Morphotectonic

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1 - The role of the active tectonics in geomorphic anomalies of Gorgan Rud - Gharasu basin
Agh- Atabai Nemati معصومه روستائی

The study area is located in north of eastern Alborz range. In this study, it was evaluated the pattern of neotectonic in eastern Alborz and the distribution of seismicity and geomorphic pattern of Southern Golestan province. To assess tectonic activities in 22 separat More

The study area is located in north of eastern Alborz range. In this study, it was evaluated the pattern of neotectonic in eastern Alborz and the distribution of seismicity and geomorphic pattern of Southern Golestan province. To assess tectonic activities in 22 separated subbasins, we have analysed neotectonic indices: the stream– gradient index (SL), drainage basin asymmetry (Af), reveres symmetry of topography (T), hypsometric integral (Hi), drainage basin shape (Bs) and mountain front sinuosity (Smf). The results of the analysis is accumulated and expressed as an index of relative active tectonics (Iat), which divided into four classes from relatively low to highest tectonic activity. The high class values of tectonic activity for Iat mainly occur in the south and southwest of the Gorganrud- Gharasu drainage basin, while the rest of the study area has classes of Iat suggesting moderate to low tectonic activity. The rate of tectonic activity in this area will increase from north to south. This increase can be related to the position of peaks steam gradient index along the faults and segment faults. Also value of drainage basin asymmetry is calculated for all of the subcatechments greater or less than 50 that shows tilt for each stream toward West or East. The results of this study show that the distribution of seismicity, geomorphic and tectonic movements of studied area has been affected especially by Khazar and North Alborz faults movement and thrust fault in north of Gorgan. Areas with high tectonic activity and the high measure of tilting indicate that there may be a thrust fault, with a NNE-SSW approximate trend. On the other hand, this seismicity trend may be related to a deep and relatively young thrust splay in north of the Alborz range front. Manuscript profile
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2 - Morphotectonics and Paleoseismology investigation on Sahlan Fault Fragment, NW segment of the North Tabriz Fault
الهه احمدزاده Samane Aliakbar Nazari Talebian Solaymani Azad Marzieh Faridi Masouleh

The North Tabriz Fault is one of the major strike-slip faults (trending NW-SE) in NW Iran, that trends from Sofian to Bostan Abad. Generally, the fault consists of two main fault segments. In present research, to study the last active tectonics at the North Tabriz Fault More

The North Tabriz Fault is one of the major strike-slip faults (trending NW-SE) in NW Iran, that trends from Sofian to Bostan Abad. Generally, the fault consists of two main fault segments. In present research, to study the last active tectonics at the North Tabriz Fault region, evaluated young morphotectonical features and paleoseismology of northwestern fault segment evaluated. On the basis of morphotectonic approaches on this region, horizontal slip last event (MW = 7.4, 1780 AD) are found in the ranges 3.5 ±0.5 m and vertical slip between 0 and 0.5 m. However, by attention to H/V ratio can propose that NW segment of North Tabriz Fault act as pure strike slip which confirm by new GPS data on this part of Iran. On the basis of paleoseismological researchs, by examining a wall perpendicular to the North Tabriz Fault in North Sahlan Village, four old paleoearthquakes with relative magnitude of MW = 6.4 has been detected. A young magnitude of the event, recorded in deposits of the paleoseismologic trench of the study area, close to 7 have been estimated that according to geographic and stratigraphic location, this event can be associated with historical earthquakes since 1780 AD (MW = 7.4). Manuscript profile
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3 - Assessment of the activity in the gap zone of the Rudbar Fault, based on the morphotectonic indices of the Sefidrud River, Gilan Province
Shoja Ansari

In this study the morphotectonic indices for a specified length of the Sefidrud River, which is located in the meizoseismal area of the 1990 Rudbar earthquake, have been investigated to constrain the activity of a gap between the Rudbar Fault segments. The Digital Eleva More

In this study the morphotectonic indices for a specified length of the Sefidrud River, which is located in the meizoseismal area of the 1990 Rudbar earthquake, have been investigated to constrain the activity of a gap between the Rudbar Fault segments. The Digital Elevation Model (DEM) with 30 m resolution was used to obtain the elevation data. Fifteen km of the Sefidrud River also was divided into 100 -meter segments to calculate the morphotectonic indices. The morphotectonic indices include the sinuosity (SI), stream-length gradient (SL) and river long profile. The sinuosity in this region, where the trend of the Rudbar fault cut across the river, is approximately 1-1.5 and has a lower value relative to the other segments of the river. This indicates that the uplift possibly affected this region and then indicates the high tectonic activity. The stream-length gradient in the target region is approximately >3000 and has a higher value in the region which may be related to the lithological and active tectonic effects. The high value of SL can be used for determining the regions with high potential for the landslides along the strike of the Sefidrud River. The Sefidrud long profile, in aforementioned area, has a bulge or convexity. Such convexity together with the high value of stream-length gradient can indicate that the tectonic activities are significant in this region. By comparing the morphotectonic analysis with the seismotectonic studies such as the Coulomb stress changes due to the 1990 Rudbar earthquake, in which the high stress zones were detected in this region, it can be cluded that the studied region has high tectonic activities and consequently its monitoring to prevent the seismic hazard is essential. Manuscript profile
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4 - Morphotectonic investigation of Talkhab and Tozlugol faults and formation of the Meyghan playa, Arak
leili Izadi kian نسرین پیری محمدجواد اکبری Masomeh Molaei
20.1001.1.17357128.1400.15.58.7.1

Meyghan playa near Arak city is located at the boundary of the metamorphic zone of Sanandaj- Sirjan and Urmia-Bazman volcanic zone. Two main faults of Talkhab and Tozlugol (Tabarte) play a key role in the formation of this basin by right lateral movement with northwest More

Meyghan playa near Arak city is located at the boundary of the metamorphic zone of Sanandaj- Sirjan and Urmia-Bazman volcanic zone. Two main faults of Talkhab and Tozlugol (Tabarte) play a key role in the formation of this basin by right lateral movement with northwest - southeast trend. In this study, morphotectonic indices were investigated to study the tectonic activity of these two faults. The measured indices include altimeter integral index, asymmetry index, stream length gradient index and basin shape factor. Investigating the relative active tectonics using the above mentioned indicators shows that Arak region has a relatively moderate to high activity. Particularly, the region between the two Talkhab and Tozlugol faults is more active than the other regions. The graben of the Meyghan Desert is formed due to the activity of the Takhab and Thouzlugol faults during the Pleistocene by right lateral transpresion zone. The southwestern side of the lake is in accordance with the Tozlugol fault. It seems that according to the morphometric studies of this area, the activity of the Talkhab fault is more than the Tozlugol fault and plays an important role in the formation of the Meyghan playa. Manuscript profile

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