aziz rahimi

Until now comprehensive studies have been carried out by various researchers on the structural and geometric model of the Mosha-North Tehran fault system. As a structural lozenge with an general WNW- ESE trend, this fault system is located in the southern flank of Alborz Mountain range where is considered a part of Alpine-Himalayan orogenic belt. The mentioned system consists of Mosha fault zone to the NNE and North Tehran fault zone to the SSW which has experienced various left-lateral or right-lateral strike slip mechanisms with contractional or extensional components during the geological time. NW-striking thrusts, the Purkan- Vardij Thrust (PVT) and Emamzadeh-Davud Fault (EDF) are also considered as other remarkable structural features of the region. The studied structural zone has gone through several uplifts and subsidences from the Mesozoic to the present day. This means that in the study area, the phenomenon of inversion tectonics has occurred many times and so, extensional and contractional regimes have interchanges alternately to each other. For example, during Oligo-Miocene, due to the northwestward movement of the South Caspian Basin with respect to the Eurasia, inversion tectonics turned a transtensional (right- lateral with extensional component) environment into a transpressional (left- lateral with small contractional component) one. In this research, a new structural model has been presented, based on which the study area is formed by an interchangeable half-negative flower structure and half-positive flower structure.

Structurally, the Tarom Metallogenic Zone is located in an NW-SE trending anticline with 50 km wave-lenght, consists of the Karaj formation equivalent units and Neogene red beds. This anticline was created during the Alborz orogen formation- related phase has multiple fractures with NW-SE, NE-SW, and E-W trend. Detailed mesoscopic and microscopic investigations of the existing fractures for studying their propagations during folding, including their relative age, sequential deformation of the fractures in various beds, distribution of the fractures, and their changes during the following geological events, were performed many times. Comparison of various fracture patterns in folded layers not only illuminates the brittle deformation successions but also resulted in the detection of the main fold formation mechanism of the studied area. Based on the existing evidence at limbs of the anticline including 1- The existence of parasitic folds in soft layers, 2- Creation of layer- parallel shearing related strata-bound fractures in soft layers on various scales. Dyke intrusion into pre-existing fractures at fold limbs, preferentially has been happened in soft beds, especially in the Karaj formation equivalents pencil shales. While at the hinge zone, they have been created in hard layers, for example, andesite and basalt. The flexural slip mechanism is proposed for the Tarom Anticline.

The central part of Fars province of the Zagros fold – thrust belt has complex geological structure and geometry probably due to activity of major basement strike slip faults. In this research numerical modelling were used considering different scenarios of the possible roles of Sarvestan, Sabz-Pushan and Nezam-Abad faults for strain distribution modelling. Models were constructed using FEM method and Mathematica software applying local convergence direction of Iranian and Arabian plates in the Fars area and different scenarios of presence of each of three faults. Results revealed vital role of the Nezam-Abad fault in coeval activity of Sarvestan and Sabz-Pushan faults at the time in forming of the geometry of the study area.

Recent studies in animal models indicate that recombinant human erythropoietin (rhEPO) is very effective in enhancing neurological recovery after spinal cord injury (SCI). We aimed to evaluate the effect of rhEPO plus methylprednisolone sodium succinate (MPSS) compared to MPSS alone to improve neurological function of patients after SCI in a randomized clinical trial. During a 15-month period 30 patients presenting to emergency departments of two university affiliated hospitals within less than 6 hours after acute SCI were randomized to two groups. Both groups received MPSS 30 mg/kg initially and 5.4 mg/kg every hour till 23 hours if admitted within 3 hours and till 47 hours if recruited within 3-6 hours after injury. Group EPO also received 500unit/kg rhEPO on admission and another 500 unit/kg 24 hours later instead of placebo in group MPSS. Neurologic evaluation was performed on admission, 24, 48, 72 hours and one and 6 months later. Range of patients’ age was 18-65 years. There was no significant difference between patients receiving two types of treatment in neurological exam on admission (P=0.125), 24 hours after admission (P=0.108) and 48 hours after admission (P=0.085). However, one week (P=0.046), one month (P=0.021) and six months (P=0.018) after admission these differences were significant. MPSS plus rhEPO started within 6 hours after acute spinal injury may be more effective than MPSS plus placebo in improvement of neurologic dysfunction. More studies with larger sample sizes are warranted.

The present study investigates the crystal preferred orientation (CPO) of quartz crystals in psammitic rocks to ascertain the deformation mechanism using electron backscatter diffraction (EBSD) on quartz crystals from north of the Renvyle-Bofin Slide (RBS) near Letterfrack in western Ireland. Complete crystallographic orientations were determined for several thousand individual quartz crystals in psammite samples to provide a dataset for exploring the active deformation mechanis (s). Quartz crystallographic orientations are plotted as pole figures and contour diagrams in <0001> and <11¯20> directions. Quartz c-axis patterns show maxima in the Y axis of the pole figure, which can be explained by the dominance of prism gliding, indicating that dislocation creep was the dominant deformation mechanism.