四川广元羊木—岩洞地区震旦纪—寒武纪界线地层序列及构造-沉积演化
Stratigraphic sequence and tectonic-sedimentary evolution of Sinian-Cambrian boundary in Yangmu-Yandong area,Guangyuan,Sichuan Province
王林康 1文龙 2李智武 3刘树根 4陈代钊 5宋金民 6王瀚 6陈明思 1杨钹 5唐攀 5陈荣庆 1丁一3
作者信息
- 1. 成都理工大学沉积地质研究院,四川成都 610059
- 2. 中国石油西南油气田公司勘探开发研究院,四川成都 610041
- 3. 成都理工大学沉积地质研究院,四川成都 610059;油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都 610059
- 4. 油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都 610059;西华大学,四川成都 610039
- 5. 中国科学院地质与地球物理研究所,北京 100029
- 6. 油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都 610059
- 折叠
摘要
绵阳-长宁拉张槽的形成机制及时间尚存在巨大争议,严重制约了灯影组油气勘探的部署.为更好地对拉张槽深水地层提供时代约束,深化拉张槽构造-沉积演化认识,基于露头描述、薄片观察、碳同位素测试,对广元地区 4 个露头剖面开展综合地层对比和沉积环境分析.岩石学及碳同位素特征表明,研究区实测 4 条野外露头剖面从下到上可划分为 4 个岩性段(Ⅰ～Ⅳ):岩性段Ⅰ为薄层泥质灰岩夹泥质白云岩条带,对应陡山沱组三段Shuram-Wonoka负偏段地层;岩性段Ⅱ以黑色页岩为代表,可对比陡山沱组四段;岩性段Ⅲ为块状白云岩-硅质岩序列,属于灯影组同期地层;岩性段Ⅳ以薄板状硅质岩为特征,相当于麦地坪组.其中,灯影组二段早期—麦地坪期,研究区从块状白云岩逐步过渡为薄板状硅质岩,见垮塌体及滑塌揉皱,指示台地转换为斜坡-盆地沉积环境.这种加深的沉积趋势与中上扬子台地相区变浅至暴露的过程完全相反,指示断裂活动影响下快速沉降的过程.
Abstract
The formation mechanism and time of the Mianyang-Changniang sag are still controversial,which significantly limit the petroleum exploration of the Dengying Formation.In order to provide a better time constraint on the deep-water strata in the Mianyang-Changning intracratonic sag and deepen the understanding of its tectonic-sedimentary evolution process,this study carries out comprehensive stratigraphic correlation and sedimentary environment analysis of four sections in Guangyuan area,based on outcrop description,thin section observation and carbon isotope analysis.The characteristics of petrology and carbon isotopes show that the four outcrop profiles in the study area can be divided into four lithologic units from bottom to top(namelyⅠ,Ⅱ,Ⅲ and Ⅳ).Lithologic unitⅠis composed of thin-bedded argillaceous limestone intercalated with argillaceous dolomite band,which is equivalent to the 3rd Member of the Doushantuo Formation with the Shuram-Wonoka negative δ13C excursion.Lithologic unit Ⅱis represented by black shale,corresponding to the 4rd Member of the Doushantuo Formation.Lithologic unit Ⅲ showing the transition from massive dolomite to chert,can be correlated with the Dengying Formation.Lithologic unit Ⅳ is marked by platy chert,which is equivalent to the Maidiping Formation.Of these,during the early stage of the second member of Dengying to Maidiping period,massive dolomite shifted to thin-bedded chert with slump breccias and fold deposited in the study area,indicating rapid evolution from carbonate platform to slope-basin depositional environment.This deepening depositional trend is opposite to the shallowing to exposure of the whole Middle-Upper Yangtze platform,indicative of rapid subsidence induced by extensional faulting.
关键词
绵阳-长宁拉张槽/广元地区/灯影组/地层对比/构造-沉积演化Key words
Mianyang-Changning intracratonic sag/Guangyuan area/Dengying Formation/stratigraphic correlation/tectonic-sedimentary evolution引用本文复制引用
基金项目
国家自然科学基金(41902105)
&&(U19B6003)
出版年
2024
国家科技期刊平台
NSTL
万方数据