Isotopic and Geochemical Studies of Meteorites: Constraints on Processes and Time Scales in the Early Solar System and Implications for Early History of the Earth

9725659 Wadhwa本提案的主要目标是通过对陨石的地球化学和同位素研究，更好地限制太阳系早期的凝结、吸积和分异过程及其年代学。 拟议中的研究不仅对小行星带中星子的形成有影响，而且对地球的早期历史也有影响。 该工作计划由关于未分化和分化陨石的两条研究主线组成，并涉及长寿和短命（“灭绝”）计时系统的同位素测量。 第一个项目涉及的Al-Mg，Mn-Cr和初始Sr同位素系统的耐火钙铝丰富的包裹体（CAIs）从原始的碳质方解石的测定，并具有高分辨率的年代学的早期太阳系相对于这些最早形成的冷凝物的影响。 第二个项目涉及钯矿中磷酸盐的Sm-Nd系统学测定，以确定其小行星母体上核幔分离的时间。 这两个项目所提供的限制将提供一个更好的解决图片的时间和地球化学后果的早期过程中运行的内太阳系。

9725659 Wadhwa The main goal of this proposal is to gain better constraints on early condensation, accretion and differentiation processes and their chronology in the solar system through geochemical and isotopic studies of meteorites. The proposed research has implications not only for the formation of planetesimals in the asteroidal belt, but also for the early history of the Earth. The work plan is comprised of two main lines of research on undifferentiated and differentiated meteorites and involves isotopic measurements of long-lived and short-lived ("extinct") chronometric systems. The first project involves the determination of Al-Mg, Mn-Cr and initial Sr isotopic systematics in the refractory calcium-aluminum-rich inclusions (CAIs) from primitive carbonaceous chondrites and has implications for high-resolution chronology of the early solar system relative to these earliest formed condensates. The second project involves the determination of Sm-Nd systematics of phosphates in pallasites to establish the timing of core-mantle segregation on their asteroidal parent body. The constraints offered by these two projects will provide a better resolved picture of the timing and geochemical consequences of the early processes operational in the inner solar system.