Comparison of Strain Ellipsoid Shape in the South of Ardabil Range (NW), Based on the Results of the Magnetic Susceptibility Anisotropy and Paleostress Methods

In recent years, the method of magnetic survey as one of the new techniques in geological and geophysical studies is known. In this study to determine the shape of the stress field of the two methods, Anisotropy of Magnetic Susceptibility (AMS) and paleostress?have been used. Paleomagnetism is the characteristics of magnetic rocks. Some issues in associated with the past places of continental and oceanic plates can be solved. AMS is one of the paleomagnetism methods that pay to measurement of parameters (which are reflector of the magnetic fabrics rocks). It is presenting an ellipsoid with three-axis perpendicular to each other that defines magnetic ellipsoid. In this regard, the number of 12 stations in different rocks (Jurassic to Quaternary) in the southern region of Ardebil sampling was conducted. In this connection, the study of magnetic fabrics has shown an elliptical magnetic susceptibility with the prolate shape. For the separation of paleostress phases in the Khalkhal area using the analysis of the paleostress based on the study of heterogeneous fault-slip data and sliding lineaments. Firstly, data were picked from 10 stations, and after their analysis, the elliptical shape (prolate) has been determinated. The shape of the ellipsoid, based on AMS and paleostress methods and their results show that in both methods the shape of the stress field is prolate.

Investigation of T Factor Variations along Atrak River to the Caspian Sea

The study area has located on Atrak river basin in the Iran-Turkmenistan border zone that is the greatest river on the southeastern margin of Caspian Sea. The study area was divided into 56 sub-basins and then T factors were calculated for all streams of the Atrak river. T factor is a geomorphic index for tilting identification by active tectonics. Our results show that, there are low, moderate and high relative tectonic activities levels. Low relative tectonic activities level has been found in sub-basins No. 1, 2, 3, 4, 10, 23, 25, 41 and 51, moderate relative tectonic activities level has been found in sub-basins No. 5, 6, 7, 8, 13, 14, 17, 18, 19, 20, 21, 24, 28, 29, 30, 31, 32, 34, 35, 39, 40, 42, 43, 46, 47,48, 49, 50, 52, 53, 55 and 56 and high relative tectonic activities level has been found in sub-basins No. 9, 11, 12, 15, 16, 22, 26, 27, 33, 36, 37, 38, 44, 45 and 54. Also, most part of the study area has got moderate tectonic activity that it is compatible with its tectonic setting on the Kopetdagh belt in Iran. It is shows that some sub-basins on the western parts of study area that river has got west-east trending, are more active. But, some sub-basins on the eastern parts of study area that river has got northwest-southeast trending, are less active. It means that migration direction of the most streams are toward north and south and the major faults and folds in the western parts of study area caused river tilting be perpendicular to structural trend. This variation along the most important river on the northeastern part of Iran was analyzed for the first time in this research.

Active Tectonics of the Saymareh-Karkheh River Basin (Northwest of Persian Gulf, Iran)

Active tectonics is an indicator of recent movement of mountains and landscapes evolution for regions affected by current tectonic activity. The Saymareh-Karkheh river basin is located on the Zagros Mountain in the west Iran. The Zagros Mountain is an orogenic belt that is formed by the collision between the Eurasian and Arabian plates during Cenozoic. Active tectonics has analyzed by measurement of six geomorphic indices (hypsometric integral, basin asymmetry factor, basin shape, the stream length-gradient, mountain-front sinuosity and valley floor width-height ratio) which they combined to index of active tectonics (Iat). Based on values of this index, the Saymareh-Karkheh river basin was divided into high (Class 2, 18.8%), moderate (Class 3, 70.3%), and low (Class 4, 10.9%) relative tectonic activity parts. The above results confirm the usefulness of geomorphic analyses for regional assessment of active tectonics they are compatible with differential tectonic activity in the High Zagros and Zagros fold and thrust belt. Also, it was revealed that geomorphic indices and using of GIS technics are very useful to investigation of active tectonics in the mountain areas.

The Transverse Topographic Symmetry Factor of Darakeh Stream in the North Tehran, Iran

The study area?is located in the north Tehran, Iran. Calculation of transverse topographic symmetry factor (T) is suitable for rapid assessment of active tectonics. Therefore, transverse topographic symmetry factors have?beencalculated for the Darakeh stream. The study area is located in the Tehran Piedmont and transverse topographic symmetry factor?is calculated for it. Based on values of this index, there is high relative tectonic activity level. This condition can be related to existence of a blind north-south striking fault which it may be buried by alluvium of the Darakeh stream. Dendritic drainage pattern of Darakeh stream and the fact that the western tributaries are longer than the eastern tributaries provide indirect evidence of ground tilting toward the east. Also, based on our results, most part of the study area have got high tectonic activity that it is compatible with its tectonic setting on the Tehran in north Iran.