نوع مقاله: مقاله پژوهشی
نویسندگان
1 دانشگاه تربیت مدرس، دانشکده علوم پایه، گروه زمینشناسی، تهران، ایران
2 مؤسسه تحقیقات علوم و فنون زمین، تهران، ایران
3 دانشگاه بیرجند، گروه زمینشناسی، بیرجند، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Right lateral shear between Central Iran and Afghanestan caused activity of N-S and NW-SE fault zones in eastern Iran. Faults interaction effect on creation of restraining zones and out-crop of ophiolitic rocks along fault zones. Study of geometric and kinematic of structures approache to recognition of structural evolution in fault zones of North-North East Lut plain (north part of Sistan structural zone).
The activation of different structural trends in eastern Iran , Sistan zone , causes a deformation style which is significant different from nearby structural zones. This is referred to the interaction of faults with dominant strike slip mechanism and different N-S and NW-SE trends. This interaction with the greater effect of N-S trends causes development of restraining zones and curved fold axial trends in area between the en-echelon areas of the N-S tending faults.
From point of view of structural geology the study area could be divided in two main parts:
A) Activity of N-S strike slip right-lateral fault zones construct wall damage zones and tip damage zones. En-echelon N-S faults construct link damage zones with ophiolitic out-crops in the overlap area (such as Kasrab and Torshab).
B) Fault zones with NW-SE trend, have right-lateral shear with compressional component mechanism (such as SE Birjand and SE Qaen) that has resulted to a broad and continuous out-crops of ophiolitic rocks. Shortening of folded sedimentary rocks (Tertiary) increased in eastern Sahlabad (Hosseinabad, Pureng, Chakhoo, Shourak, Marghzar, Zahab)from north to south. As an accepted theory displacement increase toward the center part of faults, that could be seen Shooshk- Cheshmehzangi fault zone. This suggests that shortening is related to the fault movement. Unconformity between Tertiary and Cretaceous rocks, out-crop of ophiolitic rocks in the compression area, existence of NE-SW compressional axes along two major trends and growing of fault damage zones in the crossing of two major trends in the NNE Lut plain, demonstrate that major mentioned trends had contemporaneous activity. In the restraining zones , thrust faults causes surface emplacement of older ophiolitic rocks. The more exposure of these older rocks and presence of thrust faults in northern portion of the study area where NW-SE trending faults are abundant, imply the greater effect of the N-S trending faults. Since the major shortening axes in the Sistan zone are considered to be constant , increase in deformation through shortening measurements of the folds also constrain the greater effect of the N-S trending faults.
کلیدواژهها [English]
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