地学前缘 ›› 2012, Vol. 19 ›› Issue (5): 27-40.

• 论文 • 上一篇    下一篇

燕山板内造山带中部“承德逆冲构造”的褶皱相关断裂构造模型

张长厚，邓洪菱，李程明，刘孜，邓洪旦,滕飞   

  1. 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
    3. 瑞典乌普萨拉大学 地球科学系 汉斯兰博格构造实验室, 瑞典 乌普萨拉 75236
  • 收稿日期:2012-07-02 修回日期:2012-08-13 出版日期:2012-09-10 发布日期:2012-09-10
  • 作者简介:张长厚（1964—），男，教授，构造地质学专业，主要从事构造地质学和区域大地构造学教学和科学研究工作。E-mail：changhou@cugb.edu.cn
  • 基金资助:

    国家自然科学基金项目（90814002, 40672150, 40739906）；中国地质调查局地质调查工作项目（121201112073）

An outofsyncline thrust model for the “Chengde Thrust Sheet” in central intraplate Yanshan Orogenic Belt, northern North China Craton.

  1. 1. School of Earth Sciences and Resources, China University of Geosciences(Beijing), Beijing 100083, China
    2. State Key Laboratory Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China
    3. Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden
  • Received:2012-07-02 Revised:2012-08-13 Online:2012-09-10 Published:2012-09-10

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摘要：

燕山板内造山带中部承德盆地复杂的中生代褶皱及逆冲断裂构造，曾被解释为土城子组沉积之后大型逆冲推覆构造（位移量大于40~45 km）又经褶皱变形的结果。近年来，土城子组沉积相和物源区分析、中新元古界沉积古地理研究以及相关构造变形研究结果等，对这一变形大型逆冲构造模型提出了多方位质疑。但已有研究并未提出新的构造模型来解释这一复杂构造区域中生代构造变形样式和形成机制。文中通过对承德盆地区域主体构造——承德向斜、向斜两翼逆冲构造变形几何学与运动学特征、向斜转折端附近构造变形与断裂发育状况进行详细野外调查及对关键地质体同位素地质年代进行测试，发现承德向斜两翼逆冲断层为分别向向斜核部以外区域逆冲的独立逆冲断层，逆冲断层活动与承德向斜变形是在统一的收缩变形体制下准同时形成的。它们形成于土城子组之后、张家口组火山活动之前，即距今约139~136 Ma。据此提出了“承德逆冲构造”的背离向斜逆冲构造模型。这一模型合理地解释了燕山中部承德盆地区域中生代构造变形和相应的盆地充填特征，同时表明，燕山板内造山带并不存在碰撞造山带前陆褶皱逆冲带中常见的大型薄皮逆冲构造样式。这一研究结果展示了褶皱相关断裂构造模型在研究和揭示收缩构造变形区域大尺度褶皱与断裂构造相互关系及准确重建区域构造演化过程方面的重要意义。

关键词: 逆冲构造；褶皱相关断裂；背离向斜逆冲构造, 承德；燕山

Abstract:

The complicated and enigmatic Jurassic folds and thrusts around Chengde Basin in central intraplate Yanshan Orogenic Belt were previously interpreted as a synclinal deformed thrust sheet with largedisplacement (~＞4045km) formed after Late Jurassic Tuchengzi Formation. This model has been challenged by many new findings in paleogeographic and provenance analysis of Tuchengzi Formation and Proterozoic Changcheng System, together with the research result in tectonic deformations. Meanwhile no new model has been proposed so far to account reasonably for the structural style and tectonic framework as well as the evolution process of this structurally complicated region. Detailed mapping have been conducted in last several years to reveal systematically the geometric and kinematic features of the Chengde syncline and thrust faults developed in its both limbs and around its exposed hinge zone to the east. UPb age dating with LAMCICPMS method on zircons from key terranes of Chengde Basin has been employed to constrain the timing of major deformations. We found that the thrust faults in northern and southern limbs of the Chengde syncline are independent thrust faults moving away from the core of the syncline. They died out around the hinge zone separately other than connected to each other to form a unified thrust fault as expected by synclinal deformed thrust sheet model. Age dating results suggested that both the Chengde syncline and the major thrust faults formed around 139136 Ma. Based on recent research results aforementioned，an outofsyncline thrust model has been proposed in this paper. The complicated geometric and kinematic features of folds and thrust faults in Chengde Basin as well as the provenance features of Tuchengzi Formation can be interpreted reasonably with this new model. This research implies that there is no largescale thinskinned thrust tectonics in intraplate Yanshan Orogenic Belt as those in foreland fold and thrust belt of collision orogenic belt. Foldaccommodation fault is supposed to be treated as an important alternative model in dealing with the relationship between largescale folds and thrust faults as well as tectonic framework and evolution in contraction regime.

Key words:  thrust tectonics, foldaccommodation fault, outofsyncline thrust, Chengde, Yanshan