皖北二叠系主要含煤段三角洲平原类型及其沉积构成

TYPES OF NORTH ANHUI DELTA PLAINS WITH PERMIAN COAL MEASURES AND THEIR SEDIMENTARY ARCHITECTURE

研究表明，皖北山西组至上石盒子组第１，２段地层单元沉积主体为河控三角洲体系．综合内部构成、砂分散格式和砂体宽厚比特征，将广布的分流水边充填进一步划分为４种类型，据相构型，尤其是砂分散格式及骨架相类型组合，划分出进积型和水道充填型三角洲平原。前者包括前缘进积和湾决口进积三角洲平原，后者包括树枝状、网状和弯曲状分流三角洲平原。阐明了这些不同类型三角洲平原的主要沉积特征及其演化关系。

Based on our investigation in this area,the main sedimentation from Shanxi Formation to the first two members of Upper Shihezi Formation is chiefly a fluvial dominated delta system. Taking into consideration of its internal structure,distribution patterns and features of the sand body(width and thickness) the widely distributed channel fill can be further divided into four types. Again progradational and channel fill delta plains are found based on the facies structure ,especially dispersion patterns of the sand body and combination modes of framework facies. The former includes front progradational delta plain and bay crevasse progradational delta plain ;the latter includes delta plains with branched, anastomotic and sinuous distributaries. The paper describes the major sedimentary characteristics of different types of delta plain and its evolution.