CHIME monazite ages of metasediments from the Altai orogen in northwestern China: Devonian and Permian ages of metamorphism and their significance
CHIME monazite ages of metasediments from the Altai orogen in northwestern China: Devonian and Permian ages of metamorphism and their significance
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DOI：
10.1111/j.1440-1738.2007.00585.x
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发表时间：
2007-12
期刊：
影响因子：
1.5
通讯作者：
Changqing Zheng;Takenori Kato;M. Enami;Xuechun Xu
中科院分区：
文献类型：
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作者：
Changqing Zheng;Takenori Kato;M. Enami;Xuechun Xu
摘要 应用化学钍铀总铅等时线法（CHIME）测定了阿尔泰造山带绿片岩-角闪岩相变沉积物中独居石颗粒的年龄。这些变质岩的分布区域根据变质年龄分为二叠纪（261~268Ma）中西部和泥盆纪（377~382Ma）东部单元。泥盆纪CHIME年龄与东部单元花岗岩体Pb-Pb年龄一致，支持花岗岩体侵位与深部区域变质作用同步的观点。先前报道的中西部单元的二叠纪变质年龄（本研究）和火成岩年龄可以用地壳物质和海洋板块的俯冲以及快速折返来解释。
Abstract The chemical Th‐U‐total Pb isochron method (CHIME) has been applied to determine the ages of monazite grains from metasediments of greenscshist‐amphibolite facies in the Altai orogen, northwest China. The area of distribution of these metamorphic rocks is divided into the Permian (261–268 Ma) central‐western and Devonian (377–382 Ma) eastern units on the basis of their metamorphic ages. The Devonian CHIME ages are consistent with the Pb–Pb ages of granitoid in the eastern unit, and support the idea that emplacement of the granitoids was synchronous with regional metamorphism at deep levels. The Permian metamorphic ages (the present study) and igneous ages previously reported from the central‐western unit can be interpreted in terms of subduction of crustal material and oceanic plate, and rapid exhumation.