秦岭“太白冰期”冰坎宇宙成因核素^(10)Be定年  

Cosmogenic nuclide ^(10)Be dating of the glacial threshold of the “Taibai glaciation” in the Qinling Mountain range

作　　者：张威[1] 刘亮[1] 刘啸[1] 赵徐[1] 刘蓓蓓[1] 

机构地区：[1]辽宁师范大学城市与环境学院,大连116029

出　　处：《科学通报》2014年第31期3086-3094,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(41271093;41230743;40971010)资助

摘　　要：太白山(3767 m)是我国东部公认发育过第四纪冰川的山地,研究该区的第四纪冰川发育历史以及规模对第四纪环境演变具有重要的科学意义.然而,本区的第四纪冰川发生时代长期以来没有得到很好的解决,只有外国学者Rost在黑河谷地上游的内侧碛垄进行热释光(TL)断代,认为冰川发生的时限距今大约19 ka,对应末次冰盛期.本文运用陆生宇宙成因核素法(TCN)对三爷海、二爷海冰坎基岩暴露面进行了10Be定年,时代距今为18.62±1.08~16.87±0.95,16.88±1.08~15.07±0.92 ka,表明该区在末次冰期晚期经历了显著的冰川作用.根据三爷海到二爷海的直线距离和高差以及两级冰坎的平均暴露年代,在不考虑晚冰期和冰后期气候差异的情况下,推断冰川在水平和垂向上的退缩速度分别为0.396和0.09 m a?1,冰川在0.73~1.3 ka之间脱离山顶,永久积雪从此消失不见.Taibai Mountain（3767 m）, the main peak of the Qinling mountain range in eastern China, preserves typical Quaternary glacial remains. The timing and extent of the Quaternary glaciation in the study area has important scientific significance for reconstructing Quaternary environmental change. However, the absolute ages of the glaciation have not previously been well resolved. Using terrestrial in situ cosmogenic nuclides, we dated four samples collected from the surface of the Sanyehai and Eryehai glacial thresholds near the main peak. The results show that significant glacial retreat took place in two stages during the late part of the last glacial cycle at 18.62±1.08 to 16.87±0.95 ka and 16.88±1.08 to 15.07±0.92 ka. From the horizontal and vertical distances from the Sanyehai and Eryehai glacial thresholds, and neglecting the climate difference during the late stage of the last glacial cycle and the post-glacial stage, the horizontal and vertical retreat rates were 0.396 and 0.09 m a^-1, respectively. The retreat rates also show that glaciers and permanent snow disappeared from the main peak at about 0.73 to 1.3 ka.

关 键 词：太白山 冰坎 末次冰期 10Be 

分 类 号：P343.6[天文地球—水文科学] P534.63[天文地球—地球物理学]