Author(s)

A. Rahimi^1*, M. H. Adabi², A. Aghanabati¹, M. R. Majidifard³, A. M. Jamali⁴

¹Department of Geology, Faculty of Sciences, Islamic Azad University, North Tehran Branch, Tehran, Iran.
²Department of Geology, Faculty of Geology, Shahid Beheshti University, Tehran, Iran.
³Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran.
⁴Surface Geology Exploration Section Directorate, National Iranian Oil Company, Tehran, Iran.

Middle Triassic carbonate sequences of Shotori Formation have a thickness of 70 m and are deposited Robat-e-Kalmard region of Tabas city in Central Iran basin. Gradationally and conformably overlying Sorkh shale Formation, Shotori Formation, mostly composed of medium to thick dolomites (50 m), interbeded with thin lime and sandstones, is disconformable by a laterite horizon at its upper boundary. This Formation mainly consists of fine-to-coarsely crystalline dolomites. According to petrographic (fabric and grain size) and geochemical (elemental analysis of Ca, Mg, Na, Sr, Fe, Mn) evidence, five various types of dolomites were recognized in Shotori Formation. This variety results from early and late diagenetic processes, triggering a change in dolomitizing fluids and thereby forming various dolomites. Geochemical studies have revealed that the dolomites of Shotori Formation have formed under meteoric diagenesis and reducing conditions. Various dolomitization mechanisms are proposed for various types of dolomites; that is to say, Sabkha model is considered for type 1 dolomite, mixing zone model for type 2 and 3 dolomites and burial model for type 4 and 5 dolomites.

Dolomitization, Petrography, Geochemistry, Shotori Formation, Central Iran

Rahimi, A. , Adabi, M. , Aghanabati, A. , Majidifard, M. and Jamali, A. (2016) Dolomitization Mechanism Based on Petrography and Geochemistry in the Shotori Formation (Middle Triassic), Central Iran. Open Journal of Geology, 6, 1149-1168. doi: 10.4236/ojg.2016.69085.