Economic Geology
shahriar keshtgar; Sasan Bagheri; shahriar keshtgar
Abstract
Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, ...
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Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, are andesitic basalt, diabase, microgabbro and dacite that were intruded by the late cretaceous granitoids. The volcanic rocks have characteristics of the calc-alkaline to tholeiitic magmatic series. The spider patterns normalized to N-MORB and Chondrite is similar to the ones belong to the supra-subduction zone (SSZ) and Islanc arcs ( IAT). The EPMA studies on the key minerals in volcanic rocks such as clinopyroxene , brought the same results. The pribable presence of an island-arc chain in the Sistan Suture Zone, which some of its parts are considered here as the MVPC, is comparable to continuation of the pakistanian Chagai-Raskoh and Kuhistan Cretaceous-Eocene island-arc/s in east. Considering this reality, we must expect to have a larger ocean much wider than what was already proposed for the Sistan Ocean as a narrow oceanic seaway in Continental rifting setting.
H Yazdanpanah; M.M Khatib; H Nazari; E Gholami
Abstract
A model suggests the current shear, which originated about 5 Ma ago, has been accommodated by strike-slip faulting within and along the margins of the Lut area. The measured Quaternary slip rate along the Nehbandan fault system to the east and the Nayband fault system to the west margins of the Lut area ...
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A model suggests the current shear, which originated about 5 Ma ago, has been accommodated by strike-slip faulting within and along the margins of the Lut area. The measured Quaternary slip rate along the Nehbandan fault system to the east and the Nayband fault system to the west margins of the Lut area is ~ 5 and ~ 1.7±0.3 mm/year, respectively. Therefore, the observed slip rate is shown to increase from west to the east margin. This has resulted in the development of a dextral strike-slip shear system with heterogeneous slip rate across the Lut area. We have used satellite images, field observations, aeromagnetic data and analogue modeling to measure Cenozoic strain distribution and slip-rate changes in the Lut area. Results show direct linkage between deformation distribution and slip rate changes along the margins of the Lut area.
F Porghiasian; E Gholami; M.M Khatib
Abstract
In this study, value of shear strain for the Koch fault zone was determined based on the angle of foliations with the edge of the Koch fault zone. The Koch fault zone with N-S trend is located in northeast of Birjand, at the end northwest of the Sistan structural zone. In the Koch fault zone shear strain(γ) ...
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In this study, value of shear strain for the Koch fault zone was determined based on the angle of foliations with the edge of the Koch fault zone. The Koch fault zone with N-S trend is located in northeast of Birjand, at the end northwest of the Sistan structural zone. In the Koch fault zone shear strain(γ) was calculated based on the foliations, which are from the types of fracture cleavage. Shear strain in central part of the Koch fault zone reaches to 4 degrees, its maximum. The value of shear strain reaches to 2 degrees in southern and northern parts of the Koch fault. The value of shear strain decreases from central part of the Koch fault towards the northern and southern parts. The latter indicates the growth of the fault from the central to the northern and southern parts.
