Extended Abstract

Introduction

Recent geomorphological studies utilize morphometric analyses as an efficient method for identifying geological structures and tectonic patterns. The study and identification of areas with tectonic activity is of particular importance, because these areas reflect the movements of the youngest periods, especially the Quaternary period and especially the Holocene and the present. Indeed, tectonic geomorphology analyzes the relationship between tectonic forces and geomorphic processes affecting the formation of landforms and geomorphological landscapes in areas with active deformation. Therefore, topographic analyses are considered an effective tool for measuring landscape forms, because the impact of tectonic activities on the topography of the earth is widely evident. This study investigates the relative tectonic activity in the Ahoran-Lashar region of the Makran Mountain Belt (MMB), southern Sistan and Baluchestan province.



Materials and Methods

Eight geomorphic indices (SMF, VF, AF, FMF, EU, FD, BS, T) were calculated and integrated into the Relative Tectonic Activity Index (IAT) introduced by El Hamdouni et al. (2008). In addition, topographic and geological maps, a 12.5-meter DEM, and Landsat and Sentinel satellite imagery were integrated within a GIS environment and validated with field evidence.





Results and Discussion

The SMF index exhibits a relatively uniform spectrum, ranging from 0.91 to 1.20. The highest value (Smf = 1.20) occurs in front 4 in the south, while the lowest (Smf = 0.91) is in front 5 in the west. The mean index value of 1.07 (Table 2) indicates very high to high tectonic activity, classifying the area as class 1 activity. Valley 23 (Vf=0.05), located within the Kajou fault, exhibited the lowest value, indicating high activity. Conversely, valley 28's value of 3.81 was the highest, suggesting relative inactivity (Table 3). The average index value of 0.42 classifies the studied region as class 1 activity (very high). The values of the Fmf index varied between 118.41 (related to front number 14) and 356 (related to front number 2). Also, the average of this index in the studied area was found to be 236.03 (Table 4). The high percentage of these levels indicates the high tectonic activity in this area of the Makran mountain belt. In general, the results of the Fd index calculations show low numerical values and a relatively uniform spectrum with a low range of variability. In other words, the lowest and highest calculated values were about 0.18 for front number 7 and 0.41 for front number 2, respectively. Also, the total average for the region was obtained as 0.29 (Table 5). The calculated values for the Eu index show a spectrum with a moderate variability range; its values ranged from 0.41 to 0.72, and its total average in the region was also measured to be 0.56 (Table 6). These values indicate a relatively moderate to high percentage of uncut sections of the mountain fronts of the study area, which in most cases are externally manifested as continuous escarpments and sometimes as fault and straight cliffs (Figure 7). The highest Af index was measured in basin number 16 (Af=9.67) in the northern part of the region and the lowest in basin number 18 (Af=3.26) in the southern part of the region (Table 7). The results show that the watersheds of the region are divided into three classes based on the degree of tilt (Figure 5 and Figure 8). In general, the results of the Bs index show that the studied basins are in categories 2 and 3 of tectonic activity. More precisely, the lowest and highest values calculated for this index belong to basin number 18 with a numerical value of 1.23 and basin number 1 with a numerical value of 2.29, respectively, which indicates relatively low to moderate tectonic activity (Table 8). Analyses conducted using these indices provided a very clear view of the status of tectonic activities in the region. In general, the results obtained show that the highest level of activity is in the southwestern, southeastern, northwestern, and finally northeastern parts of the region, respectively. Also, the calculated indices suggest moderate to high tectonic activity in the region. Integrating measured indices values into the IAT unit index yielded a value of 1.7, classifying the study area as class 2, indicating high tectonic activity. Finally, the findings obtained from the indices were matched and verified with the existing geomorphological evidence in the region, such as linear and straight mountain fronts, deep and V-shaped valleys, greater elongation and tilting of basins, a high proportion of triangular facets, a low percentage dissected mountain fronts and a high percentage undissected escarpments.



Conclusion

This study assesses the relative tectonic activity of the Ahoran-Lashar region situated in the Makran mountain belt using geomorphic indicators. Mountain front sinuosity, triangular facets, stream displacement, V-shaped valleys, and the absence of foothills suggest active tectonics in the region. These indices offer a valuable relative classification for preliminary tectonic assessments. Geomorphic indices and field evidence indicate that the study area is tectonically active. Specifically, the IAT index classified the area as class two with high tectonic status, suggesting ongoing neotectonic activity consistent with other indices and field observations in the region.