川西地区雷口坡组风暴沉积特征及其地质意义  

Sedimentary Characteristics and Geological Significance of Tempestites in the Leikoupo Formation,Western Sichuan Basin

作　　者：冯宇翔 宋金民[1,2] 刘树根[1,3] 杨迪 李智武[1] 金鑫[1,2] 范建平[1,2] 王佳蕊 FENG YuXiang;SONG JinMin;LIU ShuGen;YANG Di;LI ZhiWu;JIN Xin;FAN JianPing;WANG JiaRui(State Key Laboratory of Oil and Gas Reservoir Geology and Exploration,Chengdu University of Technology,Chengdu 610059,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China;Xihua University,Chengdu 610039,China)

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),成都610059 [2]成都理工大学能源学院,成都610059 [3]西华大学,成都610039

出　　处：《沉积学报》2023年第3期661-672,共12页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41872150);中国石油西南油气田公司四川盆地沉积与岩相古地理研究中心项目(JS2020-039)。

摘　　要：中三叠世扬子地台西缘风暴频发,风暴岩较发育。根据剖面实测和薄片观察,对川西中三叠系雷口坡组典型的风暴沉积特征进行了研究。川西地区发育底冲刷面、砾屑段、粒序段和丘状交错层理等构造,可划分出7种风暴序列:序列Ⅰ主要由底冲刷面及砾屑段(A)、粒序段(B)、平行层理段(C)构成,主要受风暴涡流控制,形成于正常浪基面与风暴浪基面之间;序列Ⅱ主要由底冲刷面及砾屑段(A)、粒序段(B)、平行层理段(C)、风暴浊积段(E1)构成,主要受风暴回流控制,形成于风暴浪基面以上,近风暴浪基面;序列Ⅲ主要由底冲刷面及砾屑段(A)、粒序段(B)构成,主要受风暴回流控制,形成于浪基面与风暴浪基面之间;序列Ⅳ主要由底冲刷面及砾屑段(A)、粒序段(B)、平行层理段(C)、丘状交错层理段(D)构成,主要受风暴涡流控制,形成于暴浪基面与正常浪基面间的较浅水区;序列Ⅴ主要由粒序段(B)、平行层理段(C)构成,主要受风暴涡流控制,处于正常浪基面之上;序列Ⅵ主要由砾屑段(A)构成,主要受风暴潮流控制,发育于正常浪基面上;序列Ⅶ主要由粒序段(B)和泥晶灰岩段(E2)构成,主要受风暴浊流控制,形成于风暴浪基面附近。风暴岩的发育,一是表明上扬子地区雷口坡时期处于低纬度地区,证明川西地处台缘—斜坡地带,约束了当时的古纬度及古地理格局;二是证实了龙门山古隆起与川西斜坡形成的古海湾的存在;三是约束了古海岸线的方位,进而指示微生物岩的北东—南西向带状展布特征。In the Middle Triassic,the western margin of the Yangtze Platform experienced frequent hurricanes,and tempestites were developed as a result.The typical storm sedimentary characteristics of the Middle Triassic Leikopo Formation in the western Sichuan Basin were analyzed in this study from a profile survey and microscopic observations.Major storm deposit sedimentary structures were recognized(scouring-fill structures,storm-generated gravelstones,rip-up clasts,graded bedding and hummocky cross-bedding,etc.).Seven types of tempestite sequences were developed:Type I sequence consists of bottom scouring surface with storm-generated gravel bedding(A),graded bedding(B),and parallel bedding(C),mainly generated by the storm vortex and deposited between the normal wave base and the storm wave base.Type II sequence consists of bottom scouring surface with storm-generated gravel bedding(A),graded bedding(B),parallel bedding(C) and a storm turbidite layer(E1),mainly caused by storm inverse flow,and evident above and near the storm wave base.Type III sequence comprises bottom scouring surface with storm-generated gravel bedding(A) and graded bedding(B),mainly the result of storm inverse flow,appearing between normal-and storm wave base.Type IV sequence consists of bottom scouring surface with storm-generated gravel bedding(A),graded bedding(B),parallel bedding(C) and hummocky cross-bedding(E),mainly caused by the storm vortex and formed in the shallow water area between the storm wave base and normal wave base.Type V sequence consists of graded bedding(B) and parallel bedding(C),mainly caused by the storm vortex and formed above the normal wave base.Type VI sequence consists of storm-generated gravel bedding(A),mainly the result of storm tides and formed above the normal wave base.Type VII sequence consists of graded bedding(B) and micritic limestone(E2),mainly from storm turbidity current,formed near the storm wave base.The discovery of the tempestites confirms that the Leikoupo period in the upper Yangtze region was in a low

关 键 词：川西地区 雷口坡组 风暴沉积 古海岸线 古海湾 

分 类 号：P512.2[天文地球—地质学]