热带海洋学报 ›› 2017, Vol. 36 ›› Issue (5): 59-71.doi: 10.11978/2017007

所属专题: 南海专题

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南海北缘白云凹陷北坡裂后断裂活动特征及构造沉积响应*

谢志远1,4(), 杨建民2, 孙龙涛1(), 郑金云3, 孙珍1, 邱宁1   

  1. 1. 中国科学院边缘海与大洋地质重点实验室(南海海洋研究所), 广东 广州 510301
    2. 中海石油(中国)有限公司天津分公司, 天津 300452
    3. 中海石油(中国)有限公司深圳分公司, 广东 深圳 518067
    4. 中国科学院大学, 北京 100049
  • 收稿日期:2017-01-09 修回日期:2017-05-03 出版日期:2017-09-20 发布日期:2017-09-22
  • 作者简介:

    作者简介:谢志远(1990—), 男, 博士研究生, 主要从事海洋地质和构造地质研究。E-mail: xiezhiyuan1990@hotmail.com

  • 基金资助:
    “十二五”油气重大专项课题(2011ZX05025-003-005);NSFC-广东联合基金项目(U1301233);国家自然科学基金项目(41576070、41576068);广东省自然科学基金项目(2014A030313741)

The characteristics of post-rift fault activities and sedimentary response on the northern slope of the Baiyun Sag in the northern margin of the South China Sea

Zhiyuan XIE1,4(), Jianmin YANG2, Longtao SUN1(), Jinyun ZHENG3, Zhen SUN1, Ning QIU1   

  1. 1. CAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Guangzhou 510301, China
    2. China National Offshore Oil Corporation, Tianjin Branch, Tianjin 300452, China
    3. China National Offshore Oil Corporation, Shenzhen Branch, Shenzhen 518067, China
    4. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-01-09 Revised:2017-05-03 Online:2017-09-20 Published:2017-09-22
  • About author:

    Author:QIU Chunhua.E-mail: qiuchh3@mail. sysu.edu.cn

  • Supported by:
    National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period (2011ZX05025-003-005);Joint Program of National Natural Science Foundation of China and Guangdong Province (U1301233);National Natural Science Foundation of China (41576070, 41576068);Science Foundation of Guangdong Province (2014A030313741)

摘要:

为深入理解被动大陆边缘凹陷斜坡断裂的构造特征和演化机制, 利用最新的三维地震资料分析珠江口盆地白云凹陷北坡带的断裂发育特征, 应用断层生长指数研究断裂的活动期次, 结合断裂活动期间的沉积响应特点, 分析断层发育演化机制。结果显示, 白云凹陷北坡断裂走向以NWW向为主, 发育部分NEE至近E—W向小断裂; 断层倾角较陡, 单条断层剖面形态主要为板式断层, 组合构造样式主要呈阶梯状和“X”形断裂组合样式; 裂后阶段主要有23.03~21Ma和19.1~15.97Ma和10~2.59Ma三期活动, 其中10Ma后断层活动强度显著增大。断裂走向研究表明新生代区域伸展应力场由近N—S向向NNE向顺时针偏转, 偏转角度约为8°。相对于陆架凹陷发育的断裂, 位于陆坡深水区白云凹陷断裂体系特点主要是断裂活动时间较长且活动强度多变。研究表明, 白云凹陷北坡裂后断裂的发育演化主控因素是主凹持续强烈的热沉降, 南海扩张对北缘的弱挤压作用也是重要的影响因素, 南海块体和西菲律宾海板块的汇聚活动则对断裂构造活化有重要影响。白云北坡的沉积发育对构造活动具有较为明显的响应, 尤其是裂后第三期的构造活化期, 受东沙运动影响, 表现为一系列水道下切、深水沉积滑塌和削截抬升, 根据其变形特点, 推测东沙运动的构造应力主要来自东侧。

关键词: 白云凹陷, 裂后期断裂活动, 构造活化, 沉积响应

Abstract:

For deep understanding of the evolution of a fault in the passive continental margin slope, we analyzed the characteristics of fault activities and sedimentary response on the northern slope of the Baiyun Sag in this paper. Based on geological structural interpretation of 3D seismic profiles, fault activities were studied by using growth index. The results showed that the fault strike mainly is NWW-trending, while the rest are NEE- to EW-trending of small faults in the eastern and northern slope zones of the Baiyun Sag. In the vertical sections, these faults exhibited ladder and conjugated shaped combinations, while a single fault may be of planar shape. There were three episodes of post-rift fault activities, namely, 23.03-21 Ma, 19.1-15.97 Ma and 10-2.59 Ma. There has been a significant increasing activity since 10 Ma. The study of faults’ orientation indicates that Cenozoic stress field rotated clockwise from NS to NNE and the deflection angle is about 8 degrees. The main controlling factor of fault activities on the northern slope zone of the Baiyun Sag was the continuing strong abnormal subsidence and rapid sedimentation, while the rifting of the South China Sea was also an important factor that formed weak compressive stress on the northern margin; and the convergence between South China Sea plate and Philippine Sea plate played a key role in faults’ reactivation. Sedimentary units responded to tectonic movements directly in a series of deformation. The Dongsha Event was most obvious by canyon incisions, strata truncation and fault reactivation. We suggest the driving force came from the east.

Key words: Baiyun Sag, post-rift fault activities, tectonic reactivation, sedimentary response