扬子地台西缘宁蒗-盐源地区志留系牙形刺生物地层特征

The Silurian Conodont Biostratigraphical Characteristics of Ninlang-Yanyuan Region on the Western Margin of Yangtze Block

本文详细研究了宁蒗 盐源地区志留系岩石地层和牙形刺生物地层特征 ,自下而上建立了 3个牙形刺组合带 :①Panderodusgracilis Panderodussimplex组合带 ;②Pterospathoduscelloni组合带 ;③Pterospathodusamorphog nathoides组合带。从生物地层学、沉积学和区域对比的角度分析了Pterospathoduscelloni带和Pterospathodusamor phognathoides带之间的相互重叠关系 ,并认为其相互关系为渐变演化关系 ,不是突变关系。

This paper reports for the first time on the characteristics of Silurian stratigraphy and conodont biostratigraphy in Ninlang-Yanyuan region on the western margin of Yangtze block. The stratigraphical distribution of conodonts allows the establishment of three assemblage zones in ascending order:①Panderodus gracilis-Panderodus simplex;②Pterospathodus celloni;③Pterospathodus amorphognathoides. From the viewpoint of biostratigraphy, sedimentary and regional correlation, the authors, based on an analysis of the overlapping relationship between Pterospathodus celloni zone and Pterospathodus amorphognathoides zone, consider that the change from the former to the latter occurred gradually instead of abruptly.