塔中地区寒武-奥陶系白云岩成因类型及空间分布

Genesis types and distribution pattern of the Cambrian and Ordovician dolomites in Tazhong area,the Tarim Basin

寒武-奥陶系白云岩是塔里木盆地下古生界碳酸盐岩中重要储集岩类,综合岩心、镜下、结构组分及宏观地质背景等各种特征,将塔中地区寒武-奥陶系白云岩划分为五种类型,重点对Ⅱ型细晶及Ⅲ型中粗晶白云岩显微结构特征进行了详细阐述,指出Ⅱ型细晶白云岩具三种产状两种结构特点。Ⅲ型白云岩可以以充填物形式产于大型缝洞内,具镶嵌状结构,可同时包含Ⅰ型和Ⅱ型白云岩。探讨了白云岩的沉积组合及空间分布规律,指出了蒸发海水型、混合水型、岩溶型、埋藏型、深部溶蚀型及同生砾屑云岩等各类型白云岩储层的有利发育区带。

The Cambrian and Ordovician dolomites are important reservoir rocks of Lower Paleozoic carbonate in Tarim Basin,which can be divided into five genesis types according to various characteristics such as cores,microscopic features, textural components and macro-geology. In this paper, the mierotextures of Type Ⅱ fine crys- talline dolomite and Type m medium-coarse crystalline dolomite are described in detail,with the fine crystalline dolomite characterized by three attitudes and two textures. The Type Ⅲ dolomite can occur in bigger caves and fractures as a fill, which has a mosaic texture and may contain both Type I and Type Ⅱ dolomites. The sedi- mentary combination and distribution pattern of the dolomites are discussed, and the favorable development zones of various types of dolomite, such as evaporated-seawater type, mixed-water type, karstification type,burial type, deep-dissolution type and syngenetic rudaeeous type,are pointed out.