生长地层分析法在研究反转构造形成时间中的应用——以南海北部湾盆地雷东凹陷为例

Application of Growth Stratum Analyzing Method in Study the Formation Time of Reverse Structure-an Example of Leidong Sag in Beibuwan Basin

刘志峰 梁建设 徐建永 印斌浩

LIU Zhifeng LIANG Jianshe XU Jianyong YIN Binhao

中海油研究总院, 北京 100027

CNOOC Research Institute, Beijing 100027, China

含油气区反转构造形成时间的推断,对于油气勘探具有十分重要的地质意义。雷东凹陷发育反转构造,其现今为背斜形态且与生长地层共生。生长地层即同构造沉积地层,常伴随着地层褶皱变形而同期发育。生长地层与褶皱变形的地层之间存在着必然联系。生长地层分析法认为,通过分析生长地层开始和结束"生长"的时间,就可以确定反转构造的形成时间。依据地层沉积角度和接触关系,可将雷东凹陷的生长地层划分为3个期次,其中第1期地层的底对应于上渐新统的底界面,第3期地层的顶对应于上渐新统的顶界面,据此推断出该区反转构造形成于晚渐新世期间,而又由于构造活动的间歇性,使其分为三个阶段逐期发育而成。

It is significant to infer the formation time of a reverse structure for oil and gas exploration in a hydrocarbon potential area. The reverse structures are well developed in Leidong Sag in Beibuwan Basin forms, being an anticline now, coexisting with growth strata. The growth strata, namely syn-tectonic sedimentary formation, deposited accompanying with the strata folding and deforma-tion. The growth stratum has a causal relationship with the formation of reverse structure and strata folding. Through analyzing the beginning time and the end time of the growth stratum, the formation time of reverse structure can be determinated. On the basis of the depositional angle and contact relationship, the development of growth strata in Leidong Sag can be divided into in three stages, of which the bottom of the Phase-1 growth strata corresponds to the bottom boundary of the Upper Oligocene, and the top of the Phase-3 growth strata corresponds to the top boundary of the Upper Oligocene. Therefore, it can be concluded that the reverse struc-ture formed in Late Oligocene, and developed during three stages due to the intermittence of tectonic activity.

国家科技重大专项课题"近海富烃凹陷资源潜力再评价和新区、新领域勘方向"(编号:2011ZX05023-001)部分研究成果。

https://doi.org/10.3969/j.issn.1008-2336.2013.01.023