四川类前陆盆地上三叠统须家河组沉积体系  

Sedimentary system of the Upper Triassic Xujiahe Formation in the Sichuan forelandoid basin

作　　者：郑荣才[1] 戴朝成[1] 罗清林[2] 汪小平[3] 雷光明[2] 蒋昊[3] 陈虎[3] 

机构地区：[1]"油气藏地质及开发工程"国家重点实验室.成都理工大学 [2]川庆钻探工程有限公司地质勘探开发研究院 [3]中国石油西南油气田公司重庆气矿

出　　处：《天然气工业》2011年第9期16-24,132-133,共9页Natural Gas Industry

基　　金：国家科技重大专项"四川盆地岩性油气藏富集规律与目标评价"(编号:2011ZX05001-005)

摘　　要：近期的研究成果表明,对四川盆地上三叠统须家河组沉积相类型的认识存在很大分歧,主要有3种观点:①冲积扇、扇三角洲、河流、湖泊三角洲、湖泊—沼泽等沉积体系的多类型;②湖泊滩坝沉积相;③浅海潮汐砂坝沉积相。为此,根据多年野外地质调查、室内研究成果,再次坚持和论证了须家河组为多类型陆相沉积体系复合体的传统认识。具体证据如下:在对地表剖面和钻井岩心精细沉积相分析的基础上,结合粒度分析和测井资料,可从四川类前陆盆地上三叠统须家河组中识别出冲积扇、河流、扇三角洲、湖泊三角洲、湖泊—沼泽等沉积体系。在川西坳陷、川东北坳陷和川东南坳陷围限川中前陆隆起的"三坳围一隆"构造—沉积格局中,各沉积体系展布各具特色,规律为:沿龙门山和米仓山—大巴山造山带前缘为冲积扇或扇三角洲沉积体系发育带;围绕川西、川东北和川东南坳陷带为湖泊—沼泽沉积体系发育带;盆地中心的川中前陆隆起为河流、三角洲—湖泊沉积体系发育带。结论认为:受"三坳围一隆"构造—沉积格局控制的冲积扇、扇三角洲、河流、湖泊三角洲和湖泊—沼泽等多元相沉积体系在时空中有规律的组合、展布和演化,应该是解释须家河组沉积相特征更可靠的答案。Recent research results reveal that much controversy exists upon the types of sedimentary facies of the Upper Triassic Xujiahe Formation in the Sichuan Basin:a composite sedimentary system consisting of various sedimentary facies including(1)alluvial fans,fan deltas,fluvial and lacustrine deltas,and lacustrine-swamps;(2)lacustrine beach/bar facies;and(3)shallow marine tidal sand bar facies.Based on outcrop observation and laboratory research achievements over the years,the correctness of traditional understanding,i.e.,a composite sedimentary system consisting of various types of continental deposits in the study area,is again verified by a detailed analysis of sedimentary facies of outcrops and cores in combination with grain-size analysis data and logging interpretation.Within the tectonic-sedimentary framework of 'Three Depressions Surrounding One Uplift',i.e.the western,northeastern and southeastern Sichuan depressions surrounding the central Sichuan foreland uplift,the distribution of each sedimentary system shows distinctive features.The alluvial fans/fan deltas develop along the Longmenshan and Micangshan and Dabashan structural belt front.The lacustrine-swamp sedimentary system develops in the said three depressions.The fluvial,delta-lacstrine sedimentary systems occur in the central Sichuan uplift.Thus,it is concluded that the Upper Triassic Xujiahe Formation in the Sichuan Basin has a composite sedimentary system consisting of alluvial fans,fan deltas,fluvial and lacustrine deltas,and lacustrine-swamp facies.

关 键 词：四川类前陆盆地 晚三叠世 须家河组 古构造格局 沉积体系 沉积相 测井解释 粒度分析 

分 类 号：P618.13[天文地球—矿床学] P512.2[天文地球—地质学]