The Upper Jurassic (Kimmiridgian-Tithonian) Mozduran Formation in the Kopet-Dagh basin is mainly composed of limestone and dolomite with minor amounts of silisiclastic and evaporaite sediments. The purpose of this study is to identify and differentiate dolomite types in this formation, north of Chenaran. Based on petrographic studies, two types of dolomitization (fabric selective and pervasive) have occurred. More detail studies of the pervasive dolomite led to recognition of three different dolomite types including: fine to medium crystal, coarse crystal and cement. Elemental and stable isotope analysis indicated that the Mozduran dolomites were subjected to a complex diagenetic history. The calculated temperature for dolomitization of D_P1, D_P2 and D_P3 dolomites are 58°^C, 64°^C and 80°^C respectively.