摘要
本文在野外剖面调查的基础上,结合薄片观察,对川东南地区三汇剖面寒武系洗象池组237块碳酸盐岩样品进行了系统的碳氧同位素组成研究,结果表明,δ^(18)O值主要分布在-8‰～-6‰,平均为-7.63‰;δ^(13)C值介于-5.53‰～3.44‰之间。利用碳氧同位素数值计算古盐度及古温度结果表明,绝大多数Z值高于120‰,且δ^(13)C值大于-2‰,古海水温度主要集中在19～25℃,说明整体为海水-咸化海水沉积环境与温暖或炎热的亚热带气候。认为洗象池组沉积期海平面变化有五个阶段:早期缓慢上升与下降,中期快速海侵,中后期缓慢海退,后期动荡,末期海退。三汇剖面洗象池组储集层岩性主要为颗粒云岩及晶粒云岩,储集空间以溶蚀孔洞、粒间孔与晶间孔为主。多期的海平面的下降,对应碳同位素多旋回负漂,从而发育向上变浅的多旋回韵律性地层,形成纵向上的多套储集层,洗象池组储集层的形成与演化受海平面变化控制,主要发育在古地貌较高处与滩体向上变浅旋回的上部。另外,依据δ^(13)C值显著的正漂移,明确了芙蓉统地层的底界,为四川盆地寒武系地层的划分提供了证据。
Based on the Sanhui outcrop survey and thin section observation,carbon and oxygen isotopic compositions of 237 Xixiangchi Formation samples are studied in Southeastern Sichuan Basin.The results show that values ofδ18O are relatively stable,mainly from-8‰to-6‰,with an average of-7.63‰.The variation range ofδ13C values is-5.53‰-3.44‰.Using the carbon and oxygen isotope to calculate the paleotemperature and paleosalinity,the result show that the Z value is higher than 120‰,the paleotemperature is about at 19℃to 25℃,and it told us that the sedimentary period is generally in seawater-saline seawater environment,which was a warm or hot subtropical climate.It was considered that there are five sea level change stages during sedimentary period:slowly transgression and regression in early,rapid transgression in middle,slow regression in late-middle time,fluctuation in late,regression in the end.The reservoir rock for Xixiangchi formation in Sanhui section are mainly dolomite?the revisor space is composed of dissolution pores intergranular pores and intergranular pores.The decline of multistage sea level corresponds to the negative drift of carbon isotope,thus developed a multi cycle prosodic stratigraphic formation that is upward and shallow,forming multiple sets of reservoirs in the vertical.The formation and evolution of the reservoir for the Xixiangchi Formation was controlled by the change of sea level,mainly in the upper paleogomorphology and the upper part of the shallow cycle.In addition,based on the significant positive of value,the bottom boundary of the Furong formation is clearly defined,which provides evidence for the division of Cambrian strata in the Sichuan basin.
作者
李文正
张建勇
郝毅
倪超
田瀚
曾乙洋
姚倩颖
山述娇
曹脊翔
邹倩
LI Wenzheng;ZHANG Jianyong;HAO Yi;NI Chao;TIAN Han;ZENG Yiyang;YAO Qianying;SHAN Shujiao;CAO Jixiang;ZOU Qian(PetroChina Hangzhou Research Institute of Geology,Hangzhou,310023;CN PC Key Laboratory of Carbonate Reservoirs,Hangzhou,310023;PetroChina Southwest Oil &? Gas Field Company,Chengdu,610051;Chuan zhong Oil and Gas Field of Petrochina Southwest Oil & Gas Field Company,Suining,Sichuan,629000;PetroChina Research Institute of Petroleum Exploration & Development,Beijing,100083)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2019年第2期487-500,共14页
Acta Geologica Sinica
基金
"十三五"国家专项(编号2017ZX05008-005,2016ZX05004-002)
中国石油天然气股份有限公司重大科技项目(编号2018A-0105)资助的成果
关键词
洗象池组
寒武系
碳氧同位素
古环境
储集层
Xixiangchi Formation
Cambrian
carbon and oxygen isotopes
paleoenvironment
reservoir
