Re-Os Isotopic Studies of Crust-Mantle Evolution on the Earth

Re-Os同位素系统具有对地球地球化学研究作出贡献的独特潜力，因为该系统提供的信息将补充目前从其他同位素系统获得的信息，并应对地幔的地球化学演化、核的形成和陆壳的形成提供新的见解。该项目将确定准确的地幔Os同位素生长曲线，估算3.6Ga克拉通岩芯母体的地壳停留时间，更好地了解Re和Os在火成岩系统中的行为，并估计现代地幔的Os同位素不均一性。技术将基于J.Fassett和DTM研究助理R.J.Walker在国家标准局(NBS)正在进行的工作。资金将主要用于支付沃克的工资，并在DTM建造一个用于分离Re和O的化学设施。首先，将在国家统计局的Fassett-Walker 6英寸RIMS机器上使用激光共振电离质谱仪(RIMS)进行分析。随后，将使用目前正在DTM建造的改进的9英寸质谱仪。

The Re-Os isotope system has unique potential to contribute to geochemical studies of the earth because information provided by this system will be complementary to that currently available from other isotope systems and should provide new insight on the geochemical evolution of the mantle, formation of the core and creation of continental crust. This project will determine an accurate Os isotope growth curve for the mantle, estimate the crustal residence time of the parents of 3.6 Ga craton core rocks, better understand the behavior of Re and Os in igneous systems and estimate the Os isotope heterogeneity of the present mantle. Techniques will be based on the ongoing work at the National Bureau of Standards (NBS) of J. Fassett and DTM Research Associate R. J. Walker. Funds will be used primarily to pay Walker's salary and to build a chemical facility at DTM for the separation of Re and Os. Initially, analyses will be performed by laser resonance ionization mass spectrometry (RIMS) on the Fassett-Walker 6" RIMS machine at NBS. Later, an improved 9" mass spectrometer, presently under construction at DTM, will be used.