نوع مقاله : مقاله پژوهشی
1 استادیار گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران.
2 کارشناسی ارشد ژئومورفولوژی، گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران.
عنوان مقاله [English]
Tectonic Geomorphology is one of the Emergent Disciplinesin Geosciences; Region is very sensitive to Tectonic Process such as Faulting, One evidence of the Areasensitivityof the active tectonic processes,the watershed Shape is affected by it.Active Tectonic Basin due to Uplift is Oblong and Inactive Tectonic Basin due to Erosion is Circular.Some tectonic indicators can give researchers information about the shape of the basin.Including indicators of Basin Shape Ratio, Basin Shape and Factor, Compactness, Circular Ratio and Elongation Ratio.
Position of the Iranian plateau in the plate of Arabic, African and Eurasian Has great influence on the movements of these plates with continental crust Shelf As a result, the country has become a most dangerous and volatile environmentIn the tectonically.Hence, due to such risks is critical. The remarkable thing is that the long-term effect of active tectonic regions Before examining the hazardous occurrence and tectonic activity areas noted. One of the effects of active tectonics in the drainage basin scale Effect on the shape of the basin Thus, the area affected by tectonic activity and young because Uplift they tend to stretch And tectonically active basins lacking As a result, they become round wear. In this study, using the profiles of the basin shape ratio, shape factor, form factor, Compactness, Circular Ratio Elongation Ratio amount of Neotectonic activity in the Roodak basin Located in the north of Tehran were studied And validity of these indicators next to Common index Basin Shape ratio was measured. Results for sub watershed studies on Amameh, Garmabdar and Meygoon and Ahar indicates that although this indices Fractional Basin shape ratio sync, the study of tectonic activity watershed not used But can detect the influence of neotectonicOn watershed Drawn on the basis of active tectonic basins Be examined in conjunction with other Neotectonic indices. If the criteria strain Amameh sub basin to the Garmabdar sub basin not stretch well represented.
Key Word: Neotectonic, Basin Shape, Fault, Tectonic Hazards, Roodak Basin.
In this study, Calculating of Indices based on the shape of the basin, Confirms the active tectonics theory Based on Active Tectonic in Oblong BasinsVersus Inactive Tectonic in Circular Basins. This indicator is shown as well.In this study also, the Highest Value of Shape Factor, Compactness and Basin Shape Ratio Indices and Lowest Value of Form Factor, Circular Ratio and Elongation Ratios Owned Amameh Basin that indicate Oblong shape of Amameh Sub basin. Basin Shape Amameh also confirms this subject; Versusthe opposite of this position for Garmabdar Basin There Are. Garmabdar Basin Shape Confirms the existence of circular shape.
Result and Discussion
There is evidence of numerous works, such as broken stones on steep walls,Not been sedimentary, tectonic springs and oases such as Ahar and Amameh, Traces and fractures caused by faulting in pieces of Rocks With known faults rooted in the Central AlborzAnd many others active tectonics confirm in the Basin Roodak. Obviously, this movement influence on the Basin Shape. The results show that the indicators used in this Study Except Common indicators of Basin Shape Although the as yet Have not been used to estimate the active tectonics; Can be used for this purpose.But Maximum performance for basins that have different shapes to each other.For Example Amameh and Garmabdar Basins. About The basins are similar to each other, This Indices show Different Value. For Example Meygoon and Ahar Basins That Based on Some Indices Meygoon has Maximum number of Elongation and Based on Some Other Indices Ahar Basin Has Maximum number of Elongation. However, based on these indicators every four basins are tectonically active. But with different intensities in Those Shapeaffected. This is due to the many fault lines in the area is clear. Hence the Researcher Can Use This Indices Next to Other Indices for calculating Active Tectonic in Various Region.
To evaluate the impact of neotectonic on the BasinsInitially in the form of research libraryattempted to evaluate the effectiveness of the basin of tectonic processes Given that there are numerous faults in the area mentioned in various sources, this is a definite influence.In order to investigate further in order to find evidence of active tectonics in the regionField studies were conducted in the basin.Then, using a 2.5-meter resolution satellite imagery in Kartosat Roodak mountainous watershed boundary identified.And then through wms9.1 software and Arcgis10.0 DEM resolution of 10 m the study areaBasin and its Sub basin and its drainage Networkwas extracted.Then, using indicators of Basin Shape Neotectonic activity in the catchment area of each sub Basin Roodak was investigated.