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 ...
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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.
SH. Shafiei Bafti; S.A. Alavi; M. Mohajjel
Abstract
Faryab area at the southeastern part of the Sanandaj-Sirjan zone, containing the Paleozoic rocks in the internal part of Zagros Orogen, displays two folding episodes through a progressive deformation event. Axial planes of recumbent F1 folds dip moderately to the north and the ...
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Faryab area at the southeastern part of the Sanandaj-Sirjan zone, containing the Paleozoic rocks in the internal part of Zagros Orogen, displays two folding episodes through a progressive deformation event. Axial planes of recumbent F1 folds dip moderately to the north and the axes also plunge moderately to NW - SW. F1 folds were generated in a flexural-flow condition in whole lithological units. Thrust faults were produced along the overturned limbs of the F1 folds. These thrusts are most abundant in the central domain, the north of Zartorosht Au-index. At the southern edge of the central domain, displacement of large slabs of calcschist with interbedded marble were produced by these thrust faults.
Overturned limbs were cut by ductile shear zones of thrusts and development of green-schist facies in these shear zones implying the medium dips for thrusting. F2 folds were developed by co-axially refolding of F1 that are well exposed in Pasefid, Zartorosht and Zehmakan anticlines. Structural data shows the variation of F2 axis between S45W - N80W directions. Interference patterns of Z on S, M on S and S on S indicate coaxial refolding F1 by F2 (Hook Type).