摘要
通过野外实测剖面和镜下薄片观察,川西汉旺地区雷口坡组四段发育典型的风暴岩,具有底冲刷—充填构造、风暴砾屑层、菊花构造和丘状交错层理等典型风暴沉积标志。根据该风暴岩岩性、沉积位置、沉积标志组合特征,共识别出三种风暴沉积序列类型:1)序列Ⅰ由侵蚀底面及砾屑段、粒序段组成,代表靠近风暴浪基面附近的台前缓斜坡下部环境; 2)序列Ⅱ由侵蚀底面及砾屑段、粒序段、平行纹层段、丘状纹层段组成,代表靠近正常浪基面附近的台前缓斜坡上部环境; 3)序列Ⅲ由粒序段、平行纹层段组成,代表台地边缘环境。风暴层序自下而上的沉积演化为:台前缓斜坡下部—台前缓斜坡上部—台地边缘,整体为一个向上变浅的沉积序列。
On the basis of outcrop and thin section analyses,tempestites were identified in the fourth member of the Leikoupo Formation,Hanwang area,western Sichuan Basin.The major markers of storm sediments are scouring fill structures,storm-flow-generated gravelstones,chrysanthemum-like structures and hummocky cross-stratifications(HCS)etc.Three types of storm-deposited sequence were observed,in terms of their lithology,sedimentary position and depositional marks.Type I consists of storm gravelstone and graded members deposited at the lowest part of slopes near the storm wave base.Type II contains a storm gravelstone member,a graded member,a parallel lamination member and an HCS,which is deposited at the uppermost part of the slope near the fine-weather wave base.Type III comprises a graded member and a parallel lamination member,deposited at the platform margin.The depositional evolution of the tempestites shallows upward from the base of the slope to the upper part of the slope at the platform margin.The discovery of tempesites in the study area is highly significant in understanding paleolatitude and paleoplate evolution,paleoclimate change,stratigraphic isochronous contrast,and the sedimentary environment of the Sichuan Basin during the Middle Triassic,particularly the development of the Longmenshan island chain in the Songpan-Ganzi Sea.
作者
赵聪
刘树根
宋金民
唐玄
赖冬
ZHAO Cong;LIU ShuGen;SONG JinMin;TANG Xuan;LAI Dong(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2019年第1期94-103,共10页
Acta Sedimentologica Sinica
基金
国家科技重大专项(2017ZX05005003-007)~~
关键词
川西
汉旺
雷口坡组
风暴岩
地质意义
沉积环境
western Sichuan Basin
Hanwang
Leikoupo Formation
tempestites
geological significances
depositional environment
