石油学报 ›› 2012, Vol. 33 ›› Issue (5): 798-806.DOI: 10.7623/syxb201205008

• 地质勘探 • 上一篇    下一篇

南海北部白云凹陷21Ma深水重力流沉积体系

李 磊 1 王英民 2 徐 强 3 李 冬 3   

  1. 1 西安石油大学地球科学与工程学院 陕西西安 710065;2 中国石油大学地球科学学院 北京 102249;3 中海油研究总院 北京 100027
  • 收稿日期:2011-12-17 修回日期:2012-05-30 出版日期:2012-09-25 发布日期:2012-11-27
  • 通讯作者: 李 磊
  • 作者简介:李 磊,男,1979年3月生, 2001年毕业于西南石油大学,2010年获中国石油大学(北京)博士学位,现为西安石油大学讲师,主要从事深水沉积及储层预测研究。
  • 基金资助:

    国家重点基础研究发展计划(973)项目(2009CB219407)和国家自然科学基金项目(No.40572067)资助。

21 Ma deepwater gravity flow depositional system in Baiyun sag, northern South China Sea

LI Lei 1 WANG Yingmin 2 XU Qiang 3 LI Dong 3   

  • Received:2011-12-17 Revised:2012-05-30 Online:2012-09-25 Published:2012-11-27

摘要:

深水重力流沉积是南海北部陆坡主要的沉积类型,以高分辨率三维地震、钻测井等资料为基础,通过地震资料解释和地质分析,对南海北部白云凹陷21 Ma所发育的深水沉积体系进行识别、解释和预测。识别出块体搬运沉积体系、水道堤岸复合体以及朵体3类深水重力流沉积单元。块体搬运沉积体系呈杂乱反射特征,底部发育侵蚀擦痕;水道作为重力流的搬运通道,呈弱振幅U或V形特征;重力流溢流形成的堤岸呈强振幅楔形特征;水道与堤岸构成水道堤岸复合体具有典型的海鸥翼状特征;位于水道前端的朵体表现为强振幅平行—亚平行反射,在平面上具有朵状特征。块体搬运沉积体系逐渐向水道、水道堤岸复合体以及朵体演化的过程中伴随着不同流态的深水重力流之间的相互转化。综合地球物理学、沉积学以及海洋地质学等方法,对南海北部陆坡21 Ma开展重力流沉积体系研究,建立深水沉积模式,对研究深水重力流沉积过程具有重要的理论意义。

关键词: 白云凹陷, 深水, 重力流, 沉积体系, 南海

Abstract:

Deepwater gravity flow deposits are one of the main depositional types on the slope of the northern South China Sea. Based on high-resolution 3D seismic data, drilling data and logging data, and integrated with geophysical date interpretation and geological analysis, we identified, interpreted and forecasted a 21 Ma deepwater depositional system developed in Baiyun sag, northern South China Sea. The results showed that three types of deepwater gravity-flow deposits were identified, i.e. mass-transport, channel-levee complex and lobate deposits. The mass-transport deposit (MTD) has a chaotic seismic reflection with basal erosion scratches. The channel-levee complex deposit is characteristic of a “gull-wing” seismic reflection, of which the former (channel) shows a low-amplitude U- or V-shaped seismic reflection and acts as a main pathway for deepwater gravity-flow deposits, while the latter (levee) formed by the overflow of gravity flow is of a high-amplitude wedge-shaped reflection. A high-amplitude parallel to sub-parallel seismic reflection is interpreted to represent the lobate deposit, which is located in front of the channel and comes in a lobe-like shape on plane. Gradual evolution from the mass-transport deposit to the channel, channel-levee complex or labate deposit is often accompanied with a reciprocal transformation of various flow patterns of deepwater gravity flow. The research integrated geophysics, sedimentology and marine geology with the observation of the 21 Ma deepwater gravity-flow depositional system in Baiyun sag, northern South China Sea to establish a deepwater sedimentary model, which is of the theoretic significance in studying various depositional processes of deepwater gravity flow.

Key words: Baiyun sag, deepwater, gravity flow, depositional system, South China Sea