川南地区上三叠统须家河组沉积特征与沉积演化模式

Sedimentary Characteristics and Evolution Model of the Upper Triassic Xujiahe Formation in the Southern Sichuan

通过岩心及薄片观察,从岩石学、沉积构造、古生物标志及测井曲线特征等方面,对川南地区须家河组沉积特征及沉积演化模式进行了深入分析。结果表明:研究区在须家河组为三角洲、湖泊及有障壁海岸等多种沉积类型均有发育的复合体;并受印支运动的控制发生变迁;其中三角洲沉积体系皆为辫状河三角洲沉积体系,根据进入蓄水盆地性质的不同可划分为湖泊三角洲和海相三角洲,湖泊沉积体系滨湖和浅湖亚相发育;有障壁海岸沉积体系潮坪较发育。在此基础上,结合构造特征分析了该区须家河组在不同时期的沉积特征及控制因素,认为须一段到须六段总体上为一连续沉积过程;并建立了海相-海陆过渡相-陆相三种连续的沉积相演化模式。

Based on the core and thin section observation,the sedimentary system of Xujiahe Formation in the Southern Sichuan from the aspects of petrology,sedimentary structures,paleontology evidence and well logging. on the basis of regional formation,sedimentary characteristics and sedimentary evolution model of group carried on the thorough analysis. It is believed that the sedimentary system include delta,lake and barrier coast. Among them,delta sedimentary system can be divided into braided fiver delta,in accordance with the different properties of water run off into the water basin,Results show that the area should be as a center of delta,lake and barrier coast multitypes sedimentary system is complex. Lake sedimentary system consists of two sub-facies,including lakeshore and shallow lake. Barrier coast sedimentary system mainly consists of tidal flat sub—facies. The delta sedimentary system of braided river delta sedimentary system,in the light of the different nature of entering water storage basin can be divided into lake delta and marine delta,lake lakeside and shallow lake sedimentary system development two subfacies deposition; Barrier coast tidal flat sedimentary system development and deposition. On this basis,respectively established the marine,terrestrial transitional facies and continental three types of sedimentary facies model. Episodic structural movement characteristics of the area,Xujiahe formation in different periods of sedimentary facies distribution characteristics and the control factors.