Paleoglacial and paleoclimate reconstructions during the global Last Glacial Maximum in the Longriba area, eastern Tibetan Plateau

Owing to the remoteness of the Longriba area and the lack of dating records, it is extremely challenging to reconstruct the chronology and extent of the paleoglaciers in this area. In this paper, we combined limited observational data with automated modelling for paleoglacial reconstructions. We first identified a broadly distributed paleoglacier from satellite imagery and field investigation based on the sediment-landform assemblage principle and dated it to 23.1±1.4~19.5±1.2 ka by ¹⁰Be exposure dating, corresponding to the global Last Glacial Maximum (gLGM). Then, we reconstructed the extent and ice surface of 171 paleoglaciers formed during the similar period based on geomorphological evidence and 'ice surface profile' modelling. The results showed that the paleoglacial coverage was 426.5 km², with an ice volume of 38.1 km³, in the Longriba area. The reconstructed equilibrium line altitudes (ELAs) based on modelled ice surfaces yielded an average of 4245±66 m above sea level (asl), ~725±73 m lower than the present ELA (4970±29 m asl). The temperature was ~5.51-6.68 ℃ lower, and the precipitation was ~30-34% less in Longriba, during the gLGM compared to the present day. This glacial advance was mainly driven by colder climate that was synchronous with Northern Hemisphere cooling events.