A 10Be Moraine Chronology of the Last Glaciation and Termination at 49°N in the Mongolian Altai of Central Asia

Determining what caused the global Last Glaciation and last glacial termination, despite opposing orbital summer insolation signatures between the polar hemispheres, remains a puzzle of paleoclimatology. This problem can be addressed by comparing chronologies of glaciation from different latitudes and different climatic regimes in both hemispheres. Here, we present a Be-10 surface-exposure chronology of glacial landforms constructed during and since the local Last Glaciation in the continental environment of Central Asia in the high Mongolian Altai (49 degrees N, 88 degrees E). Four belts of lateral moraines document maximal phases of the former Khoton glacier at 35,440 +/- 980 years ago, 23,430 +/- 850 years ago, 20,780 +/- 610 years ago, and 19,520 +/- 550 years ago. Our chronology indicates that deglaciation from these maximal positions began as early as 18,810 +/- 510 years ago, was well underway by 17,680 +/- 510 years ago, and was nearly completed by 16,040 +/- 490 years ago. Overall, our chronology shows that glaciation in western Mongolia overlapped with the global Last Glacial Maximum and that extensive recession from glacial-to-interglacial limits took place early in the last glacial termination during Heinrich Stadial 1. Khoton Nuur deglaciation led the demise of large Northern Hemisphere ice sheets and increases in radiative forcing agents by several millennia. We suggest that this rapid switch in the mode of glaciation implies the involvement of an additional climatic factor that could have produced locally rapid warming and deglaciation similar to 18,800-16,000 years ago.

Automated summary

The study examines the glaciation period in Central Asia, particularly the Mongolian Altai region, and finds that the glaciers reached their maximum phases around 35,440 years ago. Deglaciation began as early as 18,810 years ago and was mostly completed by 16,040 years ago. This research suggests that an additional climatic factor may have played a role in the rapid deglaciation around 18,800-16,000 years ago.