Cosmogenic ^(21)Ne concentrations and exposure ages of summit bedrocks in the Grove Mountains,Antarctica  

作　　者：KONG Ping1,2,DING Lin2,LAI QingZhou2 & HUANG FeiXin3 1 Key Laboratory of the Earth’s Deep Interior,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 2 Key Laboratory of Continental Collision and Plateau Uplift,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100085,China 3 Institute of Mineral Resources Research,China Metallurgical Geology Bureau,Beijing 100025,China 

出　　处：《Science China Earth Sciences》2010年第4期518-521,共4页中国科学（地球科学英文版）

基　　金：supported by National Natural Science Foundation of China (Grant No.40631004)

摘　　要：Various sources of 21Ne and 22Ne exist in surface rocks:cosmogenic,in situ nucleogenic from internal U and Th,trapped crustal nucleogenic and trapped atmospheric.This paper reports the first measurement,in China,of cosmogenic 21Ne and 22Ne in surface bedrocks.We developed a unique sample pre-treatment procedure that effectively removed inclusions inside quartz grains,and thus maximally reduced nucleogenic contributions of 21Ne and 22Ne.Step-heating experiments show that concen-trations of cosmogenic 21Ne and 22Ne in summit bedrock samples R9202 and R9203 from Grove Mountains,Antarctica,are(3.83±0.87)×108 and(5.22±0.51)×108 atoms/g,respectively.The corresponding minimum exposure ages are 2.2±0.5 and 3.0±0.3 Ma.This indicates that the ice sheet in East Antarctica was uncovered the crest of Mount Harding,a typical nunatak in Grove Mountains,since at least mid-Pliocene.Various sources of 21Ne and 22Ne exist in surface rocks:cosmogenic,in situ nucleogenic from internal U and Th,trapped crustal nucleogenic and trapped atmospheric.This paper reports the first measurement,in China,of cosmogenic 21Ne and 22Ne in surface bedrocks.We developed a unique sample pre-treatment procedure that effectively removed inclusions inside quartz grains,and thus maximally reduced nucleogenic contributions of 21Ne and 22Ne.Step-heating experiments show that concen-trations of cosmogenic 21Ne and 22Ne in summit bedrock samples R9202 and R9203 from Grove Mountains,Antarctica,are(3.83±0.87)×108 and(5.22±0.51)×108 atoms/g,respectively.The corresponding minimum exposure ages are 2.2±0.5 and 3.0±0.3 Ma.This indicates that the ice sheet in East Antarctica was uncovered the crest of Mount Harding,a typical nunatak in Grove Mountains,since at least mid-Pliocene.

关 键 词：21Ne COSMOGENIC NUCLIDE exposure age ANTARCTICA Grove MOUNTAINS 

分 类 号：P597.3[天文地球—地球化学]