Anarak metamorphites(central Iran

Category Paleontology and Stratigraphy
Group GSI.IR
Location 20th symposium on geosciences
Holding Date 16 April 2008

     Structural and stratigraphic studies were carried out in an area of
2500 km 2 around Anarak
town (Central Iran), and during the research a structural map with
100.000 scale was prepared.
straligraphy of metamorphic rocks (Anarak Mctamorphites) was studied in detail. Five
straligraphical sections with a total length of 12, 350 ni were measured and related
Stratigraphical columns were prepared, the results of the study requires some changes in previous stratigraphical cloumn of the area.
Moham madahad and Doshakh complexes are proposed to be removed from the stratigraphical lexicon. After clear understranding of the real stratigraphical position of the Chah Gorheh unit and its considerable thickness it is suggested to rename it as Chab Gorheh unit. Meanwhile distincitve Stratigraphical position of Pateyar Complex, Morghab Complex and Lak Marbnlc suggests to regard them as stratigraphical units.
On the basis of stratigraphical studies, Chah Gorbeh unit can he regarded as a combination of five members that from the base to the top include:
1. Sebarz Shist Member (Neoproterozoic),
2. Lower Marbles Member (Neoproterozoic).
3. Lower Schist Member (Neoproterozoic).
4. Middle Marbles Member (Manykayan).
5. Upper Shist Member (Tommotian).
Paleontological features and stratigraphical similarities are used to suggest assigning Lak marble Unit to the Atdabanian, Pateyar Unit to the Botomian and Morghab Unit to the Toyonian. Anarak Metamorphites show green schist and blue schist metamorphic facies. Their protoliths mainly seem to be pelitic — psamitic sedimentary rocks of torbiditic facies. Marbles with limestone and dolomite protoliths of varable thicknesses are
interbeddedwith the schists. -
It spite of previous interpretations, Anrak ophiolires dismembered in NeoProterozoic (PanAfrican) and are assigned to a back arc basin environment.