A zircon Hf isotope data set from Archean and Paleoproterozoic magmatic and metasedimentary rocks of the southern São Francisco craton (Brazil) is interpreted as evidence of accretionary and collisional plate tectonics since at least the Archean-Proterozoic boundary. During the Phanerozoic, accretionary and collisional orogenies are considered the end members of different plate tectonic settings, both involving preexisting stable continental lithosphere and consumption of oceanic crust. However, mechanisms for the formation of continental crust during the Archean and Paleoproterozoic are still debated, with the addition of magmatic rocks to the crust being explained by different geodynamic models. Hf isotopes can be used to quantify the proportion of magmatic addition into the crust: positive εHf values are usually interpreted as indications of magmatic input from the mantle, whereas crust-derived rocks show more negative εHf. We show that the crust of the amalgamated Paleoproterozoic tectonostratigraphic terranes that make up the southern São Francisco craton were generated from different proportions of mantle and crustal isotopic reservoirs. Plate tectonic processes are implied by a consistent sequence of events involving (1) the generation of juvenile subduction-related magmatic arc rocks, followed by (2) collisional orogenesis and remelting of older crust, and (3) post-collisional bimodal magmatism.

中文翻译：

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古元古代初期地球的新构造体系：Hf 同位素证据表明巴西圣弗朗西斯科克拉通有效地壳生长和再加工

来自圣弗朗西斯科克拉通南部（巴西）的太古代和古元古代岩浆和变沉积岩的锆石 Hf 同位素数据集被解释为至少自太古代-元古代边界以来增生和碰撞板块构造的证据。在显生宙，增生和碰撞造山被认为是不同板块构造背景的末端成员，两者都涉及预先存在的稳定大陆岩石圈和大洋地壳的消耗。然而，太古宙和古元古代大陆地壳的形成机制仍然存在争议，地壳中岩浆岩的加入可以用不同的地球动力学模型来解释。Hf同位素可用于量化岩浆加入地壳的比例：正的 εHf 值通常被解释为来自地幔的岩浆输入的迹象，而地壳衍生的岩石显示出更多的负 εHf。我们表明，构成南圣弗朗西斯科克拉通的混合古元古代构造地层的地壳是由不同比例的地幔和地壳同位素储层产生的。板块构造过程由一系列一致的事件暗示，包括 (1) 年轻俯冲相关岩浆弧岩的产生，随后是 (2) 碰撞造山作用和旧地壳的重熔，以及 (3) 碰撞后双峰岩浆作用。我们表明，构成南圣弗朗西斯科克拉通的混合古元古代构造地层的地壳是由不同比例的地幔和地壳同位素储层产生的。板块构造过程由一系列一致的事件暗示，包括 (1) 年轻俯冲相关岩浆弧岩的产生，随后是 (2) 碰撞造山作用和旧地壳的重熔，以及 (3) 碰撞后双峰岩浆作用。我们表明，构成南圣弗朗西斯科克拉通的混合古元古代构造地层的地壳是由不同比例的地幔和地壳同位素储层产生的。板块构造过程由一系列一致的事件暗示，包括 (1) 年轻俯冲相关岩浆弧岩的产生，随后是 (2) 碰撞造山作用和旧地壳的重熔，以及 (3) 碰撞后双峰岩浆作用。