四川射洪县明星镇上侏罗统蓬莱镇组岩相及古气候意义

Sedimentary Facies and Its Paleoclimate Significance for the Upper Jurassic Penglaizhen Formation in Mingzhu Town,Shehong,Sichuan

对四川省射洪县"硅化木国家地质公园"博物馆剖面的上侏罗系蓬莱镇组进行岩相分析、观察研究表明,蓬莱镇组以紫色、紫灰色、灰绿色泥岩、细粒长石(石英)砂岩为主,含粉砂岩,可以识别划分出湖泊、河流和铁质氧化土壤三种岩相类型。其中,湖泊相可分辨出深湖、滨～浅湖亚相,河流相,并可进一步识别为河道、天然堤、决口扇、洪泛平原(/河漫滩)四种亚相。根据这些岩相和亚相的气候指示,结合下伏硅化木层位的岩相特征,认为研究区在蓬莱镇组沉积期属于半干旱气候。

Study of sedimentary facies indicates that the Penglaizhen Formation in the National Woodstone Geopark,Shehong is composed of purple,purplish gray,grayish green mudstone,fine-grained arkose and siltstone which may be divided into lacustrine,fluvial facies and iron oxide soil.The lacustrine facies may be subdivided into deep lake,coastal and shallow lake subfacies and fluvial facies may be subdivided into channel,levee,crevasse-splay,floodplain subfacies.The sedimentary facies indicates a semiarid climate.