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引用本文:柏道远 熊雄 杨俊 钟响 贾朋远 黄文义. 雪峰造山带中段地质构造特征[J]. 中国地质, 2014, 41(2): 399-418.
Bai Daoyuan, Xiong Xiong, Yang Jun, Zhong Xiang, Jia Pengyuan, Huang Wenyi. Geological structure characteristics of the middle segment of the Xuefeng orogen[J]. Geology in China, 2014, 41(2): 399-418(in Chinese with English abstract).
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雪峰造山带中段地质构造特征
柏道远 熊雄 杨俊 钟响 贾朋远 黄文义
湖南省地质调查院,湖南长沙410016
摘要:
雪峰造山带的地质构造特征认识尚存在较多分歧。通过构造剖面测制并结合区域地质调查,对雪峰造山带中段东部怀化—两丫坪地区的形变类型、变形时代、变形强度、剖面结构以及构造变形的运动学特征、成因机制和构造体制等进行了较全面的分析研究,取得以下主要认识和进展:(1)雪峰造山带中段形变类型主要有板劈理、折劈理、褶皱及与褶皱同走向的大型膝褶带、逆断裂、正断裂、右行走滑断裂等;(2)加里东运动和早中生代构造运动(印支运动与早燕山运动)中均存在明显的挤压变形,构造体制均为NW—NWW向挤压,形成NE—NNE向褶皱和逆断裂,加里东运动尚形成了板劈理和大型膝褶带;(3)雪峰造山带中段以溆浦—靖州断裂为界分为东带和西带,分别为加里东期区域雪峰逆冲推覆构造的根带和中带。东带板劈理发育,西带板劈理不发育且上古生界与下伏地层产状相近,表明加里东运动中东带变形强度明显大于西带,不整合特征、抬升幅度、逆冲断裂的发育特征等表明早中生代构造运动中东带变形较强,而西带变形较弱;(4)劈理优势倾向以及褶皱轴面和逆断裂的倾向,反映雪峰造山带东带加里东运动和早中生代构造运动中均具有背冲构造样式,但早中生代背冲构造的中轴相对加里东期向西迁移25 km以上;(5)南华纪早期溆浦—靖州断裂以东大幅伸展断陷并接受巨厚沉积,晚古生代期间断裂东侧大幅伸展沉降而构成湘中沉积盆地的西边界,反映雪峰造山带东带为一块体强度低的构造薄弱带,这是其变形强度大于西带及成为雪峰推覆构造根带的主要原因。
关键词:  雪峰造山带中段  加里东运动  早中生代构造运动  NW—NWW向挤压  溆浦—靖州断裂  构造分带  背冲构造
DOI:
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基金项目:中国地质调查局项目(1212011120793、1212010811032、1212011220750-02)联合资助。
Geological structure characteristics of the middle segment of the Xuefeng orogen
Bai Daoyuan, Xiong Xiong, Yang Jun, Zhong Xiang, Jia Pengyuan, Huang Wenyi
Hunan Institute of Geological Survey, Changsha 410016, Hunan, China
Abstract:
There exist different view points about the geological structure characteristics of the Xuefeng orogen. The authors studied such aspects of this problem as deformation types, deformation epochs and intensities, geometrical and kinematic properties, dynamic mechanisms and tectonic regimes in Huaihua- Liangyaping area lying in the eastern part of the middle segment of the Xuefeng orogen through tectonic profile and regional geological survey and, as a result, reached the following conclusions: ①There existed main deformation types such as slaty cleavages, crenulation cleavages, folds, thrust faults, large-scale kink zones, normal faults and dextral strike-slip faults. ②There existed notable compressional deformations with NW to NWW compression and NE to NNE-trending folds and thrust faults in both Caledonian movement and Early Mesozoic tectonic movements (Indosinian movement and Early Yanshanian movement). Slaty cleavages and large-scale kink zones were formed in Caledonian movement. ③The middle segment of the Xuefeng orogen can be divided into the east zone and the west zone with Xupu- Jingzhou fault as the boundary, which served as the root and the middle zone of Xuefeng thrust system respectively. There existed higher deformation in the east zone than in the west zone in Caledonian movement, as evidenced by the existence of slaty cleavages in the east zone and the absence of slaty cleavage and the similarity between the Upper Palaeozoic and the underlying strata in attitude in the west zone. Unconformity, tectonic uplift and thrust faults indicate that there existed stronger deformation in the east zone than in the west zone in Early Mesozoic tectonic movement. ④Dip directions of slaty cleavages, fold axial surfaces and thrust faults indicate that there existed back- thrust structures in both Caledonian movement and Early Mesozoic tectonic movements in the east zone of the Xuefeng orogen, but the middle belts of the two period back thrust structures didn't coincide with each other, and the middle belt in Early Mesozoic was about 25km west of Caledonian. ⑤ The east side of Xupu- Jingzhou fault subsided violently in both early Nanhuan and Late Palaeozoic, suggesting that the east zone of the Xuefeng orogen was a structurally weak zone with lower strength of crust, and therefore turned into the root zone of the Xuefeng thrust system.
Key words:  middle segment of the Xuefeng orogen  Caledonian movement  Early Mesozoic tectonic movement  NW to NWW compression  Xupu-Jingzhou fault  structural zone  back thrust structures