TIMING AND EXTENT OF LATE QUATERNARY GLACIATIONS IN THE COGARBU VALLEY, EASTERN HIMALAYA ALONG THE CHINA-BHUTAN BORDER, INVESTIGATED USING 10BE SURFACE EXPOSURE DATING

The section of the Himalayas along the China-Bhutan border is one of the intensively glaciated centers with well-preserved moraines and glacial deposits. These landforms and deposits provide a useful record in reconstructing the high-resolution histories of the Indian summer monsoon, Quaternary glaciation, and environmental evolution on the southern Tibetan Plateau. We investigated the late Quaternary glacial landforms and deposits in the Cogarbu Valley on the northern slopes of the mountain range based on glacial geomorphological mapping and ¹⁰Be surface exposure dating. Twenty-eight ¹⁰Be exposure ages from seven moraines produced ages of 0.45 ± 0.05 ka, 1.0 ± 0.1 ka, 10.6 ± 1.1 ka, 15.6 ± 1.5 ka, 21.1 ± 2.1 ka, 22.7 ± 2.1 ka, and 23.6 ± 2.2 ka, respectively. These exposure ages suggest five major glacial events during the Little Ice Age (LIA), Neoglacial, the early Holocene, Lateglacial, and the global Last Glacial Maximum (LGM). These events were broadly synchronous with other areas in the Monsoon Himalayas. Multiple moraines are dated to the LGM, suggesting glaciers fluctuated frequently during this period in response to short-term variations in temperature or precipitation. The high-resolution glacial chrono-stratigraphy provides important insight into the interlinkages between climatic, tectonic and glacial systems.