【作者】 张峰；

【导师】 陈洪德；

【作者基本信息】 成都理工大学 ， 沉积学， 2011， 博士

【摘要】 本论文以四川盆地东北部(川东北地区)上三叠统须家河组为研究对象,以沉积学,层序地层学,古生物学,地球化学和地球物理学等学科理论为指导,对野外露头、钻井岩心、测井资料、地震资料、薄片进行了综合分析；论文研究了川东北地区须家河组地层的岩石学特征、物质来源、沉积体系特征及层序地层特征,在此基础上,以三级层序或三级层序体系域为编图单元,编制具有精确性、等时性、成因连续性等优点的岩相古地理图,探讨了该区层序岩相古地理特征及演化规律。主要内容及成果如下：1.在前人研究基础上,结合本次研究,研究区内须家河组共划分出五个岩性段,分别为须一段、须二段、须三段、须四段、须五段；大量的薄片鉴定结果表明,研究区内须家河组共发育陆源沉积岩、混积岩和特殊岩石类型3大类,并总结出了14种陆源沉积岩类；2.在岩石组份(砂岩碎屑、岩屑成分、砾石成分)分析基础上,结合重矿物组合特征分析,认为须家河组具双物源的特征：一为西北方向的龙门山地区,另一个为东北方向的古大巴山地区。须一至须五期物源的演化与造山带的活动息息相关。随着龙门山造山带的构造隆升,研究区受龙门山造山带的影响越来越大。3.通过研究区地表剖面和钻井资料的分析研究,依据岩石颜色、岩石结构、沉积构造及古生物化石等沉积学标志和不同测井曲线特征标志,在川东北地区须家河组沉积演化中识别出了3个沉积体系组：大陆体系组、海陆过渡体系组及海洋体系组,包括5个沉积体系；其中,1)大陆体系组：主要包括冲积扇沉积体系、湖泊沉积体系、湖泊三角洲沉积体系；2)海陆过渡体系组：主要为三角洲沉积体系；3)海洋体系组：主要有海岸沉积体系,并总结了出海陆过渡三角洲、陆相冲积扇—湖泊二种沉积模式特征。4.通过野外露头与钻井岩心观测,将野外剖面和钻井进行了系统的地层划分与对比。进行了层序界面类型和划分标志研究,识别出了六种层序界面：不整合面、古风化壳、大型底冲刷面、间歇暴露面、岩性岩相转换面及最大(海)湖泛面；厘定了研究区上三叠统须家河组层序地层划分方案,并划分为3个构造层序,5个三级层序。5.以三级层序体系域或三级层序为编图单元,对研究区进行了岩相古地理编图研究,共编制了6张层序岩相古地理图(SQ1、SQ2HST、SQ2TST、SQ3、SQ4、SQ5),揭示了区域岩相古地理特征及演化规律,研究表明：SQl期,研究区受海侵影响较大,经历了海相—陆相的沉积环境；SQ2期,海水完全退出研究区,为陆相沉积环境,主要为一套三角洲的砂岩沉积；SQ3期,由于研究区周缘造山带构造活动的减弱,物源供给有限,工区内主要为一套薄的泥页岩,由北至南依次为冲积三角洲平原亚相、三角洲前缘亚相、浅湖亚相的沉积环境；SQ4期,伴随着盆缘造山带构造活动的加强,研究区由北至南呈现出冲积扇—冲积三角洲的沉积特征；SQ5期,盆缘造山带构造活动减弱,由北至南表现为三角洲平原亚相过渡至三角洲前缘亚相的沉积特征。更多还原

【Abstract】 This thesis used The Xujiahe Formation of Upper Triassic in northeast Sichuan basin(northeastern region) as the research object,and the principle of Sedimentology, Sequence Stratigraphy, Geochemistry, Paleontology,Geophysics and some other traditional geology theories were used as the instructions of this paper during the integrated researching of outcrops, cores,logging data,seismic data and slice.This article analyzed characteristics of rock, material source,the charaters of depositional system and sequence stratigraphy of The Xujiahe Formation in northeast Sichuan basin.On this basis analysis, we used the third-order sequences or tertiary sequence system tracts as the mapping unit to draw the sequence-based lithofacies paleogeography map with the charateristics of scientifically, isochronously, continuously and precisely.We explored sequence lithofacies paleogeography and evolution in this area also. Main contents and results are as follows:1. Based on previous studies and combined with this study, the Xujiahe Formation of the study area was divided into five lithologic:first member、second member、third member、fifth member of Xujiahe Formation;A large number of The thin section results show that the Xujiahe Formation in study area were developed 3 rock type:terrestrial sedimentary rocks, mixed sedimentary rocks and special categories, and summed up the class of 14 terrestrial sedimentary rocks;2.Based on the analysis of Component in the rock (sandstone debris, debris composition, gravel component) and combined with the characteristics of heavy mineral assemblages, we believed that Xujiahe Formation with characteristics of dual source:one is Longmen Shan region which is northwest to study area, the other is of the ancient Daba region which is northeast to study area. The evolution of Material source was closely related with the orogenic activity during the first member time to fifth member time of Xujiahe Formationt.With the construction of Longmen Mountain orogenic uplift,the study area was influenced by Longmen Shan orogenic belt more and more.3. By studying of surface profiles and drilling data analysis,and according to the different curve feature flags and sedimentary features:the color of rock,rock structures, sedimentary structures,fossils and so on,we identified three depositional systems group druing the sedimentary evolution of Xujiahe Formation in northeastern Sichuan: Continental System group,Sea-land transition system group and marine systems group of groups, including five depositional system; where 1) Continental System group:alluvial fan, river depositional system, Lacustrine depositional system,Lake-delta system; 2) sea-land transition system group:delta system; 3) group of marine systems:coastal depositional system,and summarizes two kinds of sediment mode characteristics:the transition of delta land to sea and continental alluvial fan -lake.4. according to outcrop and drilling cores,the outcrops and drilling is carried out a systematic stratigraphic division and contrast. After research on the types of sequence boundary and classification standard, six kinds of sequence boundaries are identified: Surface of unconformity, weathering crust, large-scale scour the bottom surface, intermittently exposed surfaces, lithologic facies transition and maximum surface (sea) flooding surface.Sequence stratigraphy division plan of Upper Triassic is setted, the Xujiahe Formation can be divided into 3 Structural sequences and 5 third-order sequences.5. we used the third-order sequences or tertiary sequence system tracts as the mapping unit to draw the sequence-based lithofacies paleogeography map,and drawed six sequence-based lithofacies-paleogeography maps(SQ、SQ2HST、SQ2TST. SQ3、SQ4、SQ5) that showed the evolution and features of regional lithofacies paleogeography. The results show that:in SQ1,study area through the marine terrestrial sedimentary environment and was influenced largely by the transgression;In SQ2, Sea completely withdrew from the study area that was continental sedimentary environment and a delta of sand deposition mainly;In SQ3, because of declining of orogenic tectonic activity surrounding the study area, source supply is limited, the study area deposit a thin shale with the sedimentary environment characteristics of shallow lakes.In SQ4, with the strengthening of basin margin orogenic tectonic activities, the study area showed the sedimentary characteristics of Alluvial Fan - Alluvial Delta from north to south;In SQ5, with the declining of basin margin orogenic tectonic activities, the sedimentary environment of the study area were much the same as SQ3 period.更多还原