Abstract The continental crust grows via juvenile additions from the mantle. However, the timing of initial continent stabilisation and the rate of subsequent continental growth during the first billion years of Earth history is widely debated, in part due to uncertainty over the composition of the mantle source of new crust. Well-preserved Archean granite-greenstone terranes, as present within the Pilbara Craton (Western Australia), provide insights into the sources of felsic magmas and the processes of continental growth and evolution in the distant geological past at the regional scale. Here, we present zircon U-Pb, O and Hf isotope data from ancient gneissic and granitic rocks of the Pilbara Craton, to decipher magma sources and the timing and processes of craton growth. There is no evidence for depleted mantle compositions, and the simplest interpretation is that the crust of the Pilbara Craton was generated from mantle with a chondritic Hf isotope composition. Our results indicate crustal addition at ~3.59 Ga, represented by emplacement of gabbroic to anorthositic rocks. We suggest that the formation of these igneous rocks, and the foundering of the complementary residues, triggered extensive melting of hot, upwelling mantle, leading to the subsequent accumulation of the >12 km thick greenstone belt eruptive sequences from 3.53 Ga, with emplacement of coeval felsic magmas at depth. This process shaped the initial crustal configuration of the proto-craton, which subsequently underwent gravitationally driven overturn and reworking to generate stable, cratonic continental crust with the distinctive dome and keel architecture. The zircon Hf and O isotope signatures of the Pilbara igneous rocks from ~3.59–3.4 Ga do not support remelting of an ancient (> 3.8 Ga) basement, and reinforce the overwhelmingly chondritic to near-chondritic zircon Hf isotope composition of Eoarchean meta-igneous rocks from a number of different Archean cratons. A corollary of this remarkable global consistency is that a significant volume of the mantle maintained a chondritic composition for the Lu-Hf system from the formation of the Earth into the Paleoarchean (up to 3.6–3.5 Ga), as would be the case if stabilised volumes of felsic continental crust prior to 3.5 Ga were relatively small. One implication is that the common assumption of a linear evolution of depleted mantle from 4.5 Ga to the present day is inappropriate for determining the timing and volume of continental crust extraction in the Archean. The nearly identical early evolution of the Pilbara and Kaapvaal cratons suggests a common process to generate Archean granite-greenstone terranes that does not require extensive reworking of ancient crust, but rather involves juvenile crustal addition above persistent zones of upwelling, chondritic mantle.

中文翻译：

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从全球球粒状地幔形成早期太古代花岗岩-绿岩地体：来自西澳大利亚皮尔巴拉克拉通火成岩的见解

摘要 大陆地壳是通过地幔中的幼年添加物生长的。然而，在地球历史的最初 10 亿年期间，最初大陆稳定的时间和随后大陆增长的速度引起了广泛的争论，部分原因是新地壳的地幔源组成的不确定性。皮尔巴拉克拉通（西澳大利亚）中保存完好的太古代花岗岩-绿岩地体提供了对长英质岩浆来源以及区域尺度上遥远地质过去大陆生长和演化过程的深入了解。在这里，我们提供了皮尔巴拉克拉通古老片麻岩和花岗岩的锆石 U-Pb、O 和 Hf 同位素数据，以破译岩浆来源以及克拉通生长的时间和过程。没有证据表明地幔成分已耗尽，最简单的解释是皮尔巴拉克拉通的地壳是由具有球粒陨石 Hf 同位素组成的地幔形成的。我们的结果表明地壳添加在~3.59 Ga，表现为辉长岩对斜长岩的侵位。我们认为，这些火成岩的形成和互补残留物的沉没，引发了热的上涌地幔的广泛熔化，导致随后积累了 3.53 Ga 的 > 12 公里厚的绿岩带喷发序列，同时深部长英质岩浆。这一过程塑造了原克拉通的初始地壳构造，随后在重力驱动下经历了翻转和改造，形成了具有独特圆顶和龙骨结构的稳定的克拉通大陆地壳。来自~3.59-3.4 Ga 的皮尔巴拉火成岩的锆石 Hf 和 O 同位素特征不支持古老（> 3.8 Ga）基底的重熔，并加强了始太古代变火成岩的绝大多数球粒状至近球粒状锆石 Hf 同位素组成来自许多不同太古代克拉通的岩石。这种显着的全球一致性的一个推论是，从地球形成到古太古代（高达 3.6-3.5 Ga），大量地幔保持了 Lu-Hf 系统的球粒陨石成分，如果稳定下来就会如此3.5 Ga 之前的长英质大陆地壳的体积相对较小。一个含义是从 ​​4 开始的耗尽地幔线性演化的共同假设。5 Ga 至今不适合确定太古代大陆地壳提取的时间和体积。Pilbara 和 Kaapvaal 克拉通的早期演化几乎完全相同，这表明产生太古代花岗岩-绿岩地体的共同过程不需要对古代地壳进行广泛的改造，而是涉及在上涌的球粒状地幔的持续区域上方添加幼年地壳。