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日前,地质学家在西澳大利亚杰克·希尔(Jack Hills)地区的砂岩层中发现了一种极为古老的锆石晶体。通过铀—铅同位素测年发现,这些锆石晶体形成于44亿年之前。这表明,在地球形成的2亿年之后便逐渐拥有了固体地壳。而这一时间比原先预计的要早了很多。此前,人们一直认为,地球形成后不久即与一个火星大小的天体发生了剧烈碰撞,月球的胚胎由此产生。而在此之前,地球则更像是一个熔融的岩浆球。
Recently, geologists discovered an extremely ancient zircon crystal in sandstone formations in the Jack Hills area of Western Australia. Uranium-lead isotope dating found that these zircon crystals formed 4.4 billion years ago. This shows that there is gradually a solid crust after 200 million years of Earth’s formation. This time is much earlier than originally expected. Previously, people had always believed that the Earth’s embryo was generated by a violent collision with a Mars-sized object shortly after Earth’s formation. Before that, the earth was more like a molten magma ball.