Exploring the Hadean Earth

地球历史的前5亿年（45亿至40亿年）被称为冥古宙，是地球的“黑暗时代”，因为地质记录中没有已知的年龄超过40亿年的岩石。然而，在较年轻的石英岩中发现了沙粒大小的锆石晶体，这些石英岩的年龄几乎和地球本身一样大。初步分析表明，非常早期的地球与现在的地球有可能比以前认为的更多的共同之处。这个令人惊讶的结果需要详细的研究，但冥古宙的颗粒非常罕见，只占沉积岩的百万分之一。经过密集的分析程序，首席科学家和他的团队已经存档了几百个冥古宙的锆石，在这个项目中，他们计划进行实验，可能会让我们对地球最早的进化有前所未有的了解。需要解决的问题如下：1)早期地球分化是否包括大陆地壳的大量产生？冥古宙是否存在类似板块构造的机制？3)为什么没有年龄超过40亿年的岩石？4)大气是什么时候形成的？冥古宙时期有海洋吗？6)这些古老的锆石中有来自地外的吗？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，并进行精细同位素测量。该项目展示了全球关注领域的科学和技术领导地位，并有助于激发考虑从事科学事业的年轻人的想象力。如果现有的冥古宙地球模式被推翻，研究结果可能会引起公众的极大兴趣，类似于行星探索任务的结果。在科学界，地球在冥古宙时期可能适合居住的证据，将从根本上改变我们对地球和其他行星上生命出现的限制的看法，并促使基因组研究人员考虑把系统发生树的根埋得更深。

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.