of Himalayan glaciers to late-glacial climate reversals. Here, we present a detailed geomorphic map of glaciers in the Laqu River Valley, northwest of Mt. Gang Benchhen and a10Be-based moraine chronology from 24 boulders from the late-glacial period. The dating results indicate that glaciers in the studied catchment reached their maximum late-glacial extent about 16.1 ka ago, prior to the Younger Dryas Stadial (YDS), and that a following glacial culmination occurred at 12.2 ± 0.9 ka, corresponding roughly to the YDS. The emerging pattern of glacial fluctuations is similar at local, regional, and global scales, suggesting a interhemispheric coherency of late-glacial glacier behaviors. The Analysis of dynamic response of Himalayan glaciers to climate change suggests a temperature-sensitive mountain-glacier system, supporting the view that the bipolar seesaw was primarily a northern winter phenomenon during the late-glacial interval.