天山乌鲁木齐河源末次冰期冰川沉积光释光测年  

OSL dating on glacial sediments of the Last Glacial in headwater of Urumqi River, Tianshan Mountains

作　　者：曾兰华[1] 欧先交[1,4] 陈嵘 赖忠平[3] ZENG Lanhua;OU Xianjiao;CHEN Rong;LAI Zhongping(School of Geography and Tourism,Jiaying University,Meizhou 514015,Guangdong,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;Institute of Marine Science,Shantou University,Shantou 515063,Guangdong,China;Department of Geography and Earth Sciences,Aberystwyth University,Ceredigion SY233DB,UK)

机构地区：[1]嘉应学院地理科学与旅游学院,广东梅州514015 [2]中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,江苏南京210008 [3]汕头大学海洋科学研究院,广东汕头515063 [4]Department of Geography and Earth Sciences,Aberystwyth University,Ceredigion SY233DB,UK

出　　处：《冰川冻土》2019年第4期761-769,共9页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目（40901011;41371080）资助

摘　　要：乌鲁木齐河源地区是中国冰川遗迹保存最丰富、地貌最典型的区域之一,是根据冰川遗迹重建第四纪冰川历史的理想地区。大量的研究工作以及技术测年结果也使其成为试验冰川沉积光释光(optically stimulated luminescence,OSL)测年可行性的理想地点。共采集了6个冰碛及上覆黄土样品用于光释光测年。提取38~63μm的石英颗粒,运用SAR-SGC法测试等效剂量。各种检验表明测试程序是适用的。通过地貌地层关系、重复样品、已有年代的对比等方法,检验该地冰川沉积OSL测年的可行性。结果表明,OSL年代结果与地貌地层新老关系非常吻合,与已有的其他测年技术的年代结果也具可比性,表明这些样品的OSL信号在沉积之前晒退较好,OSL年代是可信的。冰川观测站侧碛垄的OSL年代为14.8±1.2ka;9号冰川支谷口附近冰碛的OSL年代为13.5±1.1ka和17.2±1.3ka;上望峰冰碛的OSL年代为20.1±1.6ka。综合OSL年代结果与此前其他测年结果,这几套冰碛垄形成于深海氧同位素MIS2阶段应该是比较统一的认识。上望峰冰碛上覆黄土的OSL年代(10.5±0.8ka)也印证了该结论。OSL年代指示上望峰冰碛对应于末次冰期最盛期,冰川观测站和9号冰川支谷谷口冰碛对应于晚冰期。下望峰冰碛的OSL年代为36.3±2.8ka,对应于MIS3阶段。下望峰冰碛的形成时代,仍有待更多沉积学以及测年工作进一步确定。The headwater of Urumqi River is one of the areas with most abundant glacial relics and most typical glacial landforms in China. It is an ideal site for reconstructing the history of Quaternary glaciation based on glacial relics. Numerous studies and technical dating results make it an ideal site to test the applicability of optically stimulated luminescence(OSL)dating of glacial sediments. Six till and overlying loess samples were collected for OSL dating. The 38-63 μm quartz grains were extracted and the equivalent dose was measured by SARSGC method. Various tests show that the procedure is applicable. The reliability of OSL dating of glacial sediments is tested by comparisons with geomorphological and stratigraphical relationship and known ages. The results show that the OSL ages are in good agreement with the geomorphological and stratigraphical relationship,and are comparable with ages of other dating techniques. These indicate that the samples had been well bleached before deposition and the OSL ages are reliable. The OSL age of the lateral moraine near the Tianshan Glaciological Station is 14.8±1.2 ka;till samples near the mouth of the branch valley of Glacier No.9 are 13.5±1.1 ka and 17.2±1.3 ka;OSL age of the Upper Wangfeng moraine is 20.1±1.6 ka. Based on the OSL ages and previous dating results,it can be concluded that these sets of moraines were formed during the marine oxygen isotope stage 2(MIS2). The OSL age of loess overlying the Upper Wangfeng moraine (10.5±0.8 ka)further confirms this conclusion. OSL ages also indicate that the Upper Wangfeng moraine corresponds to the Last Glacial Maximum(LGM),while moraines near the Tianshan Glaciological Station and the mouth of the branch valley of Glacier No.9 correspond to Late Glacial. The OSL age of Lower Wangfeng moraine is 36.3±2.8 ka,which corresponds to the MIS3 stage. However,the forming time of Lower Wangfeng moraine requires further confirmed by more sedimentology and chronology works.

关 键 词：冰川沉积 光释光测年 望峰冰碛 末次冰期 晒退 天山 乌鲁木齐河源 

分 类 号：P931.4[天文地球—自然地理学]