Exploring the Hadean Earth

探索冥古宙地球

• 批准号: 0635969
• 负责人: Timothy Harrison
• 金额: $ 32.03万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635969&HistoricalAwards=false
• 关键词: Exploring; Hadean; Earth

The first 500 million years of Earth history (4.5 to 4.0 billion years), known as the Hadean Eon, is the planet's 'dark age' as no rock older than 4 billion years are known in the geologic record. However, sand-grain sized crystals of the mineral zircon are found in younger quartzite rocks that are dated to almost as old as the Earth itself. Preliminary analyses suggest the possibility that the very early Earth shared more in common with present day than previously thought. This surprising result requires detailed examination, but Hadean grains are very rare, making up only about one part in a million of the sedimentary rock. Following an intensive analysis program, the lead scientist and his team have archived several hundred Hadean zircons and in this project, they plan to undertake experiments that may give us unprecedented insights into Earth's earliest evolution. The questions to address are the following: 1) Did early Earth differentiation include massive production of continental crust? 2) Did a mechanism akin to plate tectonics operate during the Hadean? 3) Why are rocks older than 4 billion years non-existent? 4) When did the atmosphere form? 5) Were there oceans during the Hadean Eon? 6) Are any of these ancient zircons of extra-terrestrial origin? To address these questions, the investigator will undertake nanoscale imaging of trace elements distributions in these zircons together with refined isotopic measurements.This project showcases scientific and technical leadership in a field of global interest and aids in capturing the imagination of young people considering a career in science. Research outcomes are potentially of great public interest and could be akin to the results of a planetary exploration mission if the existing paradigm of Hadean Earth is overturned. Within the scientific community, evidence that the Earth was potentially habitable during the Hadean Eon would radically alter our views of the constraints on the emergence of life on this and other planets and lead genomic researchers to consider planting the roots of phylogenic trees a good deal deeper.

地球历史的前5亿年（40亿年）被称为Hadean Eon，是地球的“黑暗时代”，因为地质记录中没有超过40亿年的岩石。 但是，在年轻的石英岩岩石中发现了矿物锆石的砂晶体晶体，其历史的历史几乎与地球本身一样古老。 初步分析表明，早期地球与当今的共同点比以前想象的更多。 这个令人惊讶的结果需要详细的检查，但是Hadean Grains非常罕见，仅在一百万个沉积岩中占一部分。 遵循密集的分析计划，首席科学家和他的团队已经归档了数百个Hadean锆石，在这个项目中，他们计划进行实验，这可能使我们对地球最早的发展前所未有的见解。 要解决的问题如下：1）早期地球差异是否包括大陆壳的大量生产？ 2）类似于板块构造的机制在哈迪斯时期是否运行？ 3）为什么不存在超过40亿年的岩石？ 4）气氛何时形成？ 5）在Hadean Eon期间有海洋吗？ 6）这些古老的锆石是否存在着事物外来源？ 为了解决这些问题，研究人员将对这些锆石中的微量元素分布进行纳米级成像以及精制的同位素测量。该项目在全球兴趣领域展示了科学和技术领导力，并有助于吸引年轻人考虑从事科学职业的年轻人的想象。研究成果可能具有极大的公共利益，并且可能类似于行星勘探任务的结果，如果现有的Hadean Earth范式被推翻。 在科学界，证据表明，地球在哈迪斯·埃恩（Hadean Eon）期间潜在可居住，这从根本上改变了我们对这一行星和其他行星生命出现的约束的看法，并导致基因组研究人员考虑将系统发育的根源植根更深入。