石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (3): 720-734.doi: 10.11743/ogg20230315

• 油气地质 • 上一篇    下一篇

渤海海域印支期逆冲推覆体系的分带性及其动力学成因机制

吕丁友(), 杨海风, 于海波, 刘朋波, 邓辉, 张参   

  1. 中海石油(中国)有限公司 天津分公司,天津 300452
  • 收稿日期:2023-01-22 修回日期:2023-04-06 出版日期:2023-06-01 发布日期:2023-06-05
  • 第一作者简介:吕丁友(1974—),男,博士、高级工程师,海上油气勘探与科研管理。E-mail:lvdy@cnooc.com.cn
  • 基金项目:
    中海石油(中国)有限公司“七年行动计划”重大科技专项(CNOOC-KJ 135 ZDXM 36 TJ 08 TJ)

Zonation and dynamic genetic mechanism of the Indosinian thrust nappe system in Bohai Sea

Dingyou LYU(), Haifeng YANG, Haibo YU, Pengbo LIU, Hui DENG, Shen ZHANG   

  1. Tianjing Branch,CNOOC,Tianjin 300452,China
  • Received:2023-01-22 Revised:2023-04-06 Online:2023-06-01 Published:2023-06-05

摘要:

印支期是改变整个中国东部陆内构造变形样式的一次极为重要的构造活动期,但目前对其认识主要基于对华北克拉通周缘造山带及渤海湾盆地陆域的研究,而对渤海海域中生代构造演化的研究相对薄弱。基于最新的三维大连片地震数据,对渤海海域印支期变形开展了详细的构造解析工作,并提出印支期逆冲推覆系统可划为以下3个逆冲带:①第一逆冲带位于沙垒田凸起、渤中19-6构造区和渤南低凸起一线,为高角度冲出带,表现为太古宇基底在印支期沿逆断层高角度逆冲,部分出露地表并长期遭受风化剥蚀,导致该区域缺失古生界,高角度逆冲断层随后在燕山期和喜马拉雅期转换为走滑断层,对应于现今张家口-蓬莱断裂带的渤海湾段;②第二逆冲带为位于渤中凹陷和渤东凹陷的逆冲-褶皱中部带,其古生界主要表现为断层相关褶皱式的变形特征,特别是在渤东凹陷可识别出典型的叠瓦式构造和双重构造;③第三逆冲带为位于辽东湾坳陷的逆冲推覆前锋带,其古生界变形主要表现为宽缓的背斜、向斜构造,这一系列背斜和向斜与盆地基底内隐伏的印支期坡坪式逆冲推覆断层有关,为典型的断展或断滑褶皱。基于横切整个渤海海域的地震剖面及前人的研究资料,认为3个逆冲推覆带的空间组合受控于三级台阶式的印支期基底滑脱层。渤海海域这种印支期逆冲推覆体系分带性可能与华北克拉通不同区域的基底性质差异有关,即鲁西基底在印支期沿滑脱层逆冲至燕辽基底之上,并导致上覆古生界沉积盖层具有分带性的褶皱变形特征。

关键词: 成因机制, 滑脱层, 构造分带性, 逆冲推覆系统, 印支期, 渤海海域

Abstract:

The Indosinian orogeny is a key period shaping the intracontinental deformation pattern in eastern China. Current understanding of the Indosinian tectonism period is mainly based on the study of the orogenic belt around the North China Craton and the continental area of the Bohai Bay Basin. However, little research attention has been paid to the Mesozoic tectonic evolution in the Bohai Sea. Based on the latest three-dimensional seismic reflection data, we present a detailed structural analysis of the Indosinian deformation in the Bohai Sea and propose that the Indosinian thrust nappe system can be divided into the three thrust zones as follows. The first thrust zone along Shaleitian salient, Bozhong 19-6 structural zone and the Bonan sub-salient, is a high-angle trust structure as shown by the Archaean basement thrust at high angle along reverse fault with part outcropped and subject to long-term weathering and denudation during the Indosinian period, resulting in the absence of the Paleozoic. The high-angle thrust faults turned into strike-slip faults as shown by the present-day Bohai Bay section along the Zhangjiakou-Penglai fault zone. The second one, the central thrust-fold zone located in the Bozhong and Bodong sags, is mainly characterized by fault-related fold deformation in the Paleozoic strata, especially in the Bodong Sag, where typical imbricates and duplex structures can be identified. The third thrust zone, the front belt of the thrust nappe located in the Liaodong Bay Depression, is mainly characterized by extensive and gentle anticlines and synclines under the Paleozoic deformation, typical fault-propagation or fault-detaching folds, which are associated with the hidden thrust nappe faults of slope-plateau type in the basin basement during the Indosinian. We may conclude through the seismic section across the entire Bohai Sea and previous research data, that the spatial association of three thrust nappe zones is controlled by the three-step basement detachment layers during the Indosinian period. The dynamic genetic mechanism of the Indosinian thrust nappe system in the Bohai Sea may be related to the differential basement features in the North China Craton, that is, the thrusting of Luxi basement against Yanliao basement along the decollement layer during the Indosinian, leading to the overlying Paleozoic caprock characterized by fold deformation in zonation.

Key words: genetic mechanism, detachment layer, tectonic zonation, thrust nappe system, Indosinian, Bohai Sea

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