Tracing Early Earth Evolution

本研究计划建议使用贵金属及其放射性同位素来解决固体地球化学中一些最长期和最具争议的问题。地核的形成应该在地球其他部分的化学成分上留下了不可逆转的印记。然而，如果地核形成是地幔演化的唯一控制因素，那么许多贵金属，如铂族元素（PGEs），在地幔中仍然“过剩”。这表明地幔在其形成后不久的某一时刻再次富集。新的研究揭示了pge短暂富集的迹象，在核心形成后近20亿年达到顶峰。我计划利用加拿大北极地区古代“绿岩带”的岩浆岩，对这种再富集的时间和性质进行详细调查。了解地球地幔的早期演化对我们了解地球从最初的吸积到今天的化学和物理演化具有重要意义。一些火山岩独特的新鲜性质使得研究地球历史上这一关键时期的地球化学变化成为可能，

This research program proposes to use precious metals and their radiogenic isotopes to address some of the most long-standing and controversial issues in solid Earth geochemistry. The formation of the Earth's core should have left an irreversible imprint on the chemistry of the rest of the Earth. Yet many precious metals, such as the platinum group elements (PGEs), remain "over-abundant" in the mantle if core-formation was the sole control on its evolution. This indicates that the mantle was re-enriched at some point soon after its formation. New research has revealed hints of a temporal enrichment in PGEs that peaked almost 2 billion years after core formation. I plan a detailed investigation into the timing and nature of this re-enrichment, using magmatic rocks in Arctic Canada's ancient "greenstone belts". Understanding the early evolution of the Earth's mantle has fundamental implications for our knowledge of how the Earth evolved chemically and physically, from its initial accretion, to today. The uniquely fresh nature of some of the volcanic rocks allow investigation of geochemical changes in this critical period of Earth history,