摘要
秭归褶皱带位于大巴山逆冲带与雪峰山逆冲带叠合部位,总体呈现穹窿-盆地型式,是构造复合、联合作用的结果,记录了大巴山逆冲带与雪峰山逆冲带两者相互作用的重要信息,是研究构造复合和联合过程的理想区域。本文通过对秭归褶皱带秭归向斜、巴东复向斜和香龙山背斜的野外调查,对褶皱枢纽、相关断层、节理等进行详细构造解析,理清了先后叠加关系,在此基础上进行了构造分期和配套,对变形期古构造应力场进行了恢复重建。结果表明秭归褶皱带晚侏罗世-早白垩世经历三期构造变形:D1期以近EW向的秭归向斜和香龙山背斜为代表,秭归向斜为轴面近直立的开阔圆弧状,香龙山背斜呈轴面近直立的箱状,相关逆冲断层具由北向南逆冲的特点,可能与大巴山由NE向SW逆冲作用有关。D2期秭归向斜叠加近SN向枢纽,呈锅状,香龙山背斜东段发育鼻状的五龙背斜,褶皱带呈穹窿-盆地型。与向斜相关的水田坝断裂带向SEE逆冲,主压应力场呈NWW-SEE近平行的束状。该期变形可能与雪峰山逆冲带向NW逆冲过程中受到黄陵背斜阻挡有关。D3期秭归向斜近SN向枢纽向南西弯曲,巴东复向斜呈NW凸出弧形,香龙山背斜西端叠加NE-SW向构造形迹。主压应力场总体向NW发散。该期变形可能与雪峰山逆冲带向NW逆冲推挤有关。上述构造分析表明,向SW逆冲的大巴山逆冲带先影响鄂西地区,之后向NW逆冲推挤的雪峰山逆冲带扩展至该地区,形成复合关系。区域构造与地层关系分析表明D1-D3形成于J3-K1,因此秭归褶皱带是大巴山逆冲构造带向SW叠瓦逆冲并与指向NW的雪峰山逆冲带复合叠加的结果,表明上扬子地区在J3-K1经历了分阶段复合叠加的过程,即前期受到大巴山逆冲带近SN构造作用影响,后期经历向NW逆冲推挤的雪峰山逆冲带NW-SE向构造叠加。
Zigui fold belt is located in the congruent part of Dabashan and Xuefengshan thrust belt,which is dome and basin,and is the result of the tectonic compounding and combination.Because Zigui fold belt recorded the important imformation reflecting the interaction of Dabashan and Xuefengshan thrust belt,it is the ideal site of studying on the compounding and combination process.This paper has a field research on Zigui sycline,Badong synclinorium and Xianglongshan anticline in Zigui fold belt,whose hinge of fold,fold related fault and joints are been structural analysis in detail,then we determine the superposition relation among them.Based on those,we distinguished different deformation through matching by stages,then reconstruct the paleo-stress-field during deformation stage.The result shows that Zigui fold belt experienced three stage deformation during J3-K1：D1 is that the Zigui sycline and Xianglongshan anticline was nearly EW.Zigui sycline was extensive round with the nearly upright axe and Xianglongshan anticlne was box with the upright axe.The related thrust fault was characteristic by thrusting from north to south. Those features may be related to Dabashan thrusting from NE to SW.D2 is that Zigui sycline was superposition with hinge of nearly SN,then the sycline showed like a pan and the Wulong anticline developed in the east of Xianglongshan anticline.The fold belt was dome and basin.The Shuitianba fault related with Zigui sycline thrusted to SEE.The major stress field was parallel bunchiness.And the deformation may be related with the Xuefengshan thrust belt whcih was barriered by Huangling anticline when thrusting to NW.D3 is that the nearly SN hinge of Zigui sycline bent to SW,and Badong synclinorium was arc been convex to NW,and the western segment of the Xianglongshan anticline was superposition by the structural features.The major stress field was generally divergent to NW.This deformation may be connected with that Xuefengshan thrusted to NW.Those sructural analysises show that Dabashan belt thrust
出处
《地质学报》
EI
CAS
CSCD
北大核心
2014年第8期1382-1400,共19页
Acta Geologica Sinica
基金
973计划课题(编号2014CB440903)
国家自然科学基金项目(编号41372212)
教育部博士点基金项目(编号20120022110013)的资助成果
关键词
秭归褶皱带
大巴山逆冲带
雪峰山逆冲带
复合过程
鄂西
Zigui fold belt
Dabashan thrust belt
Xuefengshan thrust belt
compounding process
western Hubei
