Re-Os同位素在晚新元古代至早寒武世测年及古环境演绎中的应用进展  

Research Progress on Re-Os Isotopes Application in Dating and Paleoenvironmental Interpretation during the Neoproterozoic to Early Cambrian Periods

作　　者：王富良[1] 付勇[1,2] 江冉[1] 周文喜[1] 葛枝华 魏帅超 梁厚鹏 张鹏[1] 

机构地区：[1]贵州大学资源与环境工程学院,贵州贵阳550000 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《岩矿测试》2016年第5期530-541,共12页Rock and Mineral Analysis

基　　金：国家自然科学基金资助项目(41203037);贵州大学人才引进基金((2011)17);贵州大学研究生创新基金资助项目(研理工2016044)

摘　　要：晚新元古代至早寒武世是地球演化历史上极其重要的时期,该时期地层年龄框架的厘定以及古海水、古大气、古气候等方面的研究一直是国际地学界的关注热点。Re-Os同位素测年法是近十几年来兴起的地层测年法,其对于晚新元古代至早寒武世重要时间节点上沉积的富有机质黑色页岩具有测年及示踪古环境的双重优势。本文以晚新元古代至早寒武世地层为例,阐述了Re-Os同位素测年法在年代地层学研究中的应用,通过与大量的、精确的锆石U-Pb年龄对比,论证了Re-Os同位素测定沉积地层年龄的可靠性。对于震旦系陡山沱组地层建阶及留茶坡组地层的年代学研究,黑色页岩Re-Os同位素测年法可发挥重要的作用。结合前人所做的Sr同位素变化曲线以及收集的晚新元古代—早寒武世Os同位素初始值的测试数据,阐述了Os同位素在该时段古环境演绎及Ni-Mo-V多金属层来源追溯上发挥的作用。黑色页岩难以进行^(87)Sr/^(86)Sr的分析,而Os同位素初始值能较好地弥补这一缺陷,二者的相互结合将为晚新元古代至早寒武世古环境演化的研究作出贡献。本文指出,随着Re-Os同位素分析技术的发展以及更多实验流程的建立,该项技术在未来年代地层学,尤其对一些古老地层的年代厘定具有广阔的应用前景。The Neoproterozoic to Early Cambrian period is a very important era in the history of earth evolution. Research on stratigraphic framework, paleo-oceanography, palaro- atmospheric, and paleoclimatology are focuses of international geosciences. As a new stratigraphic dating method, Re-Os isotopic dating was developed rapidly in the last decades. It has dual advantages of dating and tracing the paleoenvironment for the organic-rich black shale deposited at the important timing turning points during Neoproterozoic to Early Cambrian.Taking the Neoproterozoic to Early Cambrian strata as an example, the application of the Re-Os isotopic dating method in chronostratigraphy is described in this paper and the reliability of the Re-Os dating method by comparison with numerous precise zircon U-Pb ages is confirmed. This method has played an important role in the research of the building order in the Doushantuo Formation and the sedimentary time of the Liuchapo Formation. Combining previous Sr isotope curves with the initial ^187 Os/^188 Os ratios of Neoproterozoic to Early Cambrian strata, the role of Os isotopes in the interpretation of the paleoenvironment and tracing the source of Ni-Mo-V polymetallic layers is discussed. Sr isotope analysis is difficult to conduct on black shales, while initial ^187Os/^188 Os can complement this defect. Therefore, the mutual combination of these two methods can contribute to the exploration of the paleoenvironment during Neoproterozoic to Early Cambrian. Finally, with the development of Re-Os isotope analysis technology and establishment of more experiment processes, it will produce a significant effect on the study of future chronostratigraphy, especially on the age- determination of the older strata.

关 键 词：黑色页岩 RE-OS同位素 ^187Os/^188Os初始值 早寒武世 晚新元古代 华南地区 

分 类 号：P619.227[天文地球—矿床学] P597.3[天文地球—地质学]