نوع مقاله : مقاله پژوهشی
1 دانشیار گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران.
2 استادیار گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران.
3 کارشناس ارشد ژئومورفولوژی، گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران.
عنوان مقاله [English]
Qeshm Island is located in the southeastern Zagros salt domes and salt domes in the Persian Gulf and near the Strait of Hormuz. Relative to the tectonic structure on the Arabian-Iranian border, the region has caused the tectonic dynamics of this region. In addition, salt tectonics has had a significant impact on the morphology of the folds of the island. In the present study, for the purpose of analyzing and recognizing the tectonic effects on morphotectonics of Anticline, 4 Anticline Salakh (in the west), Kavarzin (in the north), Souza (center and south), and Giahdan (in the east) of Qeshm Island, were selected based on geomorphologic and Morphotectonics has been investigated. Geologically, the outcropped formations in Qeshm Island include the evaporative series of Hormuz as salt domes or diopters and marl, sandstone and limestone deposits. The oldest known earthquake in the area near Qeshm is 1336 AD and then the earthquake of 1361 AD with a magnitude of 5.3 magnitudes, the destruction of which was reported on Qeshm Island.
Methodology and Conclusion
The data used in this research include geological maps of the area in order to identify faults and altitudes, digital elevation data (30m DEM of the area) for preparing the location map and information map Google Earth images to measure indices and evaluate tectonic evidence of the region. With the help of the data mentioned and the GIS and Google Earth software, the morphotectonic indices of the Anticline, which include six indices, have been calculated.Also, for better visual perception, the topographic view of the study area, the presence of valleys and plains leading to the Gulf Coast, and the role of faults and lines in the prominences, the longitudinal profile of each of the 4 Anticline studied with a 3D model Each range of Anticline was drawn. To do this, the Global Mapper software has been used.
Results and discussion
In Traingular facets surfaces used for the two Anticline of Salakh and Kavarzin, the two parameters, the mean of the area and the length of the base were higher in the kavarzin Anticline, due to the presence and superiority of the limestone in this alder, which has not been able to erosion The range of these rocks (east and south east of the anticline) is much affected, but for the average slope, which is more than 3 percent (kavarzin 17 salakh 20), there is more of the faults and parallel to the rise and rise of the earth In this area, the existence of Qeshm salt dome in the alder area and west of it is more tectonic activity and in Also confirms that effective outcome on the slope.
The cause of the highest erosion in the souza Anticline is due to the loose formations (Marl and Gyps) and the presence of low faults in this area and the reason of the least erosion in the kavarzin altogether, on the contrary, is the presence of many faults and the existence of a hard limestone formation in the range To make In the case of the parameter O, which is related to the width of the valley output, the following points can be made: Any amount of this parameter is less, indicating tectonic activity and less erosion. Accordingly, the highest activity level respectively are related to the Anticline kavarzin (100), salakh (106), Giahdan (146) and Sousa (190).
In the study of the index Stream Spacing ratio, the higher the R value, the more tectonic activity is observed. In areas with higher erosion, the waterways are wider and the main drains in the sub-basins are more spacious. However, in areas where tectonics are active, young and new areas with less erosion, and parallel and near-parallel drains in the sub-basins. Based on this, the highest tectonic activity among the Anticlines is based Stream Spacing ratio index Anticline kavarzin (3.62), Salakh (2.76), souza (2.26), and Giahdan (2.13).
The results show that, based on each of the six indices, each of the 4 Anticline of Salakh, kavarzin, Souza and Giahdan is active in terms of tectonics, and it is important that wherever the density of the fault is greater, the rising of the snowfall is overcome, such as Anticline Salah and kavarzin, and Wherever the density of the fault is reduced, the erosion of the plain creates a uniformity, such as souza and Giahdan. Finally, on the basis of each of the 6 indicators, two Anticline Salakh and kavarzin are tectonically active in terms of tectonic activity and the dangers of Giahdan and Souza due to their tropical and erosion.