Evidence of Glacial Erratic Rollover Revealed by ^(10)Be and ^(26)Al Concentration Variations  

作　　者：ZHANG Zhigang WANG Jian XU Xiaobin CHANG Zhiyang CUI Haitao LIANG Zhong CHEN Xia SHANG Zhiyuan 

机构地区：[1]School of Geography,Nanjing Normal University,Nanjing 210023,China [2]Key Laboratory of Virtual Geographic Environment(Nanjing Normal University),Ministry of Education,Nanjing 210023,China [3]State Key Laboratory Cultivation Base of Geographical Environment Evolution(Jiangsu Province),Nanjing 210023,China [4]Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing 210023,China [5]Jiangsu Second Normal University,Nanjing 210013,China [6]Tourism and Social Administration College,Nanjing Xiaozhuang University,Nangjing 211171,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第1期369-375,共7页地质学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant nos.41971009 and 41503054);the CASKJZD-EW-G03-04 project(Grant No.Y4422101001);the General Financial Grant of the China Postdoctoral Science Foundation(Grant No.2015M582728);the Priority AcademicProgram Development of Jiangsu Higher EducationInstitutions(Grant No.164320H116)。

摘　　要：Cosmogenic nuclide exposure dating is one of the most intensively applied dating methods with which to study glacial geomorphology.Glacial erratics have been the major dating objective in many studies.Some research has proposed that glacial erratics may undergo rollover and re-transportation during the late exposure stage,which can affect the dating results.However,there is no direct evidence to confirm this possibility.In this study,we collected seven samples from a vertical section inside a glacial erratic in the paleo-Daocheng ice cap in the southeastern Tibetan Plateau,measuring their contents of the cosmogenic nuclides ^(10)Be and ^(26)Al.The results show that from the top to the bottom,the concentrations of 10Be were(1.21±0.05)×10^(6),(1.00±0.02)×10^(6),(0.88±0.03)×10^(6),(0.77±0.02)×10^(6),(0.75±0.03)×10^(6),(0.95±0.03)×10^(6) and(1.46±0.04)×10^(6) atoms/g.The ^(10)Be concentrations decreased from(1.21±0.05)×10^(6) atoms/g to(0.75±0.03)×10^(6) atoms/g and then increased to(1.46±0.04)×10^(6) atoms/g,which is not consistent with the theoretical prediction of a gradual decrease.This phenomenon indicates that the glacial erratic may have rolled over at least once.The lower surface of the erratic could have been on top at some time in the past.Therefore,its exposure age was greater than the exposure age that was expected,based on its current orientation.This study provides numerical evidence for an erratic rollover event.

关 键 词：glacial erratics ^(10)Be and^(26)Al ROLLOVER Tibetan Plateau 

分 类 号：P343.6[天文地球—水文科学]