Isotopic Geochemistry of Oceanic Mantle Sections and the Dating of Quaternary Volcanics

这一建议的目的是：1)深入研究基性和超镁铁质岩石中Re-Os、Sm-ND、Rb-Sr系和铂族元素的同位素地球化学，以研究地幔来源、分异产物及其在显生界的演化；2)U、Th衰变系列的230th等中间子体在全新世和晚更新世火山岩测年中的应用及其与岩浆来源和斑晶形成时代的关系。除了手头的样本外，还将在关键地点进行实地工作，以获取非常新的材料。这些问题将在三年内解决，使用新开发的铂族元素负热离子质谱仪的质谱学技术和新一代高丰度灵敏度质谱仪(丰度灵敏度优于5×10-10(2 Amu))和高透射率。最近开发的分析化学方法将被用来在超低浓度下有效地分离元素，并且污染可以忽略不计。这项工作应该会对要研究的岩石的起源产生新的科学理解，以及改进分析技术的发展。

This proposal is to conduct: 1) an in depth study of the isotopic geochemistry of the Re-Os, Sm-Nd and Rb-Sr systems and of platinum group elements in basic and ultramafic rocks for the purpose of studying mantle sources, their differentiation products,and their evolution over the Phanerozoic; and 2) the application of 230Th and other intermediate daughters of the U and Th decay series to the dating of Holocene and late Pleistocene volcanics and the relationship of these volcanics to magma sources and the times of formation of phenocrysts. In addition to samples at hand, filed work will be conducted to obtain very fresh materials at key localities. These problems will be attacked over a three-year period, using newly developed mass spectrometric techniques of negative thermal ion mass spectrometry of the platinum group elements and a new generation high abundance sensitivity mass spectrometer (abundance sensitivity better than 5 x 10-10 for 2 amu) with high transmission. Recently developed analytical chemical procedures will be used to separate elements at ultra low level concentrations efficiently and with negligible contamination. This work should result in new scientific understanding on the origins of the rocks to be studied, as well as the development of improved analytical techniques.