沉积学报2025，Vol.43Issue(6)：2187-2201,15.DOI:10.14027/j.issn.1000-0550.2024.121
琼东南盆地松南低凸起YA区渐新统沉积体系
The Oligocene Sedimentary System in the YA Area of the Songnan Uplift,Qiongdongnan Basin
摘要
Abstract
[Objective]Systematic study of sedimentary systems and models is the foundation for clarifying the develop-ment mechanism of high-quality reservoirs in clastic rocks.[Methods]A systematic study was conducted using drill cores,thin section and paleontological fossil identification,grain size analysis,well-logging and seismic interpreta-tion of the sedimentary system and evolution of the Oligocene in the study area to restore the sedimentary environment of the Paleogene.[Results]The lithology of the lower part of the Oligocene(Yacheng Formation)is mainly composed of medium coarse sandstone and conglomerate sandstone.The sandstone is poorly sorted,with mineral composition gradually stabilizing and maturity gradually increasing upwards from bottom to top.The cumulative curve of particle size probability shows suspended and jumping characteristics,with extremely low fossil abundance.The sedimentary facies types are mainly fan delta,shore shallow lake and lakeshore plain.The lithology of the upper part of the Oligocene(Lingshui Formation)is mainly composed of fine sandstone and mudstone,with a significant increase in fossil abundance.The sedimentary facies are mainly coastal shallow marine,shallow-water continental shelves and deep-water continental shelves.The study area underwent a transition from marine terrestrial transitional sedi-mentation to shallow marine sedimentation during the Oligocene.During the depositional period of the Yacheng For-mation,the basin was experiencing strong faulting and rapid compensation.The main features of the seismic phases are accumulative and chaotic reflection structures.Fault activity in the area led to the formation of a structural pattern with alternating concave and convex features,resulting in shallow water bodies.Shallow lake facies were developed at the center of the depression and fan delta facies are developed on steep slopes and deeper water bodies.Braided river delta facies are present on gentle slopes and shallower water bodies.During the sedimentation period of the Lingshui Formation,the basin was undergoing rapid faulting and under-compensation.The seismic phase is mainly characterized by parallel sub-parallel reflection structures.Fracture activity caused the deepening of sedimentary water bodies.The overall development resulted in both shallow-and deep-water shelf facies in the center of the depression,with sporadic fan delta facies around the periphery.[Conclusions]The Oligocene in the YA area is a strongly faulted sedimentary system in which the sedimentary facies types and distribution were significantly influenced by tectonic movement.The filling style and sedimentary evolution of the basin reflect its sedimentary pattern during that period of time.关键词
琼东南盆地/松南低凸起/渐新统/沉积体系/沉积模式Key words
Qiongdongnan Basin/Songnan low uplift/Oligocene/sedimentary system/sedimentary pattern分类
天文与地球科学引用本文复制引用
GUO YuanCao,GUO JianHua,YU Ye,CHEN Guang,LI ZhiYu,LIU ChenSheng,WU ShiQing..琼东南盆地松南低凸起YA区渐新统沉积体系[J].沉积学报,2025,43(6):2187-2201,15.基金项目
国家科技重大专项(2016ZX05026-002)[National Science and Technology Major Project,No.2016ZX05026-002] （2016ZX05026-002）
