Centre for Exploration Targeting, Australian Research Council Centre of Excellence for Core to Crust Fluid Systems, School of Earth and Environment, University of Western Australia, Perth, WA 6009, Australia;Department of Applied Geology, Curtin University, Bentley, WA 6102, Australia;
Centre for Exploration Targeting, Australian Research Council Centre of Excellence for Core to Crust Fluid Systems, School of Earth and Environment, University of Western Australia, Perth, WA 6009, Australia;
Proc Natl Acad Sci U S A. 2014 Jul 15;111(28):10083-8. doi: 10.1073/pnas.1400273111. Epub 2014 Jun 23.
The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.
地球大陆地壳的形成和演化在行星的发展中起着至关重要的作用。它的形成改变了地幔的组成，有助于大气的建立，并导致了对早期生命至关重要的生态位的形成。在这里，我们表明，在太古代，大陆的形成和稳定也控制了地球上保存最完好的熔岩——科马提岩的位置、地球化学和火山学特征：这些岩浆通常代表地幔 50-30%的部分熔融，并随后记录了太古宙-元古代地球热和化学演化的重要信息。因此，限制和理解控制它们定位和就位的过程至关重要。在这里，我们结合 Lu-Hf 同位素和 U-Pb 年代学，绘制了西澳大利亚伊尔岗克拉通的四维演化图，揭示了太古宙微大陆的渐进发展。我们的结果表明，在早期地球上，相对较小的地壳块体，类似于现代微板块，逐渐合并形成更大的大陆块体，并最终形成第一批克拉通。这个克拉通化过程将最炽热和最大量的科马提岩喷发驱动到已建立的大陆块体的边缘。因此，早期大陆的动态演化直接影响了深部地幔物质向太古宙地壳、海洋和大气的添加，同时也对主要岩浆矿床的分布提供了基本控制。
