Late Pleistocene glacial advances in the western Tibet interior

Abstract

It has long been observed that the timing of glacial advances is asynchronous across the Himalaya–Karakoram–Tibet Plateau (HKTP) but the climatic implications, if any, remain unclear. Resolving this question requires additional glacial chronologies from unique spatial and climatic regimes as well as an analysis of how glaciers within different regimes are likely to have responded to past climate changes. This study presents a ^(10)Be–^(21)Ne chronology from the Mawang Kangri range of western Tibet (∼34°N, 80°E); an arid high-elevation site. We identify advances at ∼123, 83, and 56 kyr, which agree reasonably well with sites in the immediate vicinity, but are asynchronous relative to sites across the entire HKTP, and relative to sites in the western HKTP. To evaluate HKTP-wide asynchroneity, we compile dated glacial chronologies and classify them by the approximate timing of their maximum recent advance. This result shows a strong spatial clustering of young (MIS 1–2) relative to older (MIS 3–5) maximum advances. Further comparison with modern precipitation, temperature, and topographic data show that the pattern of HKTP-wide asynchroneity is broadly independent of topography and can potentially be explained by local responses to changes in temperature at either very warm-wet or cold-dry sites. Sites that receive intermediate amounts of precipitation are more ambiguous, although spatial clustering of MIS 1–2 vs. MIS 3–5 advances is suggestive of past variations in precipitation at these sites. In western Tibet, no spatial or climatic correlation is observed with the timing of maximum glacial advances. We suggest this could arise from mis-interpretation of disparate boulder ages generated by a prolonged MIS-3/4 glacial advance in the western HKTP.