Li Jun-Yong, Tang Ming, Lee Cin-Ty A, Wang Xiao-Lei, Gu Zhi-Dong, Xia Xiao-Ping, Wang Di, Du De-Hong, Li Lin-Sen
State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.
Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA.
Nat Commun. 2021 Jun 10;12(1):3533. doi: 10.1038/s41467-021-23797-3.
In subduction zones, materials on Earth's surface can be transported to the deep crust or mantle, but the exact mechanisms and the nature of the recycled materials are not fully understood. Here, we report a set of migmatites from western Yangtze Block, China. These migmatites have similar bulk compositions as forearc sediments. Zircon age distributions and Hf-O isotopes indicate that the precursors of the sediments were predominantly derived from juvenile arc crust itself. Using phase equilibria modeling, we show that the sediments experienced high temperature-to-pressure ratio metamorphism and were most likely transported to deep arc crust by intracrustal thrust faults. By dating the magmatic zircon cores and overgrowth rims, we find that the entire rock cycle, from arc magmatism, to weathering at the surface, then to burial and remelting in the deep crust, took place within ~10 Myr. Our findings highlight thrust faults as an efficient recycling channel in compressional arcs and endogenic recycling as an important mechanism driving internal redistribution and differentiation of arc crust.
在俯冲带，地球表面的物质可被输送到地壳深部或地幔，但具体机制以及再循环物质的性质尚未完全明晰。在此，我们报道了一组来自中国扬子地块西部的混合岩。这些混合岩的总体成分与弧前沉积物相似。锆石年龄分布和铪 - 氧同位素表明，沉积物的前体主要源自新生弧地壳本身。通过相平衡模拟，我们发现这些沉积物经历了高温 - 高压比变质作用，且极有可能是通过地壳内逆冲断层被输送到深部弧地壳。通过对岩浆锆石核部和增生边进行年代测定，我们发现整个岩石循环，从弧岩浆作用，到地表风化，再到深部地壳中的埋藏和重熔，在约1000万年的时间内完成。我们的研究结果突出了逆冲断层作为挤压弧中一种高效再循环通道的作用，以及内生成因再循环作为驱动弧地壳内部重新分配和分异的重要机制。
