چکیده:
Tectonic processes are major factors controlling landform development in tectonically active areas. In order to evaluate quantitative measurement of tectonic activities in the Alamarvdasht basin in the south of Iran, six different morphological indices including stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), drainage basin shape (Bs) and mountain-front sinuosity (Smf) were calculated. These indices were combined to generate the relative active tectonics index (IAT) and the study area was divided into three classes: high, moderate and low relative tectonic activity based on IAT values. The results of IAT index showed that high and moderate tectonic activity areas are located near the main faults and anticlines. The results are also consistent with geology and field observations on landforms and GPS data of Lamerd geodynamics station. GPS data shows subsidence and north-eastern movement in the basin because of convergence between the Arabian and Eurasian plates in the Zagros Mountains zone.
خلاصه ماشینی:
"In order to evaluate quantitative measurement of tectonic activities in the Alamarvdasht basin in the south of Iran, six different morphological indices including stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), drainage basin shape (Bs) and mountain-front sinuosity (Smf) were calculated.
These indices were combined to generate the relative active tectonics index (IAT) and the study area was divided into three classes: high, moderate and low relative tectonic activity based on IAT values.
The results of IAT index showed that high and moderate tectonic activity areas are located near the main faults and anticlines.
Then the following geomorphic indices including stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width-valley height ratio (Vf), drainage basin shape (Bs) and mountain-front sinuosity (Smf) were calculated.
Basin shape index (Bs) Relatively young drainage basins in active tectonics areas tend to be elongated in shape normal to the topographic slope of a mountain.
Relatively young drainage basins in tectonically active areas tend to be elongated in shape, normal to the topographic slope of a mountain (Bull & McFadden, 1977).
Since the whole area of Alamarvdasht plain is covered by the Quaternary deposits along the main river and there is no change in rock resistance, the Alamarvdasht basin SL index values and anomalies represent the effect of tectonic activity of strike-slip faults but in the sub- basins with different rock resistance, this index is effected by rock strength changes of different geological formations too."