四川盆地东北地区中—下二叠统层序地层特征研究

STUDY ON THE MIDDLE-LOWER PERMIAN SEQUENCE STRATIGRAPHY IN NORTHEASTERN AREA, THE SICHUAN BASIN

李凤杰 陈荣林

Li Fengjie Chen Ronglin

成都理工大学, 沉积地质研究院, 成都, 610059 2. 中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, Sichuan 610059, China 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu, 214151, China

在野外地质剖面实测、岩性地层、沉积相和可容空间变化分析的基础上,运用层序地层学的原理,对川东北地区宣汉县渡口镇羊鼓洞中—下二叠统剖面的层序地层进行研究,识别出3种类型6个层序界面,将中—下二叠统划分为2个Ⅱ级、5个Ⅲ级层序地层,其中在梁山组、栖霞组和茅口组分别识别出1、2和2个Ⅲ级层序地层。在II级层序中,低位体系域主要发育滨岸沼泽相沉积,海侵体系域沉积相主要为局限台地或碳酸盐缓坡,高位体系域主要发育开阔台地沉积。同时,在层序划分的基础上建立了川东北地区中—下二叠统的层序地层格架。将可容空间变化曲线与露头层序地层划分之间进行对比,发现二者之间存在着良好的对应关系,这也佐证了层序地层划分的正确性。

On the basis of sequence stratigraphic theory and the analysis of sedimentary facies,lithology and lithofacies and change of accommodation of field profile,the Middle-Lower Permian sequences stratigraphy at Yanggudong profile in Dukou town,Xuanhan County,Northeastern of the Sichuan Basin were studied.Three types,six stratigraphic sequence boundaries were discriminated.One grade Ⅱ sequence and five grade Ⅲ sequences in Middle-Lower Permian,one grade Ⅲ sequence in Liangshan Formation,two grade Ⅲ sequences in Qixia Formation and two grade Ⅲ sequences in Maokou Formation were determined.In grade Ⅱ sequence,strand swamp facies was mainly developed in lowstand systems tract,restraint platform facies or carbonate gentle slope facies in transgressive systems tract and open platform facies mainly in highstand systems tract.At the same time sequence stratigraphic framework of the Middle-Lower Permian was built.By the comparison of the change of accommodation curve and outcrop stratigraphic sequence curve,there was a very well corresponding relation between the two curves,which implied the correct of classification of the sequence stratigraphy.

国家自然科学基金项目(40672073)

https://doi.org/10.11781/sysydz200805472