F. Ghaemi; F. Ghaemi
Abstract
The Northern Khorasan is one of important active tectonics area. The main faults are strike slip (dextral and sinistral) and minor faults are thrust faults. Many of thrust faults are older than strike- slip faults and some of them are younger and are active now. It is because of bending of strike-slip ...
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The Northern Khorasan is one of important active tectonics area. The main faults are strike slip (dextral and sinistral) and minor faults are thrust faults. Many of thrust faults are older than strike- slip faults and some of them are younger and are active now. It is because of bending of strike-slip faults that converts, them into thrust faults. We recognized active faults based on their characteristics. In this area we have two series of tensile joints and two series of shear joints. Principal stresses have the fallowing attitudes :() - ((
)- ). Strikeslip faults can be sympathetic. For example the 1997 Bojnurd earthquake on the Yekke-shakh fault affects Baba- aman and Gharlegh faults
M. R. Moshrefi far; A. Alavi; M. Mohajjel
Abstract
In this research, separation of paleostress phases in the central part of Dehshir fault is investigated based on the study of heterogeneous fault-slip data and their related slickenside lineations. These data are measured from the Certaceous (Taft limestone), ...
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In this research, separation of paleostress phases in the central part of Dehshir fault is investigated based on the study of heterogeneous fault-slip data and their related slickenside lineations. These data are measured from the Certaceous (Taft limestone), early Eocene (Kerman conglomerate) and Eocene (Volcanics) formations. The main criteria used here to identify sense of fault-slip are stratiographic separation, accretionary mineral steps, Riedel shears and tension gash. The existing faults in the region of investigated often show two NE and NW trend in which the latter is usually dominant. Based on the study of heterogeneous fault-slip data and their related slickenside lineations and using the multiple inverse method, at least two phases are expected. These phases show that the axis of maximum principal stress, σ1, is at NE trend and that of minimum principal stress,σ3, is at NW trend. The location of σ3 usually indicates that the strike-slip and reverse strike-slip faults mostly occur in the region. In addition, the shape of the stress ellipsoid is prolate in the region.
D. Mokhtari
Abstract
Tabriz fault, oriented NW to SE, on its NW continuation that includes Mishow northern fault, is a right- lateral strike-slip fault and one of the most seismically active zones in Azerbaijan of Iran. Studies on different parts of this fault indicate that there are numerous geomorphologic ...
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Tabriz fault, oriented NW to SE, on its NW continuation that includes Mishow northern fault, is a right- lateral strike-slip fault and one of the most seismically active zones in Azerbaijan of Iran. Studies on different parts of this fault indicate that there are numerous geomorphologic features due to tectonic activities along it. Sag ponds are one of the features that in spite of their importance from geologic, geomorphologic and tectonic point of view have not been studied in this area. Therefore, this paper attempts to study several sag ponds along Tabriz and northern Mishow faults including Bostan-Abad Ghouri-ghol, Payam, Aralan, and Mishow Ghouri-ghol dry sag ponds. An introduction to sag ponds as a geomorphic effect of the strike-slip faults to recognition of active faults is the main goal of the paper.
All of these sag ponds are bounded by stike-slip and normal faults, subjects for previous investigations, field observations and geomorphic indices such as offset and deflected drainage and displaced terraces and alluvial fans. Obtained results from sag ponds and infilling of these basins by young Quaternary deposits indicate that Tabriz and northern Mishow faults are active faults, capable of generating relatively strong earthquakes in the future.
