Tracing Early Earth Evolution

追踪早期地球演化

• 批准号: 418398-2013
• 负责人: Pearson, Graham
• 金额: $ 5.97万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=661809
• 关键词: Tracing; Early; Earth; Evolution

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, ** Many important precious metal deposits were generated in the earliest phases of Earth history, within the Archean eon (3.8 and 2.5 Ga) and so understanding how PGE abundances may have changed with time in the mantle has an important bearing on the origin of Archean precious metal deposits. Moreover, greenstone belts are host to major base-metal, gold and PGE deposits in Canada and globally, hence understanding their genesis and time of eruption is crucial for mineral exploration. The research program will provide training in state-of-the-art geochemical techniques that have applications in several high-tech industries and will train HQP in Arctic geology and field techniques . The research builds on my international reputation, established in the UK, for leadership in platinum group element and Os isotope research applied to diverse geological and biochemical/pharmacological problems. The techniques to be established for this research program do not yet exist in Canada and so will enhance Canada's reputation as a leader in the field of solid-Earth geochemistry.

该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存在和最有争议的问题。 地核的形成应该对地球其他部分的化学性质留下了不可逆转的印记。 然而，许多贵金属，如铂族元素（PGEs），仍然是“过度丰富”的地幔，如果核心的形成是唯一的控制其演变。 这表明地幔在其形成后不久的某个时刻再次富集。 新的研究揭示了PGEs在时间上富集的迹象，在核心形成后近20亿年达到峰值。 我计划对这种再富集的时间和性质进行详细的调查，使用加拿大北极古老的“绿岩带”中的岩浆岩。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根本意义。 一些火山岩独特的新鲜性质允许在地球历史的这一关键时期调查地球化学变化，** 许多重要的贵金属矿床产生于地球历史的最早阶段，在太古代（3.8和2.5 Ga），因此了解PGE丰度如何随时间在地幔中变化对太古代贵金属矿床的起源具有重要意义。此外，绿岩带是加拿大和全球主要贱金属、金和铂族元素矿床的所在地，因此了解其成因和喷发时间对矿产勘探至关重要。 该研究计划将提供最先进的地球化学技术的培训，这些技术在几个高科技行业都有应用，并将对HQP进行北极地质和现场技术的培训。这项研究建立在我在英国建立的国际声誉之上，在应用于各种地质和生物化学/药理学问题的铂族元素和Os同位素研究方面发挥着领导作用。 为这一研究方案建立的技术在加拿大尚不存在，因此将提高加拿大作为固体地球化学领域领导者的声誉。