地学前缘 ›› 2009, Vol. 16 ›› Issue (3): 49-68.

• 论文 • 上一篇    下一篇

秦岭造山带大巴山弧形构造带中生代构造变形

胡健民 施炜 渠洪杰 陈虹 武国利 田蜜   

  1. 1中国地质科学院 地质力学研究所, 北京 100081
    2中国科学院 地质与地球物理研究所, 北京 100029
  • 出版日期:2009-05-01 发布日期:2009-05-01
  • 作者简介:胡健民(1959—),男,研究员,从事构造地质学、造山带与盆地构造、南极地质研究。Email: jianminhu@vip.sina.com
  • 基金资助:

    国家自然科学基金项目(40830314,40272097)

Mesozoic deformation of Dabashan curvilinear structural belt of Qinling orogen

HU Jian-Min SHI Wei JU Hong-Jie CHEN Gong WU Guo-Li TIAN Mi   

  1. 1Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
    2Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
  • Online:2009-05-01 Published:2009-05-01

摘要：

大巴山构造带位于秦岭造山带南部,一直被认为是华北、扬子板块碰撞带前陆逆冲推覆构造带。研究表明,位于城口—房县断裂之南的大巴山弧形构造带,经历了两次明显的叠加变形过程。大巴山弧形构造带由轴向弧形延伸的线状褶皱与弧形弯曲的逆冲断层组成(D2),是南大巴山主期变形产物。弧形构造带西段褶皱轴向为北北西—近南北向,叠加在先前轴向近东西向的开阔宽缓的褶皱(D1)之上,形成典型横跨叠加构造。弧形构造带中段和东段,褶皱轴向逐渐转变为近东西向。构造填图显示,在弧形带形成之前,发生过一期轴向北东到北北东向褶皱为主的变形(D1)。据变形序列、卷入的地层以及区域构造关系判断,西段与中、东段D1变形时代均为晚三叠世—早侏罗世,很可能与华北、扬子的碰撞相关。而相关的地质、同位素年代学及磷灰石裂变径迹资料显示,大巴山弧形构造带主期变形(D2)的变形时代为晚侏罗世—早白垩世(160~110 Ma)，所以大巴山弧形构造带记录了两期不同系统构造变形的叠加,这对研究秦岭造山带的演化,具有重要意义。

关键词: 秦岭造山带;大巴山弧形构造带;中生代变形;滑脱拆离构造

Abstract:

 

Abstract:  The Dabashan structural belt is a part of south Qinling Mountains, which has been regarded as a foreland thrusting belt of the collisional belt of the north and south China plates. The results of the researches show that the curvilinear structural belt, to the south of ChengkouFangxian thrust fault in the Dabashan mountains, has undergone strong superimposed deformation during the Mesozoic. The Dabashan curvilinear structural belt is composed of linear folds with curvilinear fold hinges and some curvilinear thrust faults (D2), which was formed during the major phase of deformation of south Dabashan. In the western curvilinear structural belt, the folds of D2 with fold axes of nearly south to north trending superimposed on the early wide folds with axis of nearly west to east (D1), and formed a typical cross superimposed structure. In the central and eastern parts, fold axes of D2 were gradually turned to nearly eastwest. The geological mapping shows that there existed a phase of deformation that the fold axes were of north to nearly south to north direction before the formation of the curvilinear structural belt. Based on the deformational sequence, deformed strata, and regional geology, the authors believe that the time of D1, both in western and in central and eastern Dabashan curvilinear structural belt, is the late Triassic to the early Jurassic. It is possible that the deformation D1 was related to the collision between north China block and Yangtze block. On the other hand, the geological relationship, geochronology and AFT data show that the main deformation time of D2, is about the late Jurassic to the early Cretaceous(160110 Ma). So the Dabashan curvilinear structural belt recorded two phases of deformation which were formed during different tectonic settings. It is of great significance for the understanding of the evolution of Qinling orogen.

Key words: Key words: Qinling orogen; Dabashan curvilinear structural belt; Mesozoic deformation; detachment deformation

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