南海北部双峰南陆坡深水区早-中中新世沉积充填特征及其影响因素

Sedimentary filling characteristics and the main controlling factors during the Early-Middle Miocene in the deep-water area of Shuangfengnan Slope in the northern South China Sea

钱星 张莉 易海 韦振权 帅庆伟

Qian Xing Zhang Li Yi Hai Wei Zhenquan Shuai Qingwei

国土资源部海底矿产资源重点实验室广州海洋地质调查局, 广州 510075

MLR Key Laboratory of Marine Mineral Resources, Guangzhou Marine Geological Survey, Guangzhou, Guangdong 510075, China

深水陆坡沉积是近年来我国海域油气勘探关注的重点。利用二维多道地震剖面及周边钻井资料,以外部形态和内部结构相结合的方式对南海北部双峰南陆坡区早-中中新世地层进行地震相分析,识别出斜交型前积、丘状前积、席状杂乱、席状平行4种地震相类型。结合研究区古地理及其邻区同时期的构造-沉积演化分析,认为其主要发育了陆架边缘三角洲、斜坡扇及滑塌体3种典型的沉积体,它们的发育与演化是构造运动、相对海平面变化及物源三方因素相互作用的结果。以华南及古珠江供源的三角洲体系是影响陆坡区沉积体系发育的最重要因素,是沉积体系发育的物质基础,构造运动和相对海平面变化为陆坡区沉积体系的发育提供了可容纳空间。

Deep-water deposition on the slope has become one of the major issues in China's offshore oil and gas exploration in recent years.We studied the seismic facies of the Shuangfengnan Slope in the northern South China Sea during the Early-Middle Miocene by combining external form and inner structure based on 2D multi-channel seismic and drilling data.Four typical seismic facies were recognized, including "S" type progradational seismic facies, mound type progradational seismic facies, parallel chaotic seismic facies, and parallel seismic facies. The paleogeographic evolution of the study area and the tectonic-sedimentary evolution of its adjacent area during the same period showed that three typical sedimentary systems (shelf-margin delta, slope fans, and slump deposits) were developed under the control of relative sea level change, provenance and the tectonic movement. The delta system with sources from South China and the Pearl River is the most important factor affecting the development of slope depositional system, and is the material basis of the depositional system. Tectonic movement and relative sea level change provided accommodation for the slope sedimentary system development.

国土资源部海底矿产资源重点实验室开放基金项目(KLMMR-2013-A-11)及"南海北部陆坡及台湾海峡盆地西部油气地质特征及赋存规律研究"项目([2013]GZH002-31)资助。

https://doi.org/10.11781/sysydz201506751