开江-梁平陆棚东南延伸部分——建南陆棚的发现

The discovery of the Jiannan shelf in the southeastern part of the KaijiangLiangping shelf

关键词:  长兴期  建南浅水陆棚  开江-梁平陆棚  生物礁  沉积模式

Key words:  Changxingian  Jiannan shallow-water shelf  Kaijiang-Liangping shelf  bioherm  sedimentary model

摘要:

自王一刚发现开江-梁平陆棚后,作者对其东南延伸部位进行了追踪。通过地表露头剖面及钻井、地震资料等研究后认为,长兴期开江-梁平陆棚自宣汉达县、梁平及开江地区向东南延伸至建南地区,称之为建南陆棚,该陆棚可能与东部的鄂西陆棚相连。建南陆棚与开江-梁平陆棚既有相似性也有重大差别。相似性表现在两方面,一是沉积物岩性相似,都为泥晶灰岩;二是陆棚边缘都发育生物礁,生物礁顶部发育生屑滩白云岩储层。差别主要体现在四个方面:一是水体深度,建南陆棚水浅,开江-梁平陆棚水深,深水与浅水的交汇处在涪陵地区中石化二维地震剖面线TB16与TB17之间;二是斜坡坡度,开江-梁平陆棚边缘斜坡坡度陡,建南陆棚斜坡坡度缓;三是生物礁规模,开江-梁平陆棚边缘生物礁、白云岩储层厚度大,建南陆棚边缘生物礁、白云岩储层厚度小;四是陆棚发育时间,建南陆棚仅发育于长兴早中期,晚期因填平补齐而消失,开江-梁平陆棚发育于整个长兴期。建南陆棚与周边构成碳酸盐缓坡沉积模式,生物礁规模较小,生物礁是优质储发育的主要地区。

Abstract:

On the basis of outcrops, cores and seismic data in this study and the previous data, the author in this study proposes a new shelf, i. e., the Jiannan shelf that represents the southeastward extended part of the Kaijiang-Liangping shelf penetrated from the Xuanhan-Daxian-Liangping-Kaijiang zone southeastwards to the Jiannan area during the Changxingian, and may be connected with West Hubei shelf in the east. Compared with the Kaijiang-Liangping shelf, the Jiannan shelf has the following features. (1) The Jiannan shelf is a shallow-water shelf. (2) The Jiannan shelf was initiated during the early-middle Changxingian and terminated due to the filling up during the late stages of the Changxingian. (3) The Jiannan shelf and its adjacent areas exhibit a carbonate ramp model in which the Changxingian bioherms occur as excellent dolostone reservoirs with good physical properties.