四川盆地宣汉—开江古隆起的发现及意义  

Discovery of Xuanhan-Kaijiang Paleouplift and its significance in the Sichuan Basin, SW China

作　　者：谷志东[1] 殷积峰[1] 姜华[1] 李秋芬[1] 翟秀芬[1] 黄平辉[2] 彭平[2] 杨帆[1] 张航[2] 

机构地区：[1]中国石油勘探开发研究院 [2]中国石油西南油气田公司

出　　处：《石油勘探与开发》2016年第6期893-904,共12页Petroleum Exploration and Development

基　　金：国家油气科技重大专项"四川盆地下古生界-震旦系成藏条件研究与区带目标评价"(2016ZX05004-005);中国石油天然气股份公司科技项目"四川盆地震旦-寒武系接替领域研究与风险目标优选"(101015kt1004001b22)

摘　　要：通过多种地质资料研究,基于四川盆地东部地区3方面依据,提出该区发育前震旦纪—早寒武世宣汉—开江大型继承性古隆起:1地震显示震旦系灯影组、下寒武统由周缘向宣汉—开江地区超覆沉积;2灯影组厚度显示宣汉—开江地区最薄,向周围增厚;3城口、巫溪等露头灯影组发育碎屑岩间接指示古隆起的发育。通过对古隆起的发育特征、形成演化分析,发现古隆起平面近穹窿状、南北向延伸,面积约1.6′104 km2;纵向划分为核部平台区、西侧陡坡带与东侧缓坡带3部分;晚震旦世早期为水上剥蚀型古隆起,晚震旦世晚期—早寒武世转为水下沉积型古隆起,形成受基底隆升、克拉通内裂陷、基底断裂与区域抬升运动联合控制。古隆起及斜坡区有利于高能沉积相带与岩溶风化壳储集层的发育,是川东地区近期重要战略接替勘探领域。A large inherited paleouplift from pre-Sinian to Early Cambrian, named Xuanhan-Kaijiang paleouplift, has been discovered based on multiple geological information in the eastern Sichuan Basin： firstly, onlap deposition of Upper Sinian Dengying Formation and Lower Cambrian is observed from peripheral zone to central Xuanhan-Kaijiang area from the seismic profile; secondly, Dengying Formation thickness distribution map shows that this formation is thinnest in Xuanhan-Kaijiang area, and thickens towards the surrounding areas; thirdly, terrigenous clastic rock is observed in Upper Sinian Dengying Formation on outcrops in Chengkou County and Wuxi County etc., indicating the development of a paleouplift. The analysis of the characteristics, formation and evolution of the paleouplift reveals that the plane distribution of the paleouplift shows an arched structure, stretching in a north-south trend. The area of the paleouplift is around 16 000 km^2. Vertically, the paleouplift can be divided into three parts： platform in the middle, steep slope in the west and ramp in the east. Originally, the paleouplift was an erosion-type uplift above the water level during the early stage of the Late Sinian; and gradually transformed into deposition-type uplift under water level during the late stage of the Late Sinian to the Early Cambrian. The formation of the paleouplift was controlled by several factors, including basement uplift, intracratonic rift, basement faults and regional uplifting. The paleouplift and its slope areas, favorable for the development of high energy facies and karst weathering reservoirs, are important exploration target areas in the eastern Sichuan basin in the near future.

关 键 词：四川盆地 川东地区 古隆起 宣汉—开江古隆起 震旦纪—早寒武世 克拉通内裂陷 超覆沉积 

分 类 号：TE122.2[石油与天然气工程—油气勘探]