南海西北部莺琼陆坡重力流和等深流的时空关联  

Spatio-temporal relationship between two kinds of deep-water sedimentation on the Ying-Qiong slope,South China Sea

作　　者：王海荣[1,2] 余承谦 樊太亮[1,2] 柴京超 王宏语[1,2] 高红芳[4] WANG Hairong;YU Chengqian;FAN Tailiang;CHAI Jingchao;WANG Hongyu;GAO Hongfang(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Key Laboratory of Strategy Evaluation for Shale Gas of Ministry of Land and Resources,China University of Geosciences(Beijing),Beijing 100083,China;The Exploration Enterprise Department of Qinghai Oilfield Company,Dunhuang 736202,China;Guangzhou Marine Geological Survey,Guangzhou 510098,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]中国地质大学(北京)页岩气勘查与评价国土资源部重点实验室,北京100083 [3]青海油田勘探事业部,甘肃敦煌736202 [4]广州海洋地质调查局,广东广州510760

出　　处：《地学前缘》2023年第4期196-208,共13页Earth Science Frontiers

摘　　要：南海西北部的莺琼陆坡深水区近些年获取了大量油气发现,展示了广阔的勘探前景。深水沉积往往受控于重力流、等深流等多种机制,它们在时空中如何分布、如何相互作用,又在多大程度上影响或控制着沉积格局,对水动力方面的认识的差异会导致沉积相展布方面的不同认识,进而影响对砂体类型和展布的分析,制约了石油勘探开发。论文基于地震数据所呈现的地震相和地层叠置样式,确认莺琼陆坡在中新世以来发育两类沉积体系:重力(流)和等深流沉积体系。二者在时空上存在毗邻而居、有序进退的关系,重力流沉积呈“台阶状”逐层上超于等深流沉积之上,呈进积形态,而等深流沉积体系则呈退积样式;二者之间构成了特殊成因的、跨时的“相变”面;进而相应恢复了两种不同方向的沉积作用(重力流和等深流)的时空关联。它们这种“台阶状”进退关系根源于中中新世以来莺琼陆坡所经历的多方向物源体系充沛的碎屑供应和由此导致的活跃的重力流活动;南海深水循环导致的等深流机制作用的强度也有相当的作用;总体上,等深流沉积体系的分布范围受重力流作用强弱的控制,形成了二者彼进此退的时空关系。Large amounts of oil and gas are discovered in recent years in the Yingqiong slope deep-water area,northwestern South China Sea,demonstrating the region’s high potential for oil and gas exploration and production.Deep-water sedimentation is often controlled by various mechanisms including gravity flow and contour current.Where and when these mechanisms operate and interact,and to what extent they affect or control sedimentary patterns,can result in different understandings of the regional sedimentary facies distribution due to spatio-temporal variability of hydrodynamic properties.This in turn can complicate the determination of sand body type and distribution and thus hinder gas and oil exploration and development in the region.Based on the seismic facies and stratigraphic superimposed pattern presented by the seismic data,this paper confirms the existence of two types of Miocene sedimentary systems on the Yingqiong slope:gravity(flow)and contour current sedimentary systems.These two systems are adjacent to each other sequentially in time and space,with the former superimposing over the latter in a stepwise pattern prograding towards the slope while the latter exhibiting a retrograde pattern.The boundary between the two systems indicates a special,diachronic“facies transition”interface,and,accordingly,the spatio-temporal relationship between the two distinct sedimentary processes(gravity flow and contour current)is restored.The stepwise progradation-retrogradation relationship between the two sedimentary systems can be attributed to three factors:the abundant supply of clastic materials from a multi-directional Middle-Miocene source system;the resulting strong gravity flow activity;and contour currents induced by deep-water circulation in the South China Sea.The magnitude of gravity flow largely controls the distribution range of the contour current sedimentary system,leading to a spatio-temporal stepwise progradation-retrogradational pattern.

关 键 词：南海 莺琼陆坡 深水 重力流作用 等深流作用 

分 类 号：P736.21[天文地球—海洋地质]