Furthermore , sorting of the sandstones in the braided river is better compared with that of in the meandering river system . in the same subfacies , grain size is larger and sorting is better in the channel sandstones which developed with large - scale cross - beddings such as trough cross - bedding , compared with sandstones in the flood microfacies . in the same microfacies , better sorting and coarser grained sandstones are distributed in the middle and lower part of the unit 与曲流河亚相相比，辫状河亚相砂岩的粒度较粗，分选性较好，砂体多次叠置而规模更大；相同河流亚相的河道微相与泛滥平原微相相比，前者的砂岩粒度较粗、分选性较好，发育槽状交错层理等大型层理构造；在同一微相内，处于中下部的流体单元其粒度较粗，分选较好。
During the early stage of middle permian , the studied area is dominant , from north to south , of alluvial fans , braided stream , braided delta plain , braided delta front and littoral deposits , while the extension of sedimentary facies belts in the middle and the late stage of middle permian is as the same as that of shanxi stage 中二叠世早期，研究区由北向南依次为冲积扇、辫状河、辫状河三角洲平原、辫状河三角洲前缘和滨浅湖所占据。中二叠世中晚期，沉积相带展布顺序与山西期相同。
The lake basin range was widen and the deep lake subfacies developed in the researched area during chang7 stage . the lake basin range contracted when it got to chang6 stage . consequently , the fan deltas , braided deltas , deltas , saucer lake and local deep lake facies developed in the area 长8期主要发育三角洲、扇三角洲及辫状河三角洲，而且以前缘亚相为主；进入长7期，湖盆范围扩大，研究区以深湖相为主；至长6期湖盆范围收缩，研究区发育扇三角洲、辫状河三角洲、三角洲、浅湖和局部的深湖沉积。
Based on the synthetic research of field outcrops , drilling section , well log and office compilation , combined with analyses of geological background , lithological association , sedimentary structure and palaeobiological character , the researched area in the chang6 - 8 oil - beds of triassic yanchang formation can be divided into deltas , braided deltas , fan deltas and lakes etc . four kinds of sedimentary facies 在野外露头、钻井剖面及测井曲线的综合研究和室内编图基础上，综合地质背景、岩性组合、沉积构造及古生物特征，研究区三叠系延长组长6 ? 8油层组被划分为三角洲、辫状河三角洲、扇三角洲及湖泊等4种沉积相类型。
The border facies did not appear at the south edge of tiaohu seg . in the basin , the braided river facies and braided delta facies were only found at the foot of chahaquan palaeohigh in the west - south edge of the basin , the meandering delta was found from mazhong structural belt to fangfangliang horseback , and the other area were found covered by the shallow and fairly deep lake facies 条湖凹陷南缘芦草沟组未见边缘相沉积；岔哈泉古隆起处见少量辫状河相及辫状河三角洲相沉积；方方梁凸起东部至马中构造带发育曲流河三角洲相；其余地区则均为滨浅?半深湖相沉积。
From sedimentology symbol such as rock assembled , sediment gradus , sandstone grading analysis , protogene sedimentary structure , ichnofossile and logging facies etc and palaeoenvironment background , it is confirmed that shen84 - an12block s34 segment is braid river delta system , not fan delta system ( abrupt slope ) . then it can be more partition as braid river delta plain sedimentary assembled , delta front sedimentary assembled and prodelta sedimentary assembled on core and log assembled . and delta plain sedimentary assembled can be identified four microfacies : braided distributary channel , crevasse splay , overbank deposits and interdistributary bay 沉积微相研究是储层非均质性研究的基础，研究区有丰富的岩芯资料和测井资料，通过岩石组合、沉积韵律，砂岩粒度分析、沉积构造、古生物遗迹和测井相等沉积学标志，结合古环境背景，确定沈84 ?安12块s _ 3 ~ 4段为辫状河三角洲体系，而不是前人所认为的扇三角洲(陡坡型)体系，在岩芯和测井组合上可进一步划分为辫状河三角洲平原沉积组合、三角洲前缘沉积组合和前三角洲沉积组合，其中三角洲平原沉积组合又可识别出辫状分流河道、决口扇、分流河道边部和分流间湾四种微相类型；三角洲前缘沉积组合识别出水下分流河道、水下分流河道边部和分流河口坝三种微相。
The analyses of the sedimentary facies , rock geochemistry and reformation after the sedimentation from the upper cretaceous quantou formation to nenjiang formation indicate that the beneficial sand - bodies of the uranium deposit are mainly quantou formation ' s braided channel and qingshankou formation ' s delta sandstone types 摘要从上白垩统泉头组嫩江组沉积相展布、岩石地球化学及沉积期后改造作用分析入手，阐明了研究区有利铀成矿砂体主要为泉头组的辫状河与青山口组的三角洲砂体。
Based on the synthetic research of field outcrops , drilling section , well log and office compilation , combined with analyses of geological background , lithological association , sedimentary texture , sedimentary structure , geochemical and palaeobiological features , the researched area in the palaeozoic can be divided into deltas , braided deltas , lacus , barrier coast , continental shelf and carbonate platform etc . six kinds of sedimentary facies 在野外露头、钻井剖面及测井曲线的综合研究和室内编图基础上，综合地质背景、岩性组合、沉积结构、沉积构造、地球化学及古生物学特征，研究区古生界被划分为三角洲、辫状河三角洲、湖泊、障壁海岸、陆棚及碳酸盐台地等6种沉积相类型。
This result lays a solid foundation for the research . 2 . based on the study of petrology facies , facies association and sedimentary sequences , the sedimentary processes and systems are established . they consist of debris and hyper concentration flow deposits , channel deposit of braided and meandering streams , and alluvial fans , floodplains , fan - deltas and lacustrine turbidities 根据岩相、相组合以及沉积层序的研究，确立了研究区的沉积作用类型和沉积体系，它们包括碎屑流和超浓缩洪流沉积、辫状河河道沉积，以及冲积扇沉积、洪泛平原沉积、扇三角洲沉积和湖相浊流沉积。
