伏龙泉断陷断坳转换期层序地层与沉积体系特征

发布时间：2018-02-24 11:05

本文关键词： 断坳转换层序地层沉积体系伏龙泉断陷　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：伏龙泉断陷位于松辽盆地南部,处于中央凹陷区与东南隆起区的交界带上,断陷面积约1000km2,最大埋深5000m,自白垩纪以来经历了多个构造演化阶段,具有断、坳双重结构。登娄库组沉积时期为断—坳转换期,断层活动减弱至消亡,早期同沉积断层对沉积仍有控制作用,边界断层限制东部沉积范围;晚期盆地进入坳陷时期,同沉积断层活动性逐渐减弱至消失,沉积范围变大。登娄库组厚度整体呈东厚西薄、北厚南薄的展布特征,最大沉积厚度超过700m。在登娄库组层序地层研究方面,识别出T4、T3两个二级层序界面及T-3m一个三级层序界面,将登娄库组划分为SQ1和SQ2两个三级层序,SQ1层序识别和划分低位域、水进域和高位域三种体系域,SQ2层序识别和划分出水进域和高位域两种体系域。研究了各三级层序在平面上的展布特征和规模,建立了垂向上由断陷向坳陷转换、平面上由受断层控制到超越断层边界展布、沉积充填上由河流三角洲向河流相沉积转换的层序地层模式。针对研究区钻井和取芯较少且极不均一的难题,论文恢复了登娄库组沉积前期的古地貌,发现登娄库组沉积以前盆地存在南北两个主要沉积中心,早期SQ1时期砂地比环洼分布,泥岩颜色在洼陷中心呈深灰色、灰色,斜坡和凸起呈棕红色、紫色,认为该时期盆地存在东部、东南部、南部、西南、西部五个主要物源方向,晚期SQ2砂地比呈区域性连片分布,泥岩颜色主要为棕红色、棕褐色等氧化色,认为该时期物源方向主要以东部为主。论文结合10口取芯井和33口井的录井、测井及三维地震等资料,在松辽盆地伏龙泉断陷登娄库组识别出4种沉积相、6种亚相及10种微相。登娄库组早期主要发育辫状河三角洲—湖相沉积体系,西部缓坡带和东部陡坡带以辫状河三角洲前缘沉积为主,北部永安洼陷区发育半深湖与滑塌沉积,南部伏南洼陷发育浅湖沉积和滑塌扇沉积。中期湖盆萎缩,伏北洼陷区以辫状河三角洲前缘和浅湖相为主。伏南洼陷湖泊消失,以辫状河三角洲前缘—平原为主。晚期东部边界断层控沉积作用明显减弱,湖盆面积急剧萎缩,经过填平补齐作用,已经转换为辫状河三角洲平原—辫状河沉积体系。
[Abstract]:The Fulongquan fault depression is located in the southern part of Songliao Basin. It is located at the junction zone between the central depression and the southeast uplift area. The fault depression covers an area of about 1000km2, with a maximum buried depth of 5000m. It has undergone several tectonic evolution stages since the Cretaceous period and is faulted. The depositional period of Denglooku formation is fault-depression transition period, the fault activity decreases to extinction, the early synsedimentary fault still controls the deposition, the boundary fault restricts the eastern sedimentary range, and the late basin enters the depression period. The activity of synsedimentary faults gradually decreases to disappear, and the sedimentary range becomes larger. The thickness of Dengloku formation is as a whole thick and thin in the east and west, and the thickness in the north is more than 700 m.The maximum thickness of the deposit is more than 700 m. In the study of sequence stratigraphy of the Denglooku formation, Two second-order sequence interfaces of T _ 4N _ 3 and T _ 3m are identified, and Denglooku formation is divided into SQ1 and SQ2 _ 3 sequence SQ1 sequences. The SQ2 sequences of three system tracts are identified and divided into two systems tracts. The distribution characteristics and scale of each third-order sequence on the plane are studied, and the vertical transition from fault to depression is established. The sequence stratigraphic model of fluvial delta to fluvial sedimentary transformation on the plane from fault controlled to outspread fault boundary is filled. In view of the problem that drilling and coring are few and very uneven in the study area, The paleogeomorphology of Denglouku formation was restored in this paper. It was found that there were two main sedimentary centers of north and south in the basin before the deposit of Denglouku formation. In the early SQ1 period, the sand and land were distributed in Bihuan depression, and the color of mudstone was dark gray and gray in the center of sag. The slope and bulge are brownish red and purple. It is believed that there are five main provenances in the basin in the east, southeast, south, southwest and west of the basin. In the late period, the SQ2 sandfield ratio was distributed in a regional sequence, and the mudstone color was mainly brownish red. The source direction of this period is mainly in the east. This paper combines the logging, logging and 3D seismic data of 10 coring wells and 33 wells. Four sedimentary facies, 6 subfacies and 10 microfacies were identified in Dengloku formation of Fulongquan fault depression in Songliao Basin. The braided river delta-lacustrine sedimentary system was mainly developed in the early stage of Denglouku formation. The west gentle slope belt and the eastern steep slope belt are mainly composed of braided river delta front sediments, the north Yongan sag develops semi-deep lake and slump deposits, the southern Funan sag develops shallow lake deposits and sloughing fan deposits, and the lake basin shrinks in the middle period. In Fubei depression, braided river delta front and shallow lacustrine facies are dominant. The lake in Funan sag disappears, and braided river delta fore-plain is the main one. In the late period, the fault-controlled sedimentation of the eastern boundary is obviously weakened, and the lake basin area shrinks sharply. It has been transformed into braided river delta plain-braided river sedimentary system.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P539.2;P618.13

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