The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau(QTP) is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides(TCN) 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap(pDIC), southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B?lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.
ZHANG ZhigangXU XiaobinWANG JianZHAO ZhijunBAI ShibiaoCHANG Zhi Yang
The glacial landforms of the Qinghai-Tibetan Plateau(QTP) provide a unique opportunity to research hemispheric and global environmental changes. In this study,we focus on the glacial history of the palaeo-Daocheng Ice Cap(p-DIC) in the southeastern QTP during the last glacial cycle. Based on field investigations,morphostratigraphy,and surface exposure dating of roche moutonnée,polished surface and moraine debris through the terrestrial cosmogenic nuclides(TCN) 10 Be and 26 Al. We identify glacial deposits of the last deglaciation,with minimum ages of 14.9±1.3–18.7±1.7 ka,the Last Glacial Maximum(LGM) of 24.7±2.2 ka,and the early part of the last glacial period(marine oxygen isotope stage(MIS) 3) of 37.1±3.4–45.2±3.9 ka. Our results show that in this region,the extent of the glacial advance during MIS 3 was larger than that during the traditional LGM(MIS 2). These ages are consistent with prior chronologies,and the 10 Be age is consistent with the 26 Al age for the same sample. Thus,these data provide reliable constraints on climate change in the QTP,during the last glaciation.
