白云岩的残余结构及由此引发的孔隙分类问题

对碳酸盐岩的结构分类方法进行了评述,但目前的分类并未对白云岩的残余结构问题进行充分论述.为了能更准确地恢复岩相古地理和进行精细的成岩研究,有必要对残余结构进行细分.白云岩的残余结构是由于原始粒屑结构的灰岩,经白云岩化、重结晶、溶蚀、胶结等成岩作用之后,岩石原始结构遭到不同程度的破坏,但仍残留有部分原始结构信息而形成的....

Relict Textures of Dolomite and the Related Porosity Classification

The popular theory on texture classification of carbonates has not shed much light on the relict texture of dolomites, which is defined here as the texture remained of original limestone with >10% of grains after complete dolomitization and associated recrystallization, dissolution, fillings, and so on. It is emphasized for its important role in reconstructing the paleo environment of sedimentation. Based on whether most of the grains can be clearly and quantitatively distinguished with matrix and cements, and the inner texture of grains is preserved or not under microscope, the relict textures can be classified as the mimetic texture, the nonmimetic texture, and the ghost texture. These textures are described in detail with typical examples. The porosity classification of these relict textures should coincidently be refined after Choquette and Pray (1970). The pores are firstly classified as selective, partly selective or non selective. Intragranular, intergranular, and intercrystal pores are selectively developed within individual grains, between grains, or between individual dolomite crystals, respectively. Furthermore, if the intercrystal pores are selectively developed within individual grains, then they are classified into intragranular and called intragranular intercrystal pores. Similarly there are intergranular intercrystal pores. Notably, moldic porosity hereby is also intragranular because they are always within individual grains. Partly selective pores in this case refer to dissolution enlarged intragranular, intergranular, or intercrystal pores. And the common non selective pores are vugs, channels, caverns, fractures and breccia pores, as defined by Choquette and Pray (1970).