جستجوی مقالات مرتبط با کلیدواژه « تنش دیرین » در نشریات گروه « میان رشته ای »

The vein-type Qole-Kaftaran Pb-Zn and Cu deposit with middle Eocene volcanic host rock, located at the easternmost edge of the Toroud-Chah Shirin metallogenic belt, is chosen to characterize its structural architecture and further investigate the linkage between structures and ore-mineralization. The Qole-Kaftaran deposit is also situated at 20 km north of the active basement Toroud fault zone. To this end, field base structural study is integrated with remote sensing and ICP-OES geochemical analysis is used. Variable strikes of faults and fractures are propagated in the study area while a NE-SW strike as the significant fault trend is identified in the frequency aspect. This kind of propagation of diverse fault strikes can be interpreted as relatively tectonic maturity in the study area. Brittle and ductile derived- Paleo-stress results suggest an old almost vertical maximum compression direction (with possible age of post-Eocene- Early Miocene) and a post-Early Miocene horizontal NW-SE- directed maximum compression direction. Our result also points to the direct controlling impact of brittle structures on the distribution of alteration and Pb-Zn and Cu mineralization. In which, alteration and vein-type Pb-Zn and Cu mineralization are arranged along and at the hanging wall of the NE-SW extensional faults and grabens.

In the study area, which is located in the south of Salafchegan, there is a series of intermediate to acidic dykes that have penetrated in two stages of eruption in the Lapilli tuff units and the dark gray andesitic section. according to the age of the host rocks, the injection time of these dykes was late Miocene onwards. In this study, changes in the position of long-term stress axes in this area have been investigated using analysis of slickenline data and slickenside as well as long-term stress trajectories based on dykes’ trend from Miocene onwards. By using the position of the dykes in the area and analyzing the long-term stress data with inversion method, changes in the trend of the main stress axes from Neogene or Plio-Quaternary have indicated, so that the maximum stress direction from north-south direction at the end of Miocene to north east-southwest changed during the Pliocene-Quaternary. This change in trend could be due to the clockwise rotation of the South Caspian block, the impact of which was not limited to Alborz and was also effective in Central Iran. This effect has recently been reported in other studies in the area of the Kushk fault system.

The Kashan fault zone is located 30 km Southeast of Kashan with strike NW-SE and 80 km lengt that propagated in the middle part of Urumieh-Dokhtar magmatic arc. This fault zone intersects Eocene-volcanic intrusive, Oligocene conglomerates, Oligo-Miocene carbonate masses, Neogene and Quaternary sedimentary Units. In this research, reconstruction of paleo and neo-stress and structural evolution of Kashan fault zone has been assessed.  The collected structural data indicates the NW-SE trend and right-lateral transpression for main Kashan fault as the main fault zone in the region. The result of paleo-stress inversion and collected structural data indicate that after likely Middle Miocene (ca. Upper Miocene) the regional stress regime has been changed in which the direction of the maximum compression changed from NE-SW to N-S. The new N-S directed maximum compression caused the propagation of the E-W trending folds of the Neogene sediments and right-lateral kinematics of Kashan fault zone in the area. Furthermore, new N-S directed maximum compression formed the N-S trending grabens that have been filled by Pliocene and Quaternary detrital deposits.

The study area is exposed in the western margin of the Zahedan dextral strike-slip fault in eastern part of Sistan suture zone. This study investigates the situation of paleo-stress field based on heterogeneous fault slip data and slip-lines in Eocene-Oligocene limestone blocks. The results show the position of the three axes s 1 =45/53,  s 2 =207/35, s 3 =303/09. Based on the "right Dihedron" and "rotational optimization" methods, R¢= R (F)=0.43 , which represents the simultaneous compressional - shear stress component in eastern Sistan fold and thrust belt. Accompaniment of tensional structures such as boudinage, shear fractures and Normal faulting, indicate local Tensional stress whith  N340 direction. This results, show the occurrence of a progressive deformational phases and rotational displacement of the internal elements in this right-lateral strike-slip fault.  The local maximum tensional stress direction in this area, rotated clockwise direction, about 25° from Eocene  to recent time. The location of Ghargharook area near the fault-bent, along the Zahedan dextral strike-slip fault, can be caused  to clockwise rotation of  principal stress axis.

Study area (Shekarab Mountains) is located in Sistan suture zone. The aim of this research is to investigate the variation of stress pattern (direction of stress tensors and stress ellipsoids shape) in Neogene units, Paleogene units and older units. In this research characteristics of brittle structures (faults) were interpreted using Win-Tensor software. Structural analysis and analysis of Steps of applied Paleo stress in Shekarab Mountains indicate that in Cretaceous time stress regime operation tectonic was pressure with the direction of the main stress axes σ1=337/26, σ2=070/06, σ3=172/64 and stress ratio was 0.1 which caused the uplifting of peridotites and ophiolites in eastern part of study area. The second step of stress has been strike slip and transpressive with the direction of the main stress axes σ1=003/31, σ2=110/26, σ3=232/47 and stress ratio was 0.29, more exhumation of igneous units is related to in the eastern part of Shekarab Mountains in these regions units' stress regime has been displaced locally from strike slip to transpressive that is due to local changes of stress direction in this regions. The third step of stress regime of in Shekarab Mountains is strike slip with the direction of the main stress axes σ1=060/10, σ2=227/72, σ3=152/08 and stress ratio 0.5. Results of stress analysis indicate that major stress axis (σ1) in Cretaceous units had N337 trend, in Eocene units had N003 trend and in Quaternary units has N060 trend.