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歙县—祁门断裂带南北两侧新元古代基底变质—变形差异及成因探讨
投稿时间:2018-01-15  修订日期:2018-07-28  点此下载全文
引用本文:胡军,余心起,曾严,刘孟言,刘秀,汪子莘.2018.歙县—祁门断裂带南北两侧新元古代基底变质—变形差异及成因探讨[J].地质论评,64(6):1339-1355,[DOI]:.
HU Jun,YU Xinqi,ZENG Yan,LIU Mengyan,LIU Xiu,WANG Zishen.2018.Metamorphic—Deformation Difference of Neoproterozoic Basements between North and South Sides of the Shexian—Qimen Fault Belt and a Discusion on Its Genesis[J].Geological Review,64(6):1339-1355.
DOI:
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作者单位E-mail
胡军 中国地质大学(北京)地球科学与资源学院北京100083 18600213330@163.com 
余心起 中国地质大学(北京)地球科学与资源学院北京100083 yuxinqi@cugb.edu.cn 
曾严 中国地质大学(北京)地球科学与资源学院北京100083  
刘孟言 中国地质大学(北京)地球科学与资源学院北京100083  
刘秀 中国地质大学(北京)地球科学与资源学院北京100083  
汪子莘 中国地质大学(北京)地球科学与资源学院北京100083  
基金项目:本文为国家自然科学基金资助项目“大陆中部地壳天然固态流变与应变局部化”(编号:41430211)和“皖浙赣相邻区中生代推(滑)覆构造特征及其时序分析”(编号:41872201)的成果。
中文摘要:已有的研究对皖浙赣相邻区新元古代基底岩系中上溪群和历口群的相互叠置关系和内部层序认识上存在一定的分歧,同时野外地质现象和前人研究成果均表明了以歙县—祁门断裂带为界南北两侧基底岩系存在明显的变质变形差异。本文通过野外典型剖面及关键地区地质现象的观测,即歙县三阳坑倒转不整合和呈坎镇上汪村牛屋组与许村岩体之间的侵入关系,结合已有年龄数据分析,认为历口群应置于上溪群之上,牛屋组为该套基底岩系最底层;通过洽舍—寨西、虹关—板桥—溪口剖面和其他地点野外地质现象观察,结合部分岩相学的分析和已有资料,表明歙县—祁门断裂带北部以牛屋组为底,以上岩系表现为未变质或浅变质弱变形成层有序,南部则以井潭组为顶层,以下岩系表现为中等变质强变形片状无序。据已有的变形年龄,这种差异性变质变形主要是加里东构造事件的产物;造成这种现象的主要原因是:加里东期在江南造山带东段东南缘发生的陆内造山作用使得江山—绍兴断裂带北西发生了区域性动力变质及相应的变形,而歙县—祁门断裂带使由南往北的应力在南部岩系沿该断裂带向北逆冲的过程中得到了一定的削减释放,同时使较深部经受脆韧性变形和弱变质的岩层隆升遭受剥蚀,综合作用导致断裂带北侧较南侧处于一个弱变形环境,从而形成区域上的这种差异性变质变形。
中文关键词:皖浙赣相邻区  江南造山带  新元古代  歙县—祁门断裂带
 
Metamorphic—Deformation Difference of Neoproterozoic Basements between North and South Sides of the Shexian—Qimen Fault Belt and a Discusion on Its Genesis
NameInstitution
HU JunSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
YU XinqiSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
ZENG YanSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
LIU MengyanSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
LIU XiuSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
WANG ZishenSchool of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing, 100083
Abstract:Objectives: The previous researches have different recognitions and debates in understanding the interposition relationship and internal sequences of the Shangxi Group and the Likou Group within the Neoproterozoic basement from the adjacent area among Anhui—Zhejiang—Jiangxi Provinces. The field geological phenomenas and former study results show that there is a significant difference in metamorphic and deformation characteristics of the Neoproterozoic basements between the north and south sides of the Shexian—Qimen fault. Methods: By observing the sequence sections and key spots like reverse unconformable interface between the Nanhua and Neoproterozoic basement from Sanyang Town, Shexian County, and the intrusion relation between the Shangxi group and the Xucun pluton from Chenkan Town, as well as combining with the published age data, this paper believed that the lowest bed of the Neoproterozoic basement is the Niuwu Formation, the Likou group should be placed above the Shangxi group. Results: The field geological phenomenas from Qiashe—Zhaixi section, Hongguan—Banqiao—Xikou section and other scattered points, associated with some petrographic analysis and existing data, show that the upper and lower strata of the Neoproterozoic basements in the north of the fault zone are not metamorphic or shallow metamorphic (belongs to stratified and ordered rock series). But in the south, the Neoproterozoic strata are characterized by medium metamorphic and strong deformation (belongs to flaky and disordered rock series). Conclusins: This deformation occurred during the Caledonian tectonic events according to the published deformation ages. Caledonian tectonic event caused the difference of the metamorphic and deformation characteristics of the Neoproterozoic basements between the north and south sides in the adjacent region among Anhui, Zhejiang, and Jiangxi Provinces. The reason was that the Caledonian orogenic event in the south China had extended and resulted in regional metamorphism and corresponding deformation in the northwest of Jiangshan—Shaoxing orogenic belt. However, the dynamical stress was weakened in the north of the Shexian—Qimen fault zone because of the northward thrust along the Shexian—Qimen fault zone and uprising—erosion in the south, which leading to the weak deformation environment in the north side of the Shexian—Qimen fault zone than that of the south.
keywords:Anhui—Zhejiang—Jiangxi adjacent region  Jiangnan orogen  Neoproterozoic  Shexian—Qimen fault zone
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