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- Figure (5.5)
- Figure (5.6)
| Figure (5.4): (a) The lineament map from the panchromatic, (b) table of statistics, (c) frequency diagram of the lineament distribution as a function of length, and (d) directional roses.
The lineaments derived from SRTM around 1115 (Figure 12-a) range from 530 m to 5657 km, with an average length of 3364417 m. The class with lengths between 981 m and 1.5 km (60–80%) dominates the lineaments (Figure 5.5-c). The directional diagram (Figure 5.5-d) shows two main routes, NW-SE and approximately E-W. All directional roses of PCA1, the panchromatic band, and STRM have similar patches showing NW-SE dominance. This orientation corresponds to the major faults shown in the structural map of the research area (Figure 5.10). Figure (5.5): (a) The lineament map from the STRM digital terrain module,(b) table of statistics, (c) frequency diagram of the lineament distribution as a function of length, and (d) directional roses. The density maps show the places where the lineaments are most pronounced. In the Northwest-Southeast and Southern parts of the area, all-directional roses of PCA1, the panchromatic band, and STRM have similar patches showing NW-SE dominance. This orientation corresponds to the major faults indicated in the geologic maps of the study area. (Figure 5.6) shows the highest densities. As this is one of the areas that has undergone numerous orogenic cycles, the topography in this area is highly fractured. The density maps created with PCA1, the panchromatic band, and STRM (Figure 5.6, b, c, and d, respectively) are incredibly close to the map of the main fault (Figure 5.6-a). Figure (5.6): The density map of (a) the major faults in the study area, (b) Lineaments of the PCA1, (c) lineaments of the panchromatic band, and (d) lineaments of the digital terrain modulus STRM. According to (Alavi M 2008), three families dominate the distribution of lineaments in this area. The direction of the essential family varies between NW-SE, NE-SW to E-W, and N-S, which is consistent with the general direction of the major faults. The structure of the first directional group is associated with the latest Neoproterozoic and earliest Cambrian (550–540 Ma). These faults have displaced Pan-African structures within the Arabian Shield to the northeast. The Recent Main Fault (MRF) and other blind faults that extend from northwest to southeast are part of the Zagros Orogen (NW-SE). The NE-SW to E-W oriented group, formed during the Permian and Triassic opening of the Neo-Tethys Ocean, represents transformation faults. The third group comprises structures formed during the pan-African orogen (670-570 Ma). Examples of these faults are ZFTBs that run in an N-S direction. Based on the correlation of our remote sensing results, we can see that all data sets provide similar or identical results. We used geologic maps of major faults in the target region to confirm our results. In addition, we rely on two other aspects that play a role in validating these conclusions. The first is the lithological map, and the second is the comparison of the lineaments with the slope map. When the lineaments are superimposed on the lithological map of the study region, we can see that most of the lineaments are concentrated in the areas composed of competent rocks. In contrast, the lineaments become weaker in the less complicated and brittle formations. In the NW-SE trending surface anticlines, which form “whaleback” limestones that are mostly resistant, there is a conspicuous concentration of lineaments in this area. The Oligocene and Miocene sandstones and conglomerates of Agha Jari and Bakhtyari in the north contain a high concentration of lineaments, while the faintly recognizable geological lineaments are found in the friable Cretaceous to Quaternary formations (silts, sandstones, marls, and boulders) (see Figure 5.7). Figure (5.7): The superposition of the lineaments on the lithological map of the study area (National Iranian Oil Company (NIOC 2010); Modified after (Ashayeri et al., 2020)). The morphology and geomorphology of the land are most probably caused by tectonic processes leading to the dips and depressions created by the movement of faults. It becomes clear by comparing the lineaments with the slope maps, one of the validations of lineaments. The slope maps were created from the digital terrain module (Figure 5.8) with the lineaments from the PCA1, the panchromatic band, and the STRM. The overlay shows that most of the lineaments are concentrated in areas with steep slopes and substantial variations in topographic profile, especially in the southwest (Sarpol Zahab) and the northeastern part. In contrast, the areas with low slopes (the central area) show a decrease in lineaments. Figure (5.8): The superposition of the lineaments on the slope map (a) major faults in the study area, (b) lineament of the band PC1, (c) lineament of the panchromatic, and (d) lineament of SRTM. FoldsThe SFB's short-wavelength topography and surface structure are characterized by parallel anticlines and synclines. These folds were previously known as detachment folds caused by buckles along the Hormuz Salt (Colman-Sadd, 1978). Despite recent structural studies that show shallower décollements in the middle, sedimentary cover may contribute to surface folding, possibly inheriting from normal faults on the stretched Arabian continental margin, prevalence of strike-slip faulting in the central SFB (Berberian, 1995; Morteza and James, 2004; Tatar et al., 2004). McQuarrie (2004) proposes a different interpretation (which balances cross sections of observed surface geology): fault propagation folding occurs over steep reverse faults that branch upward from a salt detachment in Hormuz. Additionally, Hormuz diapirism may play a role in localizing this folding and faulting, especially in the eastern Fars Arc, where salt plugs are most prevalent (Jahani et al., 2009). We have interpreted the fold structures from false color composites 7, 5, and 2. Folds are commonly identified as banded features or circular and elongated bedding lines with remarkable symmetry (Figure 5.9). Folded bedding triangle planes or monoclinal mountains have symmetry along their interface. When the lithologic distinctions between a fold's strata are obvious, micro-topography, vegetation, and banded textures show symmetric recurrence. The hinge zone of a fold always has a curved bedding plane, but bedding triangle planes seem distorted, resulting in a U-shaped, curved, or other geometric form on the image. Figure (5.9): Interpreted the fold on Landsat OLI image RGB753. Black lines are faults; surface projections of Berberian's (1995) “master blind thrusts” are dashed (DEF = Dezful Embayment Fault; MFF = Mountain Front Fault; ZFF = Zagros Foredeep Fault), the yellow lines are lineaments line. The emphasis is on seismotectonic investigations to identify fault activities and investigate earthquakes. Seismotectonic and geological investigations have shown four significant fault zones (Figure 5.10), each with the potential for seismic activity. The activity impressions of these fault zones and their related earthquake epicenters and seismic potential were studied. Figure (5.10): The image shows the mapped active faults in the Lurestan arc, and Focal mechanisms are colored according to centroid depth. All earthquakes are plotted at relocated epicenter locations from this study; black lines are faults; “master blind thrusts” are dashed (DEF = Dezful Embayment Fault; MFF = Mountain Front Fault; ZFF = Zagros Foredeep Fault), red lines are fold shape, and yellow line are lineaments line. Download 0.84 Mb. Share with your friends:
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