利用宇生核素^(10)Be暴露测年技术重建冰川漂砾运动历史  

Reconstructing Movement History of Glacial Boulders by Using ^(10)Be Exposure Dating Method

作　　者：张志刚[1,2,3,4,5] 王建[1,2,3,4] 徐孝彬 常直杨[7] 陈倩[1] ZHANG Zhigang WANG Jian XU Xiaobin CHANG Zhiyang CHEN Qianl(School of Geographical sciences, Nanjing Normal University, Nanjing Jiangsu 210023, China Key Laboratory of Virtual Geographical Environment, Nanfing Normal University, Nanfing, Jiangsu 210023, China State Key Laboratory Cultivation Base of Geographical Environment Evolution, Nanjing, Jiangsu 210023, China Jiangsu Genter for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, Jiangsu 210023, China State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanshou, Gansu 730000, China Jiangsu Second Normal University. Nanjing, Jiangsu 210024, China Nanjing Institute of Tourism and Hospitality, Nanjing, Jiangsu 210024, China)

机构地区：[1]南京师范大学地理科学学院,江苏南京210023 [2]虚拟地理环境教育部重点实验室(南京师范大学),江苏南京210023 [3]江苏省地理环境演化国家重点实验室培育建设点,江苏南京210023 [4]江苏省地理信息资源开发与利用协同创新中心,江苏南京210023 [5]中国科学院西北生态环境资源研究院冰冻圈国家重点实验室,甘肃兰州730000 [6]江苏第二师范学院,江苏南京210024 [7]南京旅游职业学院,江苏南京211100

出　　处：《山地学报》2017年第4期590-597,共8页Mountain Research

基　　金：国家自然科学基金项目(41503054);中国博士后科学基金项目(2015M582728);中国科学院重点部署项目(KJZD-EW-G03-04);江苏省高校优势学科建设工程资助项目(164320H116)~~

摘　　要：20世纪80年代兴起的宇生核素暴露测年技术是目前冰川地貌研究中最为成功的测年方法之一,多数学者通常选择冰川漂砾进行暴露测年研究。然而,冰川漂砾在出露后期可能经过再次搬运造成"翻转"现象,从而影响测年结果。重建这类翻转漂砾的运动历史,对准确测定冰川地貌年代具有重要意义。青藏高原东南部的稻城古冰帽区保存了大量的古冰川遗迹,是宇生核素暴露测年研究的天然实验室。冰帽区有一被人为劈开的巨型漂砾,其内部垂直剖面上底部样品的宇生核素^(10)Be浓度高于顶部样品,推断该漂砾自初次出露之后可能发生过翻转。本文利用该漂砾顶部、底部、左右侧面的样品通过宇生核素^(10)Be暴露测年技术来重建该漂砾的运动历史。研究结果表明:该漂砾可能是由于深海氧同位素3阶段(Marine Isotope Stage,简称MIS 3)冰川作用暴露于地表,随后经过翻转直至目前状态。Cosmogenic nuclide^10Be exposure dating is one of the most successful dating methods used to study glacial geomorphology since 1980 s. In most studies,glacial erratics have been preferred for exposure dating material. However,glacial erratics may have undergone re-transportation and roll-over during the post-exposure stage,which can affect the dating results. Reconstructing the movement history of these boulders is therefore of crucial importance for obtaining reliable chronology of glacial landform by exposure dating of glacial erratics. The paleo-Daocheng ice cap in the southeastern Tibetan Plateau exhibits abundant glacial remnant and provides an ideal natural laboratory for cosmogenic nuclides exposure dating. A big boulder,found in the Daocheng ice cap,was split because of road construction. Concentrations of^10Be in the bottom sample were more than the top sample,which indicated that the boulder might have rolled over during the post-exposure period. In this study,samples from the top,bottom,left and right side of the boulder were selected and used to reconstruct the movement history by using^10Be exposure dating method. The result demonstrated that the boulder might have been exposed to the surface due to the glacial advance during Marine Isotope Stage（ MIS 3）,and thereafter undergone several times retransportation and roll-over events.

关 键 词：宇生核素 漂砾 ^10BE 翻转 青藏高原 

分 类 号：P931.4[天文地球—自然地理学]