大巴山晚中生代陆内造山构造应力场  

The Tectonic Stress Field in the Dabashan Orogen Resulting from Late Mesozoic Intra-Continental Orogeny

作　　者：董树文[1] 施炜[2] 张岳桥[2] 胡健民[2] 张忠义[3] 李建华[2] 武红岭[2] 田蜜[2] 陈虹[2] 武国利[2] 李海龙[2] 

机构地区：[1]中国地质科学院,北京100037 [2]中国地质科学院地质力学研究所,北京100081 [3]北京矿产地质研究院,北京100012

出　　处：《地球学报》2010年第6期769-780,共12页Acta Geoscientica Sinica

基　　金：中石化海相前瞻性研究专项"大巴山前陆构造演化与油气远景研究"(编号:YPH08023);深部探测与实验研究专项(编号:SINOPROBE-08-01);中国地质科学院地质力学研究所基本科研项目"川东北构造体系联合复合及其对区域油气控制的研究"(编号:DZLXJK200715)联合资助

摘　　要：位于中上扬子板块北缘的大巴山造山带,平面上表现为一大尺度向南西显著突出的弧形带,无论在变形样式和形成时间上都明显与秦岭造山带不同。在大巴山构造格架划分和野外构造变形观测的基础上,通过构造解析,结合年代学研究成果,重建了大巴山晚中生代独特的构造应力场,指出大巴山属陆内造山,形成于J2末,并持续到K1末期。其构造应力场特征,以城口-房县断裂为界,大巴山逆冲推覆带与其前陆冲断褶皱带的特征显著不同。大巴山逆冲推覆带主要表现为NE-SW向构造挤压,而在大巴山弧形前陆带从西向东,由近E-W向挤压,转变为NE-SW向挤压,最后转变为近S-N向挤压,构成一向其外缘扩散的放射状构造应力场。总体上,大巴山造山带由推覆体向前陆,构造挤压作用由北东向南西方向扩散。这期构造挤压作用控制了大巴山造山带陆内变形,导致大巴山由北东向南西的显著缩短,同时受到其东西两侧基底隆起——神农架-黄陵地块与汉南地块的强烈阻挡,造就了现今的大巴山前陆弧型构造。其动力学背景可归因于晚中生代东亚板块多向汇聚。大巴山晚中生代陆内造山构造应力场的研究,对探讨秦岭造山带动力学特征具有科学意义,为研究川东北油气运聚规律提供了构造地质学依据。The Dabashan orogen, situated in the northern margin of the middle-upper Yangtze block, is marked by a large-scale oroclinal structure belt evidently extruding southwestwards. By dividing its framework and observing defor- mation in the field work, and combining with geochronologic data obtained in recent years, the authors rebuilt a stage of special stress field in the Dabashan orogen, which occurred during Late Mesozoic （late Middle Jurassic-early late of Early Cretaceous） and caused by intense intra-continental orogeny. The episode of the stress field, bounded by the Chengkou-Fangxian fault, is characterized by NE-SW trending tectonic compression in the Dabashan thrust belt, and outward emanational compression in the Dabashan foreland belt which is featured by E-W trending compression in the west segment, NE-SW striking compression in the middle, and S-N trending compression in the east, respectively, that is, it is approximately perpendicular to the oroclinal belt. Thus, controlled by the stage of stress field, and blocked from the two blocks of its west and east sides, the arc-shaped Dabashan foreland finally formed, which resulted from multidirec- tional convergence occurring in eastern Asia in late Mesozoic.

关 键 词：大巴山造山带 晚中生代 构造应力场 弧形构造 陆内造山 多向汇聚 

分 类 号：P548[天文地球—构造地质学] P553[天文地球—地质学]