鄂西地区大隆组沉积类型及地质时代

鄂西地区的大隆组富含菊石类化石 ,下部产 K onglingites、 Sanyangites、 Jinjiangoceras等 ,上部产 Pseu-dotirolites、 Tapashanites、 Changhsingoceras、 Pleuronodoceras等 ,时代为晚二叠世吴家坪晚期至长兴期。自西而东存在 3种沉积类型 ,即为硅质岩—灰、泥岩型、泥岩—硅质岩型和硅质灰岩—泥岩型。硅质岩层在区域上存在穿时性现象。大隆组与下伏吴家坪组的接触关系有两种 :连续沉积的整合接触和间断沉积的似整合接触

Sedimentation Types and Age of the Dalong Formation in Western Hubei

The Dalong Formation in western Hubei yields a large number of ammonoids, including Konglingites, Sanyangites, Jinjiangoceras , etc. in the lower part and Pseudotirolites, Tapashanites, Changhsingoceras, Sinoceltites, Pleuronodoceras , etc. in the upper part. These ammonoids suggest an age from late Wuchiapingian to Changhsingian. There are three sedimentation types for the Dalong Formation in this area from west to east, i.e., silicate-limestone and mudstone type, mudstone-silicate type and siliceous limestone-mudstone type. The silicate beds are diachronous. The Dalong Formation is underlain conformably by the Wujiaping Formation in the silicate-limestone and mudstone type area, and paraconformably in the others.