四川盆地晚二叠世岩相古地理特征及演化

Lithofacies Paleogeographic Characteristics and Evolution of Late Permianin in Sichuan Basin

采用单因素分析多因素综合作图法对四川盆地晚二叠世吴家坪期和长兴期岩相古地理进行研究和编图。吴家坪期岩相古地理单元包括剥蚀区、冲积平原、碎屑岩台地、碳酸盐岩台地、斜坡(过渡带)和盆地;长兴期岩相古地理单元包括冲积平原、碎屑岩台地、碳酸盐岩台地、斜坡和盆地。四川盆地晚二叠世总体为一个海侵的过程,海水自北东向南西方向入侵,各古地理单元依次向西退却,吴家坪期碎屑岩台地为主体的沉积环境演变为长兴期碳酸盐岩台地为主体,碳酸盐岩台地内部发育生物礁和生屑滩。

According to the single factor analysis and multifactor comprehensive mapping method,the lithofacies paleogeography of Wujiaping stage and Changxing stage of Late Permian in Sichuan Basin is studied and mapped,the paleogeographical units of Wujiaping stage include eroded area,alluvial plain,clastic platform,carbonate platform,carbonate slope(transitional zone)and basin,these also include in Changxing stage.In general,it is a transgressive process of late Permian in Sichuan Basin,resulting from transgression from the northeast to the southwest,the paleogeographical units recede westward successively,the clastic platform as the main body of Wujiaping stage evolves into carbonate platform of Changxing stage,and high-energy reefs and bioclasts shoals develop locally in the carbonate platform.The paleogeographical units have an obvious control on the development of source and reservoir rocks,the favorable oil-gas generating units include clastic platform,basin,carbonate slope(transitional zone)and carbonate platform.