南海南沙地块新生代层序地层格架及构造演化模式  

Cenozoic sequence stratigraphic framework and tectonic evolution model of Nansha block in South China Sea

作　　者：唐武 赵志刚 谢晓军 宋双 王一博 刘世翔 TANG Wu;ZHAO Zhigang;XIE Xiaojun;SONG Shuang;WANG Yibo;LIU Shixiang(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《中国海上油气》2021年第2期67-77,共11页China Offshore Oil and Gas

基　　金：“十三五”国家科技重大专项“曾母-北康盆地群油气地质条件研究与勘探方向选择(编号:2016ZX05026-004)”;国家自然科学基金重大研究计划“南海深海地质演变对油气资源的控制作用(编号:91528303)”部分研究成果。

摘　　要：以北康盆地为例,运用层序地层学和沉积学的原理和方法,通过地震、钻井、测井等资料的综合分析,建立了区域性新生代层序地层格架;在厘清区域构造事件的基础上,结合地层发育特征,提出了南沙地块构造层序演化模式。研究表明,北康盆地新生代地层可划分为3个构造层序和8个三级层序,各层序界面在地震上可见明显的削截或上超反射特征,钻测井上表现为测井曲线形态或岩相组合的突变。新生代以来南海周缘不同构造事件及其响应对南沙地块构造层序演化阶段的准确划分具有非常重要的指导作用,北康盆地新生代经历了断拗期(I幕和II幕)、转换期、拗陷期等3个构造演化阶段:断拗期,断裂体系发育,以浅水沉积为主;转换期,盆地隆升,以内部短距离搬运物源为主;拗陷期,断裂体系活动微弱,发育深水沉积体系。相应地,南沙地块新生代发育漂移前、漂移期、碰撞期、漂移后等4期构造层序:漂移前期,发育一系列地堑或半地堑结构;漂移期,随着南海扩张作用,逐渐与北部陆缘分离,远离大陆物源,向南漂移,发育碳酸盐岩;碰撞期,与婆罗洲地块发生碰撞,南海扩张作用终止;漂移后期,发生快速沉降,进入深水沉积环境。本文研究可为北康盆地下一步勘探工作部署提供参考依据,对整个南沙地块构造层序演化和沉积充填的深入研究具有一定的借鉴作用。By taking Beikang basin as an example,with the principles and methods of sequence stratigraphy and sedimentology,through comprehensive analyses of seismic,drilling and logging data,the Cenozoic sequence stratigraphic framework of Beikang basin was established.Besides,based on the analysis of the regional tectonic events and stratigraphic characteristics,the tectonic sequence evolution model of Nansha block was proposed.The results show that Cenozoic strata of Beikang basin can be divided into three tectonic sequences and eight three-order sequences,with obvious truncation or over reflection characteristics observed on seismic profiles of each sequence boundary and abrupt change of logging curve shape or lithofacies combination.Different tectonic events and their responses around the South China Sea since Cenozoic have played a very important guiding role in the accurate division of tectonic sequence evolution stages of the Nansha block.The Beikang basin experienced three tectonic evolution stages throughout Cenozoic:fault-depression stage(episode I and episode II),transition stage and depression stage.Fracture systems were developed in the fault-depression stage,with shallow water deposite developed.Within the transition stage,the basin was uplifted and dominated by internal short-distance transportation of material sources.During the depression stage,the fracture activities were weak,with deepwater depositional system developed.Correspondingly,four tectonic sequences were developed in the Nansha block,namely pre-drifting period,drifting period,collision period and post-drifting period.During the pre-drifting period,a series of graben or semi-graben structures were developed in the Nansha block.During the drifting period,with the spreading of the South China Sea,it gradually separated from the northern continental margin,drifted southward,with carbonate developed.During the collision period,the basin collided with the Borneo block,resulting in the termination of the spreading of the South China Sea.In the post-dr

关 键 词：南沙地块 北康盆地 新生代 层序地层格架 构造演化模式 

分 类 号：TE121.3[石油与天然气工程—油气勘探]