Further development and application of the ReOs isotope system in crustal geochronology

地质年代学是利用地球物质（岩石、矿物、矿石）中不稳定同位素的放射性衰变来确定绝对地质年代的科学。地球年代学需要将物理、化学和数学与地球科学相结合，以了解在46亿年的历史中塑造我们星球的过程。铼锇（187Re-187Os）放射性同位素系统是地球科学中最后实施的系统之一，主要是由于分析困难。虽然Re-Os系统只适用于选定的地壳岩石和矿物，但这些岩石和矿物类型恰好是更常用的放射性定年系统（如U-Pb、Ar-Ar和Rb-Sr）通常不能用于提供年龄的岩石和矿物类型。拟议的研究将集中于三个项目，在这些项目中，准确和精确的地壳地质年代学将为与区域和全球尺度的地壳过程有关的知识提供重大的科学进展。Re-Os年代学研究将通过对世界各地不同盆地的含有机质页岩定年，应用于地球元古代的演化。这项研究的目的是：1 .为与全球冰川作用有关的关键元古代地层提供绝对年龄控制；2 .为地球历史上具有生物关键意义的埃迪卡拉系（635-542 Ma）提供精确年龄控制，以评估和检验地球表面条件变化（冰川作用）与生物进化之间的因果关系模型。第二个项目将使用常见的硫化物矿物，如黄铁矿，使用Re-Os方法来限制沉积盆地中流体流动事件的时间。同样，沉积盆地中烃类（油）的生成和流动也可以用re - o直接定年。将这两种方法结合起来研究同一盆地的含水流体和烃类流体流动，将为测试盆地流体流动背后驱动地质力量的各种模型提供关键的时间信息。最后，对石油中Re和Os的基本性质进行研究，为Re-Os同位素系统在石油勘探中的实施提供良好的依据。

Geochronology is the science of determining absolute geological time using radioactive decay of unstable isotopes in Earth materials (rocks, minerals, ores). Geochronology requires integration of Physics, Chemistry and Mathematics with the Geosciences to understand the processes that have shaped our planet over a 4.6 billion year history. The rhenium-osmium (187Re-187Os) radioactive isotope system is one of the last to be implemented in the Geosciences, due mainly to analytical difficulties. Although the Re-Os system is only applicable to selected crustal rocks and minerals, these happen to be the rock and mineral types for which the more commonly used radioactive dating system such as U-Pb, Ar-Ar and Rb-Sr cannot generally be used to provide age dates. The proposed research will focus on three projects in which accurate and precise crustal geochronology will provide a major scientific advancement of knowledge relating to regional and global-scale crustal processes. Research in Re-Os geochronology will applied to the evolution of the Proterozoic Earth by dating of organic-bearing shales from a variety of basins worldwide. The aims of the research are to: 1/ provide absolute age control for key Proterozoic strata associated with global glaciations and 2/ To provide precise age control for the biologically-critical Ediacaran System in Earth history (635-542 Ma) with which to evaluate and test models of cause-effect between changes in the Earth's surface conditions (glaciations) and biological evolution. The second project will use common sulfide minerals like pyrite to constrain the timing of fluid flow events in sedimentary basins using the Re-Os method. Similarly, the generation and flow of hydrocarbons (oil) in sedimentary basins can be directly dated using Re-Os. Coupling both these methods to study aqueous and hydrocarbon fluid flow in the same basin will provide critical timing information with which to test the various models of the driving geological force(s) behind basinal fluid flow. Lastly, a study of the fundamental nature of Re and Os in oil will be undertaken to provide a sound basis for the implementation of the Re-Os isotope system in petroleum exploration.