【作者】 程立雪；

【导师】 陈洪德； 侯明才；

【作者基本信息】 成都理工大学 ， 地质学， 2011， 硕士

【摘要】 本文采用沉积学、岩石学、层序地层学、测井以及地震等多学科相结合的方法与手段,研究了广元地区上三叠统须家河组沉积体系,分析了沉积特征。对广元工农镇露头剖面进行了层序地层学研究,并建立了区域层序地层格架,进而以三级层序为基础,分析了广元—元坝地区的层序—岩相古地理特征及演化,具体步骤及成果如下:首先在收集众多前人资料基础上,通过对广元地区上三叠统须家河组露头剖面、钻井岩心和大量测井资料的观察、分析、研究,提取出岩石学特征、沉积构造、电测曲线、剖面结构以及粒度特征等沉积相标志,从上三叠统须家河组中划分出冲积扇、河流、湖泊三角洲、湖泊、海相三角洲和有障壁海岸等6个沉积体系,详细描述和综合归纳了各沉积体系及其沉积亚相和微相的特征。并进一步得出了2种相应的沉积模式,须家河组一段至二段主要为海陆过渡相→海相的沉积模式,由海相三角洲、海湾、障壁海岸与浅海组合。须家河组三段至五段总体上发育由盆地边缘冲积扇经河流到三角洲或扇三角洲再到湖泊的沉积模式,随盆地的时空变化而有所变化,可细分为两种沉积模式,即(1)冲积扇→辨状河三角洲→湖泊的模式和(2)冲积扇→扇三角洲→湖泊的模式。运用陆相层序地层学的方法对研究区须家河组进行了层序地层学研究。以不整合面为界限确定了层序界面,将广元地区须家河组划分出3个构造层序(TS1、TS2和TS3)和5个三级层序(SQ1、SQ2、SQ3、SQ4和SQ5),SQ1对应TS1,SQ2和SQ3对应TS2,SQ4和SQ5对应TS3。须5段对应的层序SQ5由于龙门山隆升作用所以在广元工农镇地区缺失,深入探讨了层序特征。并建立了广元工农镇—元坝地区的南北向的层序地层对比格架。以Ⅲ级层序为编图单元,根据研究区内重点钻井沉积相的划分,编制了广元—元坝地区上三叠统须家河组层序-岩相古地理图,详细描述了各期层序岩相古地理特征及其演化。更多还原

【Abstract】 This artiele uses sedimentology, sequenee stratigraphy, petrology, logging, seismie and combination of mult-disciplinary to reseach sedimentary features and analyze the deposition types of the Xujiahe formation of the Upper Triassic Series in Guangyuan area. It reserches the sequence stratigraphy of outcropping profile, then establishing sequence stratigraphic framework and further based on depositional sequence analyzes sequence-based lithofacies palaeogeographic features of Guangyuan to Yuanba area, concrete steps and results are as follows:Firstly, On the basis of lots of forerunners’data and my research in this thesis, Combining drilling data with observation and analysis of the well core, Xujiahe formation can be divided into six kinds of sedimentary systems such as alluvial fan, river, lake delta, lake, marine delta and beach-barrier by using sedimentary facies signs which is rock feature, sedimentary structure, well log and section texture, Each of the sedimentary systems was subdivided into several subfacies and microfacies, which were described and generalized in detail. By generalizing, I conclude that two relevant sedimentation model of Guangyuan area to Yuanba area. The first sedimentation model is transitional facies- marine facies in Xujiahe formation one-two section, which is made up of marine delta, bay, beach-barrier and epeiric sea. The second sedimentation model is alluvial fan-river-delta or fan delta-lake in Xujiahe formation three-five section, which is changed along with the time and space alter of basin. Further, it can be subdivided into two sedimentation model. The one: alluvial fan-river(alluvial plain)-braid river delta-lake. The second: alluvial fan-fan delta-lake.On the basis of analysis on seismic sequence, defining the stratic interface by the surface of unconformity, this paper divids the Xujiahe Formation of outcropping cut plane in Guangyuan Gongnong town into three tectonic sequence and five sedimentary sequence, and also deeply investigates the characteristics of all levels sequence. It establishes sequence stratigraphic framework of the Xujiahe Formation of the Upper Triassic in Guangyuan Gongnong town to Yuanba area.The sequence-based lithofacies-paleogeographic maps of the Xujiahe Formation of the Upper Triassic in study area are compiled by choosing sedimentary sequence as the isochronous mapping unit. This paper demonstrats in details the characteristics of lithofacies aleogeography and their evolution during different sedimentary sequence developing period.更多还原