Abstract:

Four types of dolomitized rocks have been found in the eastern sector of North Tarim uplift: 1. bedding stromatolite dolostone; 2. ribboned dolomitic limestone;3. remaining intraclastic breccioid calciferous dolomite-dolomite and 4. lumpy dolomitic limestone-calcic dolostone. The dolomites forming the above mentioned rocks are mainly a. subhedral-allotriomorphic granular dolomite; b. euhedral rhombohedron fine crystalline dolomite; c. euhedral rhombohedron fine silt-sized crystalline dolomite. The features of their mineralogy, cathodoluminescence and geochemistry show that the dolomitization in the area are all resulted from the mixing of fresh water and sea water. In consideration of the basic features of the sediments and texture, two periods of dolomitization and consequently two models of dolomitization are proposed in this paper: 1. shallow-buried fresh water dilution in near surface and 2. deep-buried fresh watre-pore bittern mixing.