Timing and climatic drivers for the MIS 6 glaciation in the central Himalaya: 10Be surface exposure dating of hummocky moraine northwest of Mt. Gang Benchhen, Paiku Gangri

Abstract

Quantifying the timing and extent of Quaternary mountain glaciations can help us in understanding the cause of ice-age cycles. As such, impressive achievements have been made in glacial dynamics across many mountain ranges around the world, such as the Himalayas. Yet, the Marine Isotope Stage 6 (MIS 6) glacial histories have not been well determined across the Himalayan regions due to a lack of adequate chronological controls. Here, we present a 10Be surface-exposure chronology northwest of Mt. Gang Benchhen, Paiku Gangri. Twelve 10Be exposure-ages show that the outermost hummocky moraine outside of the Laqu Valley was formed around ∼165.7 ka, reflecting the MIS 6 glacial maximum in the central Himalaya. The minimum age constraint is consistent with the low atmospheric CO2 levels as well as low summer solar insolation intensity at northern high-latitude, which indicate that glaciers in the Laqu Valley culminated during cold climate condition. Also, we identified a potential correlation between the MIS 6 glacial advance in the central Himalaya and Heinrich-like event. We thus hypothesize that there seems to be a response of Himalayan glaciers to the combined forcing of the boreal summer solar insolation intensities, atmospheric CO2 concentrations, and North Atlantic climate oscillations during the MIS 6 glaciation.