珠江口盆地前新生代先存断裂特征及动力背景——以惠州凹陷和番禺4洼为例  

Characteristics and dynamic background of pre-existing fractures in pre-Cenozoic of Pearl River Mouth Basin:cases of Huizhou Sag and Panyu 4 Depression

作　　者：吴婷婷 张丽丽 吴哲 李洪博 雷胜兰 于飒 劳妙姬 WU Tingting;ZHANG Lili;WU Zhe;LI Hongbo;LEI Shenglan;YU Sa;LAO Miaoji(Shenzhen Branch of CNOOC(China)Ltd.,Shenzhen 518054,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,深圳518054

出　　处：《海洋地质前沿》2022年第6期54-62,共9页Marine Geology Frontiers

基　　金：中海石油(中国)有限公司重大生产科研项目“珠江口盆地(东部)浅水区古近系油气成藏条件及勘探突破方向”(SCKY-2020-SZ-21)。

摘　　要：前人针对珠江口盆地前新生代开展过大量研究,但对盆地的原始构造格局仍缺乏统一认识。在高精度三维地震资料的基础上,笔者采用“定性+定量”先存断裂综合识别技术,识别出珠江口盆地惠州凹陷和番禺4洼前新生代基底发育的先存断裂583条。按照断裂是否断穿Tg和断裂倾角大小,将先存断裂分为4类:高角度节理、低角度节理、高角度活化断层和低角度活化断层;按断裂走向划分,将先存断裂分为NW-NWW向和NE-NEE向2组。燕山期晚侏罗−早白垩世,古太平洋板块对华南板块沿NW向正向俯冲,形成NE-NEE向逆冲断裂;燕山期晚白垩世,古太平洋板块对华南板块斜向俯冲产生左旋挤压应力场导致NWNWW向逆冲断裂形成。这些先存断裂从源头上控制了珠江口盆地的构造格局,为研究盆地后续演化提供了重要支撑。Although previous many studies on the pre-Cenozoic stratigraphy of the Pearl River Mouth Basin have been done,there is still a lack of unified understanding of the original structural pattern of the basin.With available high-precision 3D seismic data,we implemented“qualitative+quantitative”comprehensive identification technology for the recognition of pre-existing fractures,by which 583 pre-existing fractures in the pre-Cenozoic basement of Huizhou Sag and Panyu 4 Depression in the Pearl River Mouth Basin were identified at the end.According to whether the fault runs through reflector Tg(the seismic horizon at the basement)and the fault dip angle,we divided the pre-existing fracture into four types:high-angle joint,low-angle joint,high-angle re-active fault,and low-angle re-active fault.In addition,according to the fractures’strike,we classified the pre-existing fractures into two groups:NW-NWW and NE-NEE.From the Late Jurassic to Early Cretaceous,the paleo-Pacific Plate subducted into the South China Plate perpendicularly in NW direction and formed NE-NEE thrust faults;in the Late Cretaceous,the paleo-Pacific Plate subducted into the South China Plate obliquely and produced a sinistral compressive stress field,resulting in the formation of NW-NWW thrust faults.These pre-existing fractures control the overall structural pattern of the Pearl River Mouth Basin,and provide an important support to the future study on the subsequent evolution of the basin.

关 键 词：珠江口盆地 前新生代基底 先存断裂 成因机制 

分 类 号：P736[天文地球—海洋地质] P542.3[天文地球—海洋科学]