中、上扬子地区构造层序地层及原型盆地沉积环境演化

Tectonic sequence stratigraphy and sedimentary environment evolution of prototype basin in middle and upper Yangtze Region

为了促进我国南方页岩气勘探开发,应进行层序地层、沉积环境等地质理论研究,通过野外地质调查、钻井地质分析以及参阅前人资料,对四川盆地、渝东、湘鄂西地区综合地层对比,并进行构造层序地层划分,恢复中、上扬子地区重要地质历史时期原型盆地的沉积环境。研究结果表明:中、上扬子地区从震旦纪以来划分出3个构造层序:从震旦纪到志留纪为第1次,形成一个完整的威尔逊旋回;从泥盆纪到三叠纪为第2次,形成另1个完整的威尔逊旋回;从侏罗纪到新近纪为第3次,形成第3个完整的威尔逊旋回。3个构造层序反映了整个扬子板块的构造演化历史。构造层序的主要控制因素为板块间洋盆的扩张与闭合运动,每个构造层序不同阶段的沉积环境取决于沉积盆地距离主控洋盆的位置。

In order to promote the exploration and development of shale gas in southern of China,the geological theory of sequence stratigraphy,sedimentary environment and so on was carried out. Through field geological survey,drilling geology research and reference to previous geological data,comprehensive stratigraphy was compared in Sichuan Basin,eastern Chongqing and western Hunan-Hubei,and tectonic sequence stratigraphy was divided and the sedimentary environment of prototype basin of middle and upper Yangtze region was restored in important geological period.The results showed that three tectonic sequences had been divided in the middle and upper Yangtze Region since Sinian. It was the first structural sequence from Sinian to Silurian Period,which formed a complete Wilson Cycle. It was the second structural sequence from Devonian to Triassic,which formed a complete Wilson Cycle. It was the third structural sequence from Jurassic to Neogene,which formed a complete Wilson Cycle. The three tectonic sequences reflected the tectonic evolution history of entire Yangtze Plate. The main controlling factors of tectonic sequence was the expansion and closed movement of oceanic basin between plates and the sedimentary environment of each stage of tectonic sequence depended on the basin＇s distance from the master ocean.