川西南荥经坳陷川荥页1井奥陶系沉积相与古生物特征及地层厘定  

Sedimentary facies, paleontological characteristics and stratigraphic delineation of the Ordovician strata through the CYY1 well in the Yingjing depression,southwestern Sichuan

作　　者：熊小辉[1,2] 王剑 汪正江[1,2] 熊国庆 邓奇[1,2] 杨平 XIONG Xiao-hui;WANG Jian;WANG Zheng-jiang;XIONG Guo-qing;DENG Qi;YANG Ping(Chengdu Center,China Geological Survey,Chengdu 610081,Sichuan,China;Key Laboratory of Sedimentary Basins and Oil and Gas Resources,Ministry of Natural Resources,Chengdu 610081,Sichuan,China;Chengdu University of Technology,Chengdu 610059,Sichuan,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081 [2]自然资源部沉积盆地与油气资源重点实验室,四川成都610081 [3]成都理工大学,四川成都610059

出　　处：《沉积与特提斯地质》2018年第3期16-24,共9页Sedimentary Geology and Tethyan Geology

基　　金：四川盆地龙马溪组页岩气战略选取调查(DD20160193);四川盆地下古生界海相页岩气基础地质调查项目(基金项目编号41402103)

摘　　要：对川西南荥经坳陷内三口页岩气井尤其是川荥页1井奥陶系开展了系统的岩心观察和分析。三口钻井在梁山组之下均发育十余米厚的灰黑色泥岩,其中川荥页1井灰黑色泥岩厚近16m。沉积相分析认为灰黑色泥岩为浅水陆棚相,泥岩之下发育的大套砂岩为滨岸近滨亚相,总体向上海水逐渐变深。砂岩中发育丰富的沉积软变形构造及波状交错层理、浪成沙纹层理、平行层理、斜层理等构造。川荥页1井上部泥岩中见大量三叶虫、笔石和腕足等化石及其碎片,鉴定表明含有代表中下奥陶统的常见生物分子,如对笔石(Didymograotus sp.)、大洪山虫(Taihungshania sp.)等。该套砂泥岩组合在沉积相及古生物化石等方面明显区别于荥经坳陷周缘奥陶系五峰组—志留系龙马溪组,与研究区及邻区中下奥陶统红石崖组、湄潭组、大湾组、大官山组中段等层位相当。A systematic core observation and analysis are carried out for the Ordovician strata through three wells,especially through the CYY1 well in the Yingjing depression,southwestern Sichuan.Below the Permian Liangshan Formation through the three wells,a succession of greyish black mudstones is developed,with a thickness of more than 10 m(16 m thick in the CYY1 well),and assigned to the shallow shelf facies.Then the nearshore sandstones are found below the greyish black mudstones in the shallow shelf facies,with some siltstone strips or lens interbedded,displaying an overall deepening-upward sequence.In the sandstones and siltstones of nearshore facies,there occur abundant sedimentary structures including wavy cross bedding,wave-built cross bedding,parallel bedding,oblique bedding,as well as plenty of soft-sediment deformational structures.In the upper greyish black mudstones through the CYY1 well,there occur numerous fossils and fossil fragments of trilobite,graptolite and brachiopods.In addition,there are also the Middle-Lower Ordovician members such as Didymograotus sp.and Taihungshania sp.The above-mentioned sandstone-mudstone successions are highly different in sedimentary facies and fossil from those in the Ordovician-Silurian Wufeng Formation and Longmaxi Formation around the Yingjing depression,but correspond with the stratigraphic horizons of the Middle-Lower Ordovician Hongshiya Formation,Meitan Formation,Dawan Formation and the middle member of the Daguanshan Formation.

关 键 词：川荥页1井 中下奥陶统 沉积相 古生物特征 荥经坳陷 

分 类 号：P534.42[天文地球—古生物学与地层学]