Rapid Last Glacial Maximum deglaciation in the Indian Himalaya coeval with midlatitude glaciers: New insights from ¹⁰Be‐dating of ice‐polished bedrock surfaces in the Chandra Valley, NW Himalaya

Abstract

Despite a large number of dated glacial landforms in the Himalaya, the ice extent during the global Last Glacial Maximum (LGM) from 19 to 23 ka is only known to first order. New cosmogenic 10Be exposure ages from well‐preserved glacially polished surfaces, combined with published data, and an improved production rate scaling model allow reconstruction of the LGM ice extent and subsequent deglaciation in the Chandra Valley of NW India. We show that a >1000 m thick valley glacier retreated >150 km within a few thousand years after the onset of LGM deglaciation. By comparing the recession of the Chandra Valley Glacier and other Himalayan glaciers with those of Northern and Southern Hemisphere glaciers, we demonstrate that post‐LGM deglaciation was similar and nearly finished prior to the Bølling/Allerød interstadial. Our study supports the view that many Himalayan glaciers advanced during the LGM, likely in response to global variations in temperature.

Studies on Quaternary Glaciations in India During 2010-2016

“…In addition, they also reported glacial advances during ~17-15 and ~79-52 ka in the middle Yunam valley. Another recent study based on cosmogenic 10 Be exposure ages from well-preserved glacially polished surfaces, combined with published data, and an improved production rate scaling model allow reconstruction of the LGM ice extent and subsequent deglaciation in the Chandra valley of NW India (Eugster et al, 2016). They support the view that many Himalayan glaciers advanced during the LGM, likely in response to global variations in temperature.…”

“…In the Himalaya, previous studies suggested strong sensitivity of glaciers to variations in precipitation gradient from eastern Himalaya to the Karakoram ranges in the west and thus to orbitally driven monsoon intensity Eugster et al 2016). In the central and eastern Himalaya, it has been suggested that glaciers expanded predominantly during strengthened phases of the ISM with minor advances during weak phases of the ISM (Owen 2009;Dortch et al, 2010b;Owen and Dortch 2014;Sati et al, 2014).…”

“…In the central and eastern Himalaya, it has been suggested that glaciers expanded predominantly during strengthened phases of the ISM with minor advances during weak phases of the ISM (Owen 2009;Dortch et al, 2010b;Owen and Dortch 2014;Sati et al, 2014). While in the western Himalaya westerlies seem to dominate the post LGM glaciations (Dortch et al, 2013;Eugster et al, 2016). Owen et al (2005) proposed that the glaciers in humid areas advanced due to changes in precipitation, whereas, glaciers in more arid areas are temperature driven and advanced synchronously with northern hemisphere ice sheets.…”

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

“…In contrast to older studies, more recent studies on glacial chronology from the Lahaul region have suggested considerable glacial expansion at the time of the global LGM [76,90]. However, signatures of glacial episodes between MR-I and KH-II are completely missing in the Miyar basin, and the MR-I stage might be related to the Chandra stage proposed earlier in the region given the magnitude of glacier expansion [24,70].…”

“…The samples were stimulated using blue (470 ± 20 nm) light emitting diodes (LED), and detection optics comprises a bi-alkali type photomultiplier tube (PMT) (EMI 9835QA) coupled with a 7.5mm Hoya U-340 filter (emission 330 ± 35 nm). Beta irradiations were carried out using an on-plate 90 Sr/ 90 Y beta source with a dose rate of 5.49 gy/ka. The elemental concentrations of uranium, thorium, and potassium for environmental dose rate estimation were carried out using the high-purity Germanium detector.…”