塔东南坳陷侏罗系杨叶组沉积相特征及古环境研究

沉积环境影响着烃源岩的发育情况,因而研究侏罗系杨叶组沉积时的古环境对塔东南坳陷的勘探开发及有利区块的优选有着重要意义。本文根据区内已有钻井的岩心观察结果、岩电组合特征、分析化验资料和野外露头及古生物特征,对区内侏罗系杨叶组的沉积相特征及古环境进行了分析研究,指出了该区沉积相主要发育有辫状河三角洲沉积和湖泊沉积。其沉积环境为陆相淡水环境,具有较强的还原性;古气候为温暖半潮湿亚热带气候。提出该区优质烃源岩形成的最有利相带的浅湖-半深湖湖湾环境。通过对沉积相和古环境的研究,总结了沉积相平面展布特征和四大控制因素。

Sedimentary Facies Characteristics and Palaeoenvironment of Jurassic Yangye Formation in the Southeastern Depression of the Tarim Basin

Depositional environment is directly related to the development of source rock, and hence the study of the depositional environment has important significance for optimizing the favorable exploration blocks. The authors studied sedimentary facies characteristics and palaeoenvironment of Jurassic Yangye Formation on the basis of core observation, lithologic-electric logging features, test data, outcrop and palaeontological features. It is pointed out that the study area has developed two types of sedimentary facies: braided delta river facies and lake facies. The palaeoenvironment was a terrestrial freshwater environment characterized by strong reducibility. The paleoclimate was in a warm-humid climate background. A viewpoint confirmed by the field investigation is given, arguing that the optimum sedimentary facies were the shallow to half-deep lakes. Based on investigating the source rock sedimentary facies and palaeoenvironment, the authors have summarized the flat facies characteristics and the four main controlling factors.