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Pd-Ag chronometry of iron meteorites and the accretion and thermal history of differentiated protoplanets

铁陨石的 Pd-Ag 测年法以及分化原行星的吸积和热史

基本信息

批准号：
182743398
负责人：
Dr. Mario Fischer-Gödde
金额：
--
依托单位：
Institut für Geologie und Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/182743398?language=en
关键词：
Pd Ag chronometry iron meteorites

项目摘要

Short-lived radionuclides play a pivotal role in understanding the early history of the solar system. They provide information on the sequence of several key events, including the time-scales of the condensation of the first solids and the accretion and differentiation of planetary bodies. Such age constraints are essential for understanding planet formation and for constraining the parameters that controlled the subsequent evolution of planetary bodies. For example, Hf-W dating of iron meteorites revealed that their parent bodies accreted well before the chondrite parent bodies, a result that has led to revision of almost all models of early solar system development. The Hf-W results demonstrate that iron meteorites are remnants of some of the oldest protoplanetary bodies formed in the inner solar system and as such they play a pivotal role in the understanding of the earliest stage of planet formation. This proposal aims at providing new and firm constraints on the chronology of these differentiated protoplanets. We will focus on the thermal history of iron meteorite parent bodies and aim to constrain the cooling history of the major groups of magmatic irons using the short-lived 107Pd-107Ag chronometer. One of the major expected outcomes of this study will be a refined time scale for the differentiation and cooling history of some of these early-differentiated protoplanets. The Pd-Ag isotopic study will be combined with a detailed and quantitative assessment of the Pd-Ag closure temperature. Furthermore, the initial Pd and Ag isotopic compositions, both of which are not well defined, will be determined precisely. This integrated approach will provide important new constraints on the sizes, internal structure and early history of some of the oldest protoplanetary bodies.

短寿命放射性核素在了解太阳系早期历史方面发挥着关键作用。它们提供了关于几个关键事件的顺序的信息，包括第一个固体凝结的时间尺度和行星体的吸积和分化。这种年龄限制对于理解行星的形成和限制控制行星体随后演化的参数至关重要。例如，铁陨石的Hf-W测年显示，它们的母体在球粒陨石母体之前就已经增生，这一结果导致了几乎所有早期太阳系发展模型的修正。Hf-W的结果表明，铁陨石是内太阳系中形成的一些最古老的原行星体的残余物，因此它们在理解行星形成的最早阶段中发挥着关键作用。这一提议旨在对这些分化的原行星的年表提供新的和坚定的限制。我们将专注于铁陨石母体的热历史，并旨在使用短寿命的107 Pd-107 Ag计时器来限制岩浆铁的主要群体的冷却历史。这项研究的主要预期成果之一将是一些早期分化的原行星的分化和冷却历史的精确时间尺度。Pd-Ag同位素研究将与Pd-Ag闭合温度的详细和定量评估相结合。此外，初始的Pd和Ag同位素组成，这两者都不是很好地定义，将被精确地确定。这种综合方法将对一些最古老的原行星体的大小、内部结构和早期历史提供重要的新限制。