Earth is the only planet known to have continents, although how they formed and evolved is unclear. Here using the oxygen isotope compositions of dated magmatic zircon, we show that the Pilbara Craton in Western Australia, Earth’s best-preserved Archaean (4.0–2.5 billion years ago (Ga)) continental remnant, was built in three stages. Stage 1 zircons (3.6–3.4 Ga) form two age clusters with one-third recording submantle δ¹⁸O, indicating crystallization from evolved magmas derived from hydrothermally altered basaltic crust like that in modern-day Iceland^1,2. Shallow melting is consistent with giant impacts that typified the first billion years of Earth history^3,4,5. Giant impacts provide a mechanism for fracturing the crust and establishing prolonged hydrothermal alteration by interaction with the globally extensive ocean^6,7,8. A giant impact at around 3.6 Ga, coeval with the oldest low-δ¹⁸O zircon, would have triggered massive mantle melting to produce a thick mafic–ultramafic nucleus^9,10. A second low-δ¹⁸O zircon cluster at around 3.4 Ga is contemporaneous with spherule beds that provide the oldest material evidence for giant impacts on Earth¹¹. Stage 2 (3.4–3.0 Ga) zircons mostly have mantle-like δ¹⁸O and crystallized from parental magmas formed near the base of the evolving continental nucleus¹². Stage 3 (<3.0 Ga) zircons have above-mantle δ¹⁸O, indicating efficient recycling of supracrustal rocks. That the oldest felsic rocks formed at 3.9–3.5 Ga (ref. ¹³), towards the end of the so-called late heavy bombardment⁴, is not a coincidence.

地球是已知的唯一拥有大陆的行星，尽管它们是如何形成和演化的尚不清楚。在这里，我们使用已测定年代的岩浆锆石的氧同位素组成，表明西澳大利亚的皮尔巴拉克拉通是地球上保存最完好的太古代（4.0-25 亿年前 (Ga)）大陆遗迹，分三个阶段形成。第 1 阶段锆石 (3.6–3.4 Ga) 形成两个年龄群，其中三分之一记录地幔 δ ¹⁸ O，表明从热液蚀变玄武岩地壳衍生的演化岩浆结晶，就像现代冰岛^1,2一样。浅层融化与代表地球历史第一个十亿年的巨大撞击相一致^3,4,5. 巨大的撞击提供了一种机制，可以使地壳破裂并通过与全球广阔的海洋^6,7,8的相互作用建立长期的热液蚀变。与最古老的低 δ ¹⁸ O 锆石同时代的 3.6 Ga 左右的巨大撞击会引发大量地幔熔化，从而产生厚实的基性-超基性核^9,10。第二个低 δ ¹⁸ O 锆石簇位于 3.4 Ga 左右，与球粒床同时存在，为地球上的巨大撞击提供了最古老的物质证据¹¹。第 2 阶段 (3.4–3.0 Ga) 锆石大多具有类似地幔的 δ ¹⁸ O，由演化大陆核底部附近形成的母岩浆结晶¹². 第 3 阶段 (<3.0 Ga) 锆石具有上地幔 δ ¹⁸ O，表明表壳岩石的有效再循环。最古老的长英质岩石形成于 3.9-3.5 Ga（参考文献¹³），接近所谓的晚期重轰击⁴的末尾，这并非巧合。