六盘山盆地及周缘下白垩统沉积体系研究

发布时间：2018-04-22 01:18

本文选题：六盘山盆地 + 下白垩统　；参考：《西北大学》2015年硕士论文

【摘要】：通过露头及岩心、原始沉积构造、岩性、地化指标、物源方向等特征,结合测井及地震相分析,重新厘定地层年代、进行区域地层划分及对比,从点、线到面,编制沉积相单并柱状图、典型剖面柱状图、连井剖面对比图和沉积相与砂体平面展布图,开展沉积相类型及其分布特征研究,进行物源分析,并对物源区进行探讨,研究和划分沉积体系和沉积相及砂体展布特征,建立研究区下白垩统沉积模式。研究区下白垩统主要发育六盘山群,地层从老到新划分为五组分别是：三桥组、和尚铺组、李洼峡组、马东山组及乃家河组,厚度较发育,可达3000多米,六盘山群的岩性、沉积相主要发育有冲积扇相的砾岩,过渡到三角洲相的砂岩,最后为湖泊相的泥质灰岩,三者之间的沉积演化连续发育,与下伏、上覆的地层均表现为角度不整合接触。对主要基岩特征、古流向分析和砾石的研究,发现研究区主要受东南部、西北部及东北部三个方向的物源控制,推测东南部物源来源于祁连-秦岭造山带和华北地台,西北部物源来自于北祁连地块,东北部物源主要来自于华北地台。将研究区下白垩统主要划分为四种沉积体系,分别是冲积扇沉积体系、河流沉积体系、辫状河三角洲沉积体系和湖泊沉积体系。三桥组沉积期以冲积扇相沉积为主,和尚铺期以河流相沉积为主,李洼峡期己演变为辫状河三角洲和滨浅湖相沉积,马东山期湖泊发育到鼎盛时期,以滨浅湖相和半深湖相沉积为主,乃家河期为湖泊衰亡期,湖泊面积萎缩,以半深湖相沉积为主。
[Abstract]:Through the features of outcrop and core, original sedimentary structure, lithology, geochemistry index and source direction, the stratigraphic age is redefined in combination with logging and seismic facies analysis, and regional stratigraphic division and comparison are redefined, from point, line to surface, sedimentary facies single and histogram, typical section histogram, cross section contrast diagram and sedimentary facies and sand body plane distribution The types and distribution characteristics of sedimentary facies are carried out, the source analysis is carried out, and the source area is discussed, the sedimentary system and the sedimentary facies and sand body distribution characteristics are divided, and the lower Cretaceous sedimentary model is established in the study area. The lower Cretaceous in the lower Cretaceous area is mainly developed by the six Panshan group, and the strata are divided from the old to the new to the three bridge groups, respectively. The thickness of the Liupu group, the Liupu Xia formation, the mdongshan formation and the najiahe formation is more than 3000 meters, and the lithology of the six Panshan group is mainly developed with the conglomerate of alluvial fan facies, transition to the sandstone of the delta facies, and the muddy limestone of the lake facies. The sedimentary evolution between the three is continuously developed, which is manifested as the underlying and overlying strata. The main bedrock characteristics, paleo flow analysis and gravel study found that the study area was mainly controlled by three directions in the southeast, northwest and northeastern parts. The southeastern source was derived from the Qilian Qinling Mountains orogenic belt and the North China platform. The north-west source was derived from the North Qilian block, and the Northeast was mainly derived from the northeast. The lower Cretaceous of the North China platform is divided into four sedimentary systems, namely alluvial fan depositional system, river sedimentary system, braided river delta sedimentary system and lake depositional system. The sedimentary period of the Sanqiao group is alluvial fan facies, and the phase is mainly river facies sedimentation, and the Li depression stage has evolved into a braided river delta. The lake facies and shallow lake facies deposit, the Ma Dongshan Lake developed to the heyday period, mainly with the shallow lake facies and the semi deep lacustrine facies deposit. The lake period is the decline period of the lake, the lake area atrophy and the semi deep lacustrine facies deposit is the main deposit.

【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P534.53

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