Geometric Analysis of Salt Diapirs using Geomorphologic Indices(Case Study: Salt Diapirs in Lar Region of Fars Province)

During the past two decades, extracting geomorphic indices using digital elevation models in the GIS environment has been addressed as a quick and accurate method to analyze landforms, so that these indices have been used to quickly evaluate the recent tectonic activity in a particular area. The present study aimed to evaluate the active tectonic of salt diapirs located on south-eastern Zagros in Lar region of Fars province, by measuring the hypsometric integral (Hi), basin height (Bh) circularity ratio (Rc), elongation ratio (Re), drainage density (Dd), bifurcation ratio (Rb), mean length of first-order streams (LN1), stream frequency (Fs), alluvial fan’s width to length ratio (W/L), and the sweep angle (S). First, the study area was extracted using digital elevation model. After calculating the indices in salt diapirs, the results reveal that the best correlation is between the hypsometric parameter and the diapirs area, indicating that the hypsometric integral is a good indicator for classifying age of diapirs. In addition, the mean length of the first-order stream is a good indicator for dividing the diapirs from age viewpoint (youth and old). It was found that the drainage density index, bifurcation ratio, drainage frequency, the indices of the alluvial fans around the diapirs  such as the sweep angle, width to length ratio, and slope have no significant relationship with the hypsometric integral and the age of the diapirs. The lack of a significant relationship was due to the complex structure of the salt diapirs and their movements, which disrupted the morphometry of draiange systems of the study area.