-

The Elika Formation (Lower Triassic) comprises a platform carbonate sequence which extend over 10000 sq. Km in the Alborz Mountains and consists of rather persist ant dolomite units.
Petrography examination of dolomite rocks of the lower part of the Elika Formation reveals that they consist of at least 7 different types of dolomite as follows:
1) Finely crystalline, generally planar, euhedral-subhedral dolomite with primary depositional textures.
2) Medium crystalline dolomite in which rhombs are euhedral, planar, and cloudy core-clear rim.
3) Medium crystalline zoned sucrosic dolomite with euhedral and planar rhombs.
4) Dolosparite cement, in which dolomite occurs either as cavity I fracture leaning or cavity I fracture filling.
5) Finely crystalline subhedral dolomite which is associated with pressure solution.
6) Medium to coarse crystalline xenotopic dolomite with anhedral and no planar crystals.
7) Saddle dolomite which is characterized by tabular shape, curved surface, and sweeping extinction.
Three phases of dolomitization are recognized in the lower part of the Elika Formation: an early sabkha dolomite (type 1); dolomites related to mixed fresh-water and salt-water of Dorag model dolomitization (types 2,3 and 4); and dolomites formed during burial (types 5,6, and 7).