滦平盆地陡坡带下白垩统西瓜园组水下粗碎屑岩沉积特征及搬运机制  

Sedimentary Characteristics and Transport Mechanism of Subaqueous Coarse Clastic Rocks in the Lower Cretaceous Xiguayuan Formation in the Steep Slope Zone of Luanping Basin

作　　者：杨保良 邱隆伟 杨勇强 董道涛 周士博 刘兆雯 白立科 Yang Baoliang;Qiu Longwei;Yang Yongqiang;Dong Daotao;Zhou Shibo;Liu Zhaowen;Bai Like(School of Geosciences,China University of Petroleum,Qingdao 266580,China;Key Laboratory of Deep Oil and Gas,China University of Petroleum,Qingdao 266580,China;Geophysical Research Institute,SINOPEC,Nanjing 211100,China;Dongxin Oil Production Plant,Shengli Oilfield Company,SINOPEC,Dongying 257061,China)

机构地区：[1]中国石油大学地球科学与技术学院,山东青岛266580 [2]中国石油大学深层油气重点实验室,山东青岛266580 [3]中国石化石油物探技术研究院,江苏南京211100 [4]中国石化胜利油田分公司东辛采油厂,山东东营257061

出　　处：《地球科学》2021年第9期3258-3277,共20页Earth Science

基　　金：国家科技重大专项(Nos.2017ZX05009⁃002,2017ZX05072⁃002);国家自然科学基金项目(No.41972099).

摘　　要：为探讨陆相断陷湖盆陡坡带构造活动控制下水下粗碎屑岩沉积特征、搬运机制及其演化规律,以滦平断陷盆地陡坡带下白垩统西瓜园组为研究对象,采用无人机倾斜摄影、实测剖面、砾石定向性定量表征等技术方法,从沉积背景、岩相类型、沉积单元及相序特征等方面开展野外露头解剖工作.滦平盆地西瓜园组沉积时期,近岸水下扇沉积于构造沉降速率大、湖平面上升、深水、古地貌陡峭环境,洪水携带粗碎屑沉积沿陡坡带入湖,底部发育与地震活动相关的砾质碎屑流,伴随发育滑动‒滑塌沉积,上部发育高密度浊流.随着沉积物不断供给,斜坡坡度逐渐减小;随着粗碎屑沉积搬运距离不断增加,砂砾质碎屑流中砾石表现出明显定向性,高密度浊流所占厚度比例增加;末端以低密度浊流为主.扇三角洲沉积于构造沉降速率相对较低、水深相对较浅、古地貌相对平缓的环境,发育相对成熟的供源体系,汇水系统长度较长,扇三角洲前缘粗碎屑岩由碎屑流向高密度浊流、牵引流、低密度浊流转换.In order to investigate the sedimentary characteristics,transport mechanism and evolution of the subaqueous coarse clastic rocks under the control of tectonic activity,this paper takes the Cretaceous Xiguayuan Formation in the Luanping rift basin as the study example.Technical methods,including UAV oblique photography,measured section,quantitative characterization of gravel orientation,and field outcrop anatomy were carried out from the sedimentary background,lithofacies,sedimentary units and facies association characteristics.During the Xiguayuan Formation of Luanping basin,the subaqueous fan developed in environments with high tectonic subsidence rates,rising lake level,deep water and steep palaeogeomorphology.Floods carried coarse clastic deposits along the steep slope into the lake,and its bottom developed gravelly debris flow associated with seismic activity,accompanied by sliding-slip sediments developed.The upper part is mainly composed of high-density turbidity currents.The slope gradient gradually decreases with the continuous supply of coarse clastic rocks.With the increasing transport distance of coarse debris deposits,the gravels in the bottom of gravelly debris flow show directionality and the thickness proportion of highdensity turbidity flow increases.The end part is dominated by low-density turbidity flow.The fan deltas developed in environments with relatively low tectonic subsidence rates,relatively shallow water and gentle palaeogeomorphology,and developed a relatively mature sediment delivery system.The catchment system is long,and the coarse clastic rocks transformed from clastic flow into high-density turbidity flow,traction current and low-density turbidity flow.

关 键 词：滦平盆地 陡坡带 西瓜园组 粗碎屑岩 近岸水下扇 扇三角洲 沉积特征 搬运机制 沉积学 

分 类 号：P618[天文地球—矿床学]