L. Izadi kian; A. Alavi; M. Mohajjel
Abstract
The Simin- Darreh Moradbeik shear zone is located in the south of Hamedan city with 5 km width and at least 10 km length. The portion of contact metamorphic rocks, plutonic rocks and migmatits are affected by this shear zone. At least three ductile deformation stages are recognized by folding and foliation ...
Read More
The Simin- Darreh Moradbeik shear zone is located in the south of Hamedan city with 5 km width and at least 10 km length. The portion of contact metamorphic rocks, plutonic rocks and migmatits are affected by this shear zone. At least three ductile deformation stages are recognized by folding and foliation of each stages of deformation. All of deformation stages are coaxial and created interference pattern of folding. Field evidence shows tension and shear stress in this area. The shear zone dips to northeast and northwest with normal sense of shear movement. This shear zone deformed locusom of migmatite, boudinage of andalusite porphyroblast and formed granitic mylonite from Khako granite. Distribution of mylonitic foliation poles show refolding of this shear zone at the next deformation stages. According to deformation stages in Hamadan tectonites, possibly this shear zone formed syn to post second deformation (D2)
M. Mohajjel; L. Izadi kian
Abstract
Almabolagh region is located in northwestern part of the Sanandaj-Sirjan zone of Zagros orogen in western Iran. This area is located 15 km to the west of Hamadan. Three rock units consisting of volcani-sediments (Almabolagh sequence) at the lower part, carbonate (Chenarsheikh ...
Read More
Almabolagh region is located in northwestern part of the Sanandaj-Sirjan zone of Zagros orogen in western Iran. This area is located 15 km to the west of Hamadan. Three rock units consisting of volcani-sediments (Almabolagh sequence) at the lower part, carbonate (Chenarsheikh sequence) in the middle, and slate (Hamadan slate) at the upper part are identified. These rocks that are metamorphosed at green schist facies have been exposed in a dome structure. Four stages of deformation (D1, ..., D4) are identified in the tectonites. D1 structures include first generation folds and related axial planar schistosity. D2 structures are recognized by tight to isoclinal, recumbent shallowly plunging folds, with horizontal to sub-horizontal axial plane schistosity which is the predominant foliation in this area. The mechanism of folding in this stage is flexural shearing and passive flow. D3 structures are identified by the third generation foliation that is weakly developed parallel to the axial surface of related upright, open to gentle folds. The third generation folds were produced by flexural slip mechanism. A dome structure generated by intrusion of magmatic batholith in this region and structural elements of the main deformation stages (D2) were rotated.
