地球科学进展 ›› 2005, Vol. 20 ›› Issue (4): 414 -420. doi: 10.11867/j.issn.1001-8166.2005.04.0414

研究论文 上一篇    下一篇

洞穴碳酸盐 230Th- 234U- 238U测年初始钍校正的等时线研究
蔡演军 1,Cheng Hai 2,安芷生 1,Edwards R. Laurence 2,王先锋 2,Shen Chuan-Chou 3   
  1. 1.中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,陕西 西安 710054;
    2.Department of Geology and Geophysics, University of Minnesota, MN 55455 USA;
    3.Department of Geosciences, National Taiwan University, Taipei 106, China
  • 收稿日期:2004-01-19 修回日期:2004-10-12 出版日期:2005-04-25
  • 通讯作者: 蔡演军
  • 基金资助:

    中国科学院知识创新工程重要方向项目“我国自然环境分异耦合过程与发展趋势”(编号:KZCX2-SW-118); 中国科学院知识创新工程重要方向项目“我国环境敏感带全新世温暖期的高分辨率环境记录”(编号:KZCX3-SW-120)资助.


CAI Yanjun 1;Cheng Hai 2;AN Zhisheng 1;Edwards R. Laurence 2;WANG Xian-feng 2;SHEN Chuanchou 3   

  1. 1.State Key Labatory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710054, China;
    2.Department of Geology and Geophysics,University of Minnesota, MN 55455 USA;
    3.Department of Geosciences, National Taiwan University, Taipei 106, China
  • Received:2004-01-19 Revised:2004-10-12 Online:2005-04-25 Published:2005-04-25


The correction of initial 230Th is very important for the 230Th-234U-238U dating of impure speleothem. The corrected 230Th ages usually assume an initial 230Th/232Th atomic ratio of (4.4±2.2)×10-6. During the last 30 years, various leach-leach, leach-residue methodologies have been promoted to distinguish between the isotopic ratios in the authigenic and detrital phases, and the total dissolution techniques are the most reliable method to setup meaningful isochrones. In this paper, Uranium and Thorium isotopic composition of 9 sub-samples in two different layers of stalagmite MN04 have been analyzed and the respective isochrones have also been setup. The results show that the initial 230Th/232Th atomic ratio of the sub-samples from up layer is (3.5±2.8)×10-6,and that of from down layer is (10.6±2.2)×10-6. It suggests that, even in the same area, the initial 230Th/232Th atomic ratio in various layers of the same stalagmite could have sizable difference because of the complicated origin of the detrital thorium. Therefore, it is insufficient to use the initial 230Th/232Th ratio obtained from the single isochron to correct the whole sample as well as other samples from the same area. Considering the high content of 232Th would also have significant influence on the measurement of 230Th, choosing pure carbonates to the best in sample selecting and preprocessing will greatly reduce the age deviation caused by the incorporated detrital thorium.


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[1] 蔡演军;ChengHai;安芷生;EdwardsR.Laurence;王先锋;ShenChuan-Chou. 洞穴碳酸盐230Th-234U-238U测年初始钍校正的等时线研究[J]. 地球科学进展, 2005, 20(4): 414-420.