地学前缘 ›› 2010, Vol. 17 ›› Issue (3): 191-199.

• 论文 • 上一篇    下一篇

北大巴山逆冲推覆构造带前缘构造特征及变形年代学研究

李鹏远, 张进江, 郭磊, 杨雄英   

  1. 造山带与地壳演化教育部重点实验室; 北京大学 地球与空间科学学院, 北京 100871
  • 收稿日期:2010-03-18 修回日期:2010-05-08 出版日期:2010-05-15 发布日期:2010-06-18
  • 作者简介:李鹏远（1986—），男，硕士研究生，构造地质学专业。Email: lpy@pku.edu.cn
  • 基金资助:

    国家自然科学基金项目(40821002);中国石油化工集团公司项目“中国南方(中上扬子)大陆构造与海相油气前景”(YPH0800101)

Structural features and deformational ages in the front of the northern Dabashan thrust belt.

 LI  Feng-Yuan, ZHANG  Jin-Jiang, GUO  Lei, YANG  Xiong-Yang   

  1. The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education; School of Earth and Space Sciences, Peking University, Beijing 100871, China
  • Received:2010-03-18 Revised:2010-05-08 Online:2010-05-15 Published:2010-06-18

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摘要：

在北大巴山推覆构造带前缘，北—北东倾斜的城口断裂和南—南西倾斜的高桥断裂形成一背冲式逆冲推覆体系，以两断层为界，其间为一巨型冲起构造。该冲起构造因边界断裂的产状特征、活动强度沿走向的差异，而表现出明显的分段性：其北西段为双向逆冲的“正花状”结构；而南东段为反向逆冲为主的“半花状”结构。同构造低温变质绢云母40Ar39Ar年龄显示，城口断裂在燕山期（约1433 Ma）存在一次强烈的构造活动，导致北大巴构造带进一步逆冲扩展和强烈隆升。在逆冲推覆向前扩展过程中，受锋缘外侧阻抗的影响，沿前缘部位形成一系列反向逆冲断层，从而形成巨型冲起构造。

关键词: 北大巴山, 逆冲推覆构造带, 反向逆冲断裂, 冲起构造, 40Ar39Ar年龄

Abstract:

In the front of northern Dabashan thrust belt, there is a huge popup structure bounded by the NNEdipping Chengkou fault in the south, and the SSWdipping Gaoqiao fault in the north. The popup structure can be divided into several different segments along its strike, due to the variance of the occurrence characteristics and intensity of tectonic activity. To the northwest, it is a bidirectional thrusting structure and displays a positive flower structure; by contrast, the southeastern part is composed of a vertical Chengkou fault and a series of northdirected backthrusts, showing a semiflower structure. The 40Ar39Ar dating of syntectonic microthermal metamorphic sericite showed that Chengkou fault had an intense deformation during Yanshanian epoch (about 1433 Ma), causing rapid uplifting and thrusting of northern Dabashan thrust belt. During the propagation of this thrusting, a series of backthrusts formed because of the obstruction from the frontier of Dabashan thrust belt, and as a result, the popup structure was built up.

Key words: northern Dabashan, thrust belt: backthrust, popup structure, 40Ar39Ar age

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