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冰川冻土 ›› 2016, Vol. 38 ›› Issue (5): 1292-1299.doi: 10.7522/j.issn.1000-0240.2016.0151

• 冰冻圈与全球变化 • 上一篇    下一篇

ESR测年技术在第四纪冰川年代学中的研究综述

毕伟力, 易朝路   

  1. 中国科学院 青藏高原研究所, 北京 100101
  • 收稿日期:2016-04-11 修回日期:2016-08-21 出版日期:2016-10-25 发布日期:2017-01-22
  • 作者简介:毕伟力(1986-)女,辽宁辽阳人,2013年硕士毕业于辽宁师范大学,现为中国科学院青藏高原研究所在读博士研究生,主要从事冰川与环境变化研究.E-mail:biweili@itpcas.ac.cn.
  • 基金资助:

    国家自然科学基金(41271018;40971017)资助

Review of ESR dating technique in Quaternary glacial chronology

BI Weili, YI Chaolu   

  1. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
  • Received:2016-04-11 Revised:2016-08-21 Online:2016-10-25 Published:2017-01-22

摘要:

近些年,宇宙成因核素暴露年代、光释光和放射性碳埋藏年代等方法在第四纪冰碛物的年代测定中已经取得显著进展.但对于第四纪冰川沉积物10万年甚至百万年以上的冰碛物样品的埋藏年代和暴露年代,由于方法自身问题或沉积物后期地质地貌过程的改造,使上述方法存在定年方面的挑战.而电子自旋共振(ESR)广泛的测年范围,使其在第四纪样品的测年中发挥着不可替代的作用.目前,石英ESR信号的衰退特征已有许多研究进展,但是对于冰碛物中的ESR信号的研究还很少.ESR测年方法由于缺乏测年机理的研究,西方学者和国内一些测年学者对这种方法的定年存有疑虑.因此,我们在典型冰川区开展对冰碛物中石英砂ESR信号变化的机理研究,得到人工研磨可以使ESR信号强度下降到原来值的53%~69%,但并不能使ESR信号完全归零.如果在以后的研究中能够找出这些残留信号值大小,并予以扣除,将会大大提高ESR冰碛物测年精度.在今后的研究中应探求其测年机理,提高测试样品的石英纯度,增强ESR测年信号的精度,使这种方法成为冰碛物交叉测年中独立可信的测年方法之一,为第四纪冰川研究中的老冰碛物的定年提供准确的年代依据.

关键词: ESR测年, Ge心, 第四纪, 冰川年代学

Abstract:

In recent years, remarkable progress has been made in Quaternary glacial-chronology with the development of several numeric dating techniques, such as cosmogenic nuclides (NC), optically stimulated luminescence (OSL) and 14C. In contrast, the dating of Quaternary glacial tills older than 100,000 years has been a challenge, because the present techniques have defects themselves. In addition, the sediments have been disturbed during transportation and sedimentation. Electron Spin Resonance (ESR) has advantages over these techniques. It can date moraine features older than 100,000 years or up to million-year scale. The mechanism to reset ESR time clock is fundamental for application of this technique in dating. A series of laboratory simulation and field observation studies were carried out. Researchers found that ESR signal intensity in germanium center of quartz grains detected from the manually ground samples would be decreased to 53%~69% of its original value, but would not be reduced to zero. If this residual signal could be determined and removed, the accuracy of ESR dating of glacial tills could be greatly improved. In the future, more research should be carried out to look into the mechanisms of dating, to improve the purity of quartz in test samples, and thus to improve the accuracy of ESR dating signal. Thus, ESR dating will become of the most independent and credible cross-dating methods and provide accurate dating of the ancient glacier tills for Quaternary glaciation research.

Key words: ESR dating, Ge center, Quaternary, glacial chronology

中图分类号: 

  • P343.6