Geochronological Constraints on the Origin of the Paleoproterozoic Qianlishan Gneiss Domes in the Khondalite Belt of the North China Craton and Their Tectonic implications
Geochronological Constraints on the Origin of the Paleoproterozoic Qianlishan Gneiss Domes in the Khondalite Belt of the North China Craton and Their Tectonic implications
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DOI：
10.3390/min13111361
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发表时间：
2023-10
期刊：
影响因子：
2.5
通讯作者：
Hengzhong Qiao;Peipei Deng;Jiawei Li
中科院分区：
文献类型：
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作者：
Hengzhong Qiao;Peipei Deng;Jiawei Li
古元古代片麻岩穹窿是华北克拉通西北部孔雀岩带的重要构造。然而，对它们的形成和演化的关注较少，从而阻碍了对孔雀石带变形史的更好理解。本文对孔雀岩带千骊山片麻岩穹丘进行了构造和年代学研究。野外观测和锆石U-Pb定年结果表明，千里山片麻岩穹隆的核心为2.06 ~ 2.01 Ga花岗类岩体，外围为千里山群麻粒岩相变质沉积岩（孔大理岩）。两者均经历了晚古元古代D1-D2两大变形期。其中，在~1.95 Ga， D1变形主要产生倒转-平卧等斜褶皱F1和穿透转置片理/片理S1。随后，D2变形在1.93 ~ 1.90 Ga形成NW(W)—se (E)向双陡陷直立褶皱F2，具有强烈的S1重定向片麻岩质，形成千里山片麻岩丘。结合前人研究，认为千里山片麻质穹窿是阴山地块与鄂尔多斯地块古元古代碰撞造山作用的产物。此外，双俯冲反形体的发育被认为是孔雀岩带形成穹隆的重要机制。
The Paleoproterozoic gneiss domes are important structures of the Khondalite Belt in the northwestern North China Craton. However, less attention has been paid to their formation and evolution, and it thus hampers a better understanding of the deformation history of the Khondalite Belt. In this paper, we conducted structural and geochronological studies on the Qianlishan gneiss domes of the Khondalite Belt. The field observations and zircon U–Pb dating results show that the Qianlishan gneiss domes consist of 2.06–2.01 Ga granitoid plutons in the core, rimmed by granulite facies metasedimentary rocks (khondalites) of the Qianlishan Group. Both of them were subjected to two major phases of deformation (D1–D2) in the late Paleoproterozoic. Of these, D1 deformation mainly generated overturned to recumbent isoclinal folds F1 and penetrative transposed foliations/gneissosities S1 at ~1.95 Ga. Subsequently, D2 deformation produced the NW(W)–SE(E)-trending doubly plunging upright folds F2 at 1.93–1.90 Ga, and they have strongly re-oriented S1 gneissosities, giving rise to the Qianlishan gneiss domes. Combined with previous studies, we argue that the Qianlishan gneiss domes were the products of the Paleoproterozoic collisional orogenesis between the Yinshan and Ordos Blocks. Additionally, the development of doubly plunging antiforms is considered an important dome-forming mechanism in the Khondalite Belt.