华南地块雪峰山中生代板内造山带构造样式及其形成机制  

Structural style and kinematics of the Mesozoic Xuefengshan intraplate orogenic belt

作　　者：颜丹平[1,2] 邱亮[1] 陈峰[1] 李林[1] 赵磊[1] 杨文心 张翼西[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083

出　　处：《地学前缘》2018年第1期1-13,共13页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2014CB440903);国家自然科学基金项目(41372212;41672216)

摘　　要：华南大地构造核心问题之一是江南—雪峰山造山带的属性。在前人工作基础上,对横切雪峰山造山带的地质剖面进行了详细的区域地质、构造变形和部分重点区段地震反射剖面深部构造解释,划分出5个大地构造单元:(1)湘中复合逆冲构造带。该带位处雪峰山造山带东部,以龙山复合构造穹隆等为代表,是近EW向加里东造山带与NE向燕山造山带复合叠加的结果;其中燕山期构造样式总体为倾向SE逆冲断层控制的尖棱背斜构造。(2)雪峰山厚皮逆冲构造带。该带西以大庸逆冲断裂为界,带内板溪群浅变质褶皱基底大面积出露,总体发育指向NW的断层-褶皱组合。断坪-断坡式逆冲断层从板溪群内部薄弱层发育,向浅部产状明显变陡,并导致新元古界板溪群逆冲于古生界之上,控制了沅麻等中生代盆地的形成,沿断坡形成紧闭背斜和沿断坪形成宽缓向斜;表明其为典型的断层相关褶皱。断层褶皱组合与地表剥蚀共同作用,形成飞来峰和构造窗。(3)以梵净山构造穹隆为代表的梵净山—走马构造穹隆带。该带呈NE向长垣状,核部出露新元古界下部梵净山群。断坪-断坡式逆冲断层深切梵净山群,在断层上盘形成不对称箱状背斜。因此总体为典型的厚皮逆冲作用下的断层相关褶皱。(4)隔槽式逆冲构造带。此带主要发育一系列轴向NE的箱状背斜和尖棱向斜。箱状背斜核部为寒武系,向深部卷入震旦系—板溪群,形成基底卷入的断层-褶皱组合,其浅部形成叠瓦状逆冲断层-褶皱组合,从而构成主动双重逆冲构造。(5)华蓥山断裂与齐岳山断裂间的隔档式薄皮构造带。带内以发育尖棱背斜和箱状向斜为特征,是倾向SE断坪-断坡控制下的断展褶皱组合。上述5个构造单元变形区域卷入了上三叠统—下侏罗统,但为上白垩统角度不整合覆盖,表明变形时间为中生代中晚期,并且有从SE向NW渐次变新的One of the key scientific issues related to tectonics of the South China Block focuses on the nature of the JiangnanXuefeng orogenic belt. In this study, structural style and kinematics of five tectonic units, namely the Xiangzhong composite thrust belt, Xuefengshan thickskinned thrust belt, FanjingshanZouma domal belt, troughlike faultfold thrust belt and ejective thinskinned thrust belt, are identified along a geological crosssection of the Xuefeng orogenic belt with detailed profiles of regional geology, deformation and seismic interpretation. Our study shows： （1） The Xiangzhong composite thrust belt in the eastern Xuefeng orogenic belt is represented by the Longshan composite tectonic dome. This dome has structural style of the SEdipping thrust faultrelated Mesozoic chevron anticline, which overprinted the EWstriking Caledonian anticline. （2） The Xuefengshan thickskinned thrust belt is bordered by the Dayong thrust fault to the west, and outcrops extensively the shallow metamorphic Banxi Group. This belt has the NW faultrelated folds with smaller slip flatramp fault, where flat developed along the weak layers within the Banxi group while ramp cuts upward, thus producing the broad syncline and tight anticline, respectively. The flatramp fault also resulted in the Neoproterozoic Banxi Group thrusting over the Paleozoic, and the formation of the Yuanma Basin and klippes and tectonic windows. （3） The FanjingshanZouma domal belt is represented by the Fanjingshan tectonic dome. This dome has the structural style of faultrelated fold, with SEdipping flatramp thrust fault and hangingwall anisomerous box anticline, which outcrops the early Neoproterozoic Fanjingshan Group in the core. Thus the Fanjingshan tectonic dome was produced by thickskinned thrust. （4） The troughlike faultfold thrust belt contains a series of NEstriking parallel box anticlines and chevron synclines. The Cambrian outcrops in the core of the box anticlines whil

关 键 词：雪峰山 中生代板内造山带 断层相关褶皱 穹隆状构造 运动学模式 

分 类 号：P542[天文地球—构造地质学]