Research advances of the ice sheet history in the Larsemann Hills and adjacent regions,East Antarctica
The evolution of the East Antarctic Ice Sheet can significantly affect global climate change since de-glaciation could contribute much to sea-level dynamics. Thus,studying ice sheet history in this region is the key to understanding the Quaternary global and regional climate change. In recent years,in-situ Terrestrial Cosmic Nuclides (TCN) exposure dating has been gradually applied to the dating of glacial dynamics in the Larsemann Hills area. The data of Quaternary glacial chronology in this area can be employed further to understand the chang-es in the Antarctic Ice Sheet,and the dating results from this method currently require further refinement. This study summarized and homogenized 19610Be exposure dating data from 1997 to 2022 of the Larsemann Hills and adjacent areas. These areas include the Larsemann Hills,Vestfold Hills and Rauer Group,Prince Charles Moun-tains,and Grove Mountains. The sampling information such as sample type,altitude,latitude,elevation,shield-ing factors,thickness,erosion rate,density,and AMS results were also counted. Based on distinguishing erratic and bedrock samples,we applied the newest model to all of the sample data and recalculated them. Meanwhile,the onset of biogenic sedimentation in the Larsemann Hills has been recorded with bedrock exposure data for further discussion. The results showed that the minimum exposure age of the Larsemann Hills was (4.05±0.81) ka,and the maximum exposure age was (147.01±11.80) ka. The minimum age of exposure in its adjacent areas ranged from (0.32±0.20) ka to (4096±2404) ka. The earliest date reaches the mid-Pleistocene,specifically MIS Gi24,spanning the entire Quaternary period. Among all the samples discussed,17.86％ have an exposure age of less than 11 ka,83.16％ have an exposure age of less than 600 ka,and 98.47％ have an exposure age of less than 2.8 Ma. We divided the chronology into the Holocene (approximately 11 ka,MIS 1),the mid to late Pleis-tocene (approximately 11 ka to 600 ka,MIS 1 to MIS 15),and the early Pleistocene to late Pliocene (600 ka to 4000 ka,MIS 15 to MIS Gi24). We reviewed and summarized the glacial evolution history of the Larsemann Hills and adjacent areas over these periods. For the samples from the Larsemann Hills,we conducted a detailed discussion on the impact of erosion rates. We recalculated the exposure ages of the samples using erosion rates of 0 mm·a-1,0.0007 mm·a-1,and 0.0015 mm·a-1 (modern erosion rates). The results showed that erosion rates lead to a significant overestimation of exposure ages,and using modern erosion rates for correction resulted in model saturation. Finally,we discussed the relationship between exposure age and altitude by region. There was a clear pattern in the Prince Charles Mountains and Grove Mountains (alpine setting) but in the Larsemann Hills,Vestfold Hills,and Rauer Group (coastal setting),glaciers primarily retreated horizontally,showing no obvious pattern. We compared the multi-source homogenized data from different regions,and the following are reached:(1) 17.86％ of the samples have exposure ages less than 11 ka,83.16％ of the samples have exposure ages less than 600 ka,and 98.47％ of the samples have exposure ages less than 2.8 Ma. In some regions,there are still controversies regarding the ice retreat time determined by 10Be exposure dating. (2) The resultant in-crease amounts to 51.57％ when the erosion rate reaches 0.007 mm·a-1. When calculating exposure ages,it is important to consider reasonable erosion rates. (3) The exposure age tends to decrease with decreasing altitude. However,in low-altitude coastal areas,this trend may be offset by various factors,which require further re-search to explain. Future dating work in this area should be further promoted,and attention should be paid to erosion rate selection.
East AntarcticaLarsemann Hillsexposure agesice sheet history
万方数据
维普
