Morphotectonic

Open Access Article

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

Open Access Article

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

Open Access Article

3 - Morphotectonic study of a fault tip zone around Qozlu (SE part of the North Tabriz fault)
Alireza Yousefi-Bavil Moayyed

Fault traces within the Qozlu fault tip zone, located at the southeast end of a segment of the North Tabriz fault, which reaches to the Bozqush deformation zone, represents the formation of a horsetail structure. There is, however, no information about the type of this More

Fault traces within the Qozlu fault tip zone, located at the southeast end of a segment of the North Tabriz fault, which reaches to the Bozqush deformation zone, represents the formation of a horsetail structure. There is, however, no information about the type of this structure or its deformation pattern. In this regard, study of topography (analysis of the relative elevation difference at two scales—within the overall deformation zone and in buffer zones along streams flowing within the zone), surface slope, asymmetry factor, and geological information indicate that: 1) the fault tip zone is a contractional horsetail splay; 2) a compressional tectonic regime is dominant within the fault tip zone and the trend of maximum compression is N20W-S20E; 3) two different fault zones with maximum and minimum tectonic activities are recognised along two streams within the fault tip zone ; 4) the overall dip-slip component within the stream-related fault zones is reverse or thrust. These results provide significant information about tectonics of the Qozlu fault tip zone and improve our knowledge of deformation within the North Tabriz fault zone. This study, also, demonstrates the importance of using stream longitudinal swath profiles to obtain tectonic information directly from topography. Manuscript profile

Open Access Article

4 - Mechanism of young deformation in Tehran plain: a combination of field observation and analog modeling
Hourieh AliBeygi Morteza Talebian Manouchehr Ghoreshi

The capital city of Tehran is located to the south of central Alborz. The North Tehran fault, as the main structure of this region, perched on the northern part of the city and separate alluvial fans from volcanic rocks of the Alborz. There are several other faults w More

The capital city of Tehran is located to the south of central Alborz. The North Tehran fault, as the main structure of this region, perched on the northern part of the city and separate alluvial fans from volcanic rocks of the Alborz. There are several other faults within the city which seem to be structurally related to the North Tehran fault. Geomorphic study of fans and river deposits suggest that most of these faults are active and taking up both left-lateral and shortening in a wider zone to the south of North Tehran fault. In addition to faults there is distinct folding within the Tehran plain. Field observation along road cuts which cross these structures suggest that young folding in Tehran plain are active and escalate due to the activities of the underlying faults. There is little evidence of rupture in front of these structures and thus most of them are considered as blind faulting. The trend of these structures is oblique to the North Tehran fault which is probably due to distribution of left lateral deformation in wider zone within the Tehran plain. The distance between active folds and the North Tehran fault increase from west to east. Analog modelings were carried out to study the effect of thickness and slop of deposits on position and trend of structures within the Tehran plain. Results from these experiences show that geometry, orientation and distance between structures is probably controlled by oblique shortening of the zone, as well as increase in thickness and slope of the sedimentary deposits. Manuscript profile

Open Access Article

5 - 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

Open Access Article

6 - Morphotectonic investigation of Talkhab and Tozlugol faults and formation of the Meyghan playa, Arak
leili Izadi kian نسرین پیری محمدجواد اکبری Masomeh Molaei

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

List of Articles Morphotectonic

Rimag

Links

Related Centers

Technical Support

Official pages