On the micrite envelope to restoration of primary texture character of secondary dolomites and its significance.

The remainder texture of the secondary dolomites and the processes and sign ificances of the Micrite Envelope (ME) that could protect the texture and o utline of the gains not subjecting deformation by diagenesis are systematic ally studied in this paper, based on the data of the thin section, SEM, cat hodluminescence thin section etc., and combined with the theories of the mi neralogy, petrology, sedimentology and chemistry. According to the texture components of carbonate rocks, the intension of replacement and the identif iability of the texture and the ME, the remainder textures can be classifie d into 3 types: replacement remainder texture, replacement image texture an d replacement crystalline grain texture; and every type of remainder textur e can also be divided and named by variety components. It is very important that finding and identifying the remainder texture and the image or outlin e of the grain in the research process, thus the primary texture and the gr ain type can be reconstructed, and the primary rock type too. Based on the studies above and combined with theory analysis, it is pointed out that the micrite envelopes not only are not damaged thoroughly, but also play a pro tection role to the outline of the grains, and increase the velocity in the earlier processes of dolomitization, because the envelops are mainly const ituted by aragonites, microcrystalline calcites, organic matters and some o f clays that have effects of molecular sieve and permeable membrane, especi ally to those limestone bearing some of grains. Therefore, the author consi dered that the investigations of the remainder textures, especially the ME, are very important to restoration of the sedimentary environment, the pala eoclimate, ancient oceanography, stratigraphy, tectonics and the carbonate primary type basin.