Abstract: According to the lithology and geochemistry analyses, the Permian and Triassic dolostones in Northeastern Sichuan Province can be classified into three types: reef dolostone, grain dolostone and gypsum-bearing muddy dolomicrite The reef dolostone is formed in mixed water which is mainly controlled by frequent change of the sea level Grain dolostone is formed in the deep burial dolomitic environment by mixing-water dolomitization Penecontemporaneous or seepage-reflux dolomitization is the original mechanism for gypsum-bearing muddy dolomicrite

Key words: Northeastern Sichuan Province, dolostones, dolomitization, original mechanism

摘要： 通过对川东北二叠系-三叠系白云岩岩石学和地球化学特征分析，表明研究区内白云岩按沉积相及相应的岩石结构特征主要分为3类：礁白云岩、颗粒白云岩和泥晶-微晶白云岩（含膏云岩）。礁白云岩具有典型的混合带白云石化特点，受海平面频繁变化影响；颗粒白云岩的形成与混合水白云石化作用和深埋藏成岩作用有关；准同生白云石化或卤水回流渗透白云石化是泥晶-微晶白云岩（含膏云岩）的形成机制。

关键词: 川东北, 白云岩, 白云石化, 成因机制