层序地层与同位素地球化学响应特征及礁滩发育模式——以川东城口—鄂西海槽边缘带长兴组为例

Sequence stratigraphy and isotope geochemical response and development pattern of reef and shoal: a case study of Changxing Formation in the marginal zone of Eastern Sichuan Chengkou-Western Hubei Oceanic Trough

董庆民 胡忠贵 蔡家兰 李世临 苏楠 左洺滔 秦鹏

DONG Qingmin HU Zhonggui CAI Jialan LI Shilin SU Nan ZUO Mingtao QIN Peng

1. 长江大学 沉积盆地研究中心, 武汉 430100; 2. 中国石油 西南油气田公司 重庆气矿, 重庆 400021; 3. 中国石油勘探开发研究院, 北京 100083

1. Sedimentary Basin Research Center, Yangtze University, Wuhan, Hubei 430100, China; 2. Chongqing Gas District, Southwest Oil and Gas Field Co., Ltd., PetroChina, Chongqing 400021, China; 3. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China

川东地区上二叠统长兴组生物礁滩相带具有巨大的油气勘探潜力，分析层序地层与同位素组成的响应特征及礁滩发育模式，可为该区礁滩勘探提供可靠的地质依据。通过对城口-鄂西海槽边缘带典型露头剖面观察及层序地层分析，结合长兴组碳同位素组成特征，对长兴组层序地层与同位素地球化学响应特征及同一区域内礁滩发育模式进行了研究，将长兴组划分为2个三级层序，5个四级层序，层序格架内碳同位素与海平面升降变化具有良好响应关系。不同沉积相带其礁滩发育模式具有明显差异，迎风一侧的盘龙洞剖面处于最高能台缘相带，礁滩最为发育，云化作用明显，储层发育；背风一侧、同属于台缘带的羊鼓洞剖面，礁滩发育次之，云化作用较弱；而处于开阔台地的渡口剖面，只发育台内颗粒滩沉积，储层不发育。

The Upper Permian Changxing Formation reef and shoal in the eastern Sichuan Basin has great potential for oil and gas exploration. The analysis of sequence stratigraphic and isotopic composition response as well as reef and shoal development patterns can provide a reliable geologic basis for reef and shoal exploration in this area. Observation of the typical outcrop section and the sequence stratigraphic analysis of the margin of the Chengkou-Western Hubei Oceanic Trough, combined with the carbon isotope composition of the Changxing Formation, show the sequence stratigraphic and geochemical response characteristics of the Changxing Formation and the reef and shoal development patterns. The Changxing Formation was divided into two third-order sequences and five fourth-order sequences. The carbon isotope distributions in the sequence framework have a good relationship with sea level fluctuation. There are obvious differences in the development patterns of reef and shoal in different sedimentary facies belts. The Panlongdong section on the windward side is in the highest energy platform margin belt, where reef and shoal are the most developed, the dolomitization of reef and shoal is obvious, and the reservoir is developed. In the Yanggudong section, which is on the leeward side of the platform margin, the development of reef and shoal takes the second place, and the dolomitization is weak. However, only the intra-platform grain shoal is developed in the Dukou section in the open platform, and reservoir is not developed.

十三五国家科技重大专项"重点海相层系构造-沉积响应与有利储层分布预测"（2016ZX05007002）和长江青年人才基金项目（2015cqr09）资助。

https://doi.org/10.11781/sysydz201902243