S. Dashti Chandanagh; M. R. Sheikholeslami; J. Taheri
Abstract
This study was conducted to determine the deformation pattern of the Mashhad metamorphic rocks which results from the convergence between Turan and Central Iran plates and closure of Paleotethys Ocean during Early Cimmerian event. The results of 2D and 3D strain analysis show that the maximum deformation ...
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This study was conducted to determine the deformation pattern of the Mashhad metamorphic rocks which results from the convergence between Turan and Central Iran plates and closure of Paleotethys Ocean during Early Cimmerian event. The results of 2D and 3D strain analysis show that the maximum deformation is concentrated in the central part of the study area and most strain shape parameters (K) obtained from oriented samples are located within the flattening part of the Flinn diagram. Strain intensity parameter in most cases is less than 0.5 and a maximum strain occurred in the central part which is reduced towards the margins. This is the most characteristic of the typical shear zones in which, the maximum strain is concentrated on the central part. Calculated vorticity numbers is ranged between 0.2 to 1 indicating the presence of both pure shear and simple shear during a transpressional regional deformation.
M.R Sheikholeslami
Abstract
Different characteristics of the rock units and their stratigraphic relationships, as well as magmatic and metamorphic activities in the southern part of the Sanandaj-Sirjan Zone resulted in identification of different tectono-stratigraphic units based on their tectonic environments reflecting the opening ...
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Different characteristics of the rock units and their stratigraphic relationships, as well as magmatic and metamorphic activities in the southern part of the Sanandaj-Sirjan Zone resulted in identification of different tectono-stratigraphic units based on their tectonic environments reflecting the opening and closure of the Neotethys Ocean in southern Iran. The major tectono-stratigraphic units identified in this study are as follows: sediments deposited in the aulacogen setting in southern part of the Central Iranian platform of Paleozoic to Middle Triassic age; Triassic volcanic rocks and turbiditic sediments; low-grade flysch-type sediments of Jurassic-Early Cretaceous age deposited in a forearc basin; Lower Cretaceous carbonate platform sediments; suture zone-related rocks containing ophiolite, radilolarite and glaucophane schists; Tertiary flysch-type sediments containing exotic blocks of Lower Cretaceous carbonate, ophiolite and of the Zagros Formations formed over the edge of High Zagros zone; retro-arc foreland sediments of Central Iran which unconformably overlie the deformed rocks of northeastern part of the area; and finally post-orogenic molasse-type sediments resulted from post uplift erosion of the Zagros orogeny, deposited in the internal and marginal parts of the southern Sanandaj-Sirjan zone.
M Ramazani; M. R. Ghassemi; A Zanchi; M. R Sheikholeslami
Abstract
Theerosional window of Aghdarband , located in NE Iran to the SE of Mashhad is a unique place for study of the Eo-Cimmerian event. This event (Late Triassic-Middle Jurassic) resulted from clousureof thePaleothetys ocean and collision between the Iran and Turan plates. These two plates were separated ...
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Theerosional window of Aghdarband , located in NE Iran to the SE of Mashhad is a unique place for study of the Eo-Cimmerian event. This event (Late Triassic-Middle Jurassic) resulted from clousureof thePaleothetys ocean and collision between the Iran and Turan plates. These two plates were separated from each other before Late Triassic, and therefore they had different tectonic and sedimentary histories. At this time the Aghdarband area was located on active margin of Eurasia, and therefore the units that are exposed in the erosional wiondow of Aghdarband have basic differences with their counterparts in other places of Iran. During the Eo-Cimmerian event, the Aghdarband area was affected by a sinistraltranspression. Strain in this transpressional zone was intensively partitioned, and three major structural domains with different structural characteristics were formed in it. A sinistral strike-slip fault zone and an imbricate thrust fault zone were formed respectively in northern and southern part of the Aghdarband area. Development of this transpressional zone may be attributed to the oblique convergence between Iran and Turan plates during above mentioned time interval.
M Ramazani; M. R. Ghassemi; A. Zanchi; M. R. Sheikholeslami
Abstract
The Dare Anjir and Fariman complexes in NE of Iran are considered as remnants. These complexes considering were located close to Palaeotethys suture zone, and thus they record its structural evolution. considering structural and petrological evidences and against previous opinions that considered Fariman ...
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The Dare Anjir and Fariman complexes in NE of Iran are considered as remnants. These complexes considering were located close to Palaeotethys suture zone, and thus they record its structural evolution. considering structural and petrological evidences and against previous opinions that considered Fariman complex as an accretionary wedge, these complexes seem to be remnants of a magmatic arc that formed as a result of subduction of the Palaeotethys beneath Turan plate in Permian-Triassic. Fariman complex may be divided into upper and lower parts. At least two deformation phases may be recognized in upper part of the Fariman complex. second deformation phase caused creation fault propagation folds, and probably was coeval with main deformation phase of Eo-Cimmerian that affected Aghdarband basin. Deformation style in Fariman and DareAnjir complex is compatible with strain partitioning proposed for Aghdarband transpressional zone as a result of oblique convergence between Iran and Turan during Eo-Cimmerian event.
