| 东南极拉斯曼丘陵地区变质杂岩的层序与构造变形过程 |
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| 引用本文： | 胡健民,王伟,赵越,刘晓春,陈虹,董晓朋.东南极拉斯曼丘陵地区变质杂岩的层序与构造变形过程[J].地质力学学报,2021,27(5):719-735. |
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| 作者姓名： | 胡健民 王伟 赵越 刘晓春 陈虹 董晓朋 |
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| 作者单位： | 1.中国地质科学院地质力学研究所, 北京 100081 |
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| 基金项目： | 国家自然科学基金项目（41530209，41941004，40872135）；中国地质调查局地质调查项目（1212010711509，DD20160060） |
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| 摘 要： | 东南极拉斯曼丘陵地区位于兰伯特裂谷东缘普里兹湾东岸，该地区主要出露一套麻粒岩相变质岩，前期对原岩时代、变质过程等进行了详细研究，但是对于变质杂岩的层序和变形过程研究相对薄弱。文章通过大比例尺地质填图，发现拉斯曼丘陵地区变质杂岩总体成层有序，在此基础上建立拉斯曼岩群，并将其划分成6个岩组，原岩形成时代为中元古代。拉斯曼岩群经历了格林维尔期和泛非期变质作用的叠加，变质程度均达到高角闪岩相-麻粒岩相。拉斯曼丘陵地区主体构造线方向为北东东—南西西方向，总体上构成往北东东方向翘起的复式向斜构造，几个岩组的分布也显示由东向西逐渐变新。东部米洛半岛一带明显叠加了北北西—南南东向的构造变形。研究表明，拉斯曼岩群经历了6次重要的构造变形，包括新元古代格林维尔期(D1)、新元古代—早古生代泛非期变质变形作用(D2，D3，D4，D5)以及中新生代伸展作用(D6)。目前岩石中保存的主变形面理是格林维尔期和泛非期两次构造热事件的复合型面理，主要是泛非事件形成，格林维尔期变形面理呈残留状。综合拉斯曼岩群变质年龄及早古生代进步花岗岩体形成时代，认为D2~D5变形时代为550~500 Ma左右。因此，拉斯曼丘陵地区变质变形特征显示，中元古代拉斯曼岩群经历了格林维尔期和泛非期两次重要的造山作用，以及冈瓦纳大陆的裂解。
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| 关 键 词： | 东南极 拉斯曼丘陵 拉斯曼岩群 构造变形 构造格架 |
| 收稿时间： | 2021/8/30 0:00:00 |
| 修稿时间： | 2021/9/22 0:00:00 |
Sequence and tectonic deformation process of metamorphic complex in the Larsemann Hills, East Antarctica |
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| HU Jianmin,WANG Wei,ZHAO Yue,LIU Xiaochun,CHEN Hong,DONG Xiaopeng.Sequence and tectonic deformation process of metamorphic complex in the Larsemann Hills, East Antarctica[J].Journal of Geomechanics,2021,27(5):719-735. |
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| Authors: | HU Jianmin WANG Wei ZHAO Yue LIU Xiaochun CHEN Hong DONG Xiaopeng |
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| Institution: | 1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China2.Research Center for Polar Geosciences, China Geological Survey, Beijing 100081, China3.Key Laboratory of Paleomagnetism and Tectonic Reconstruction of Ministry of Natural Resources, Beijing 100081, China |
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| Abstract: | The Larsemann Hills are located on the eastern coast of the Prydz Bay in East Antarctica. Based on large-scale geological mapping, metamorphic complex in the Larsemann Hills was found to be layered orderly in general, and therefore, the Larsemann Group is established. The Larsemann Group is subdivided into 6 rock formations, and the protolith formation age is the Mesoproterozoic. The group has experienced the superposition of the Grenvillian and Pan-African metamorphism, and the metamorphic grade reached upper amphibolite facies to granulite facies. The main structural line in the Larsemann Hills is in the NEE-SWW strain, which generally constitutes a synclinorum structure verging to NEE. The distribution of several rock formations also shows the gradually younging from east to west. The NNW-SSE deformation of the structural line is obviously superimposed on the eastern Mirror Peninsula. The study shows that the Larsemann Group has suffered 6 periods of deformation, including the early Neoproterozoic Grenvillian period (D1), the late Neoproterozoic to early Paleozoic Pan-African periods (D2, D3, D4 and D5) and the Meso-Cenozoic extension (D6). The foliations presented in the rocks are actually the composite foliations of both the Grenvillian and Pan-African events, and the Pan-African event is demonstrated stronger than the Grenvillian event, which is rarely preserved in the gneisses. Constrained with both the metamorphic age of the Larsemann Group and the intrusion time of the Progress granite, it is believed that the D2~D5 deformations occurred during the span of 550~500 Ma. Thus, both the metamorphism and deformation features of rocks from the Larsemann Hills show that the Mesoproterozoic Larsemann Group have witnessed two orogenies of Grenvillian and Pan-African periods, respectively, and the breakup of the Gondwana. |
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| Keywords: | East Antarctica Larsemann Hills Larsemann Group tectonic deformation tectonic framework |
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