تحلیلِ تکاملِ چشم‌اندازهای ژئومورفیکِ منشور بَراَفزایشی مکران، جنوب‌خاوری ایران

Extended Abstract

Introduction

Earth's surface landforms and geomorphological landscapes are constantly evolving. Geomorphic systems are complex, leading to uncertainties in our understanding of their state. Thus, the ability to measure variables is crucial for geomorphologists. Therefore, the main goal of scientific explanation in the science of geomorphology is the ability to measure the processes and environmental factors that affect the evolution of the Earth's landscapes and landforms. As Mansouri et al. (1401) noted, quantitative methods in geomorphology are important because they offer tools to accurately and efficiently quantify interactions between landforms and related processes, enabling more effective description and interpretation. Tectonic geomorphology studies the interplay between tectonic forces and surface processes that sculpt Earth's landscapes, particularly in active deformation zones. Quantitative topographic analysis is valuable for measuring landforms and geomorphological landscapes because tectonic activity significantly shapes the Earth's topography. In earth sciences, including geomorphology, digital elevation models are commonly used to extract and evaluate topographic swath profiles, providing insights into surface conditions and roughness. Geoscientists commonly employ topographic and drainage network analyses in tectonic geomorphology (e.g., Pérez-Peña et al., 2009a; 2009b; 2010; Kirby and Whipple, 2012; Giaconia et al., 2012; Royden and Perron, 2013; Willet et al., 2014; Pérez-Peña et al., 2017). Specifically, topographic swath profiles are used to analyze these patterns, revealing landscape elements and tectonic influences (e.g., Molin et al., 2004; 2012; Andreani et al., 2014; Scotti et al., 2014; Azañon et al., 2015). Swath profiles analysis is most widely used in tectonic geomorphology. Numerical evaluation of tectonic uplift or subsidence, detection of fault location, explanation of river capture and antecedent valley formation, as well as testing of geophysical models, are among the most common applications. The present-day great availability of high-resolution Digital Elevation Models has improved tectonic geomorphology analysis in its methodological aspects and geological meaning. Today, it has been proven that swath profile analysis has proved to be useful in the study of large orogens to evaluate the effects of vertical surface movements, as well as in the investigation of fluvially or glacially sculpted topography. One of the main applications of topographic swath profiles is morphological and morphotectonic analysis of various landscapes on the Earth's surface to explore the short and long-term landscape response to tectonic activity and climate changes. Most of the morphometric analyses are conducted in GIS software, which has become a standard tool for analyzing drainage network metrics.



Materials and Methods

To investigate the long-term evolution of the landscape within the Iranian part of the Makran Accretionary Prism, with a particular focus on the interaction between active tectonic processes and the erosional impact of deep river incision, we employed the SwathProfiler plugin. This methodology allowed us to generate topographic swath profiles, providing a detailed representation of the landscape's morphology. A key advantage of this approach, as originally described by Pérez-Peña et al. (2017), lies in its streamlined and automated execution. The entire workflow is designed to be readily implemented using digital elevation models (DEMs) data within the widely used ArcGIS software environment, ensuring efficient data processing and analysis. The ease of use and automation significantly reduce the time and effort required for generating swath profiles, making it a valuable tool for large-scale landscape studies. Furthermore, to complement the topographic analysis, we integrated both topographic and geological datasets. Topographic information was extracted from topographic maps at scales of 1:250,000 and 1:50,000, providing a range of spatial resolutions for detailed and regional analysis. Geological data, crucial for understanding the underlying structural controls on landscape evolution, were derived from geological maps at scales of 1:100,000 and 1:250,000. The integration of these diverse datasets, encompassing topographic and geological information at multiple scales, allowed for a comprehensive assessment of the factors influencing the long-term landscape development of the Makran Accretionary Prism. The combination of the SwathProfiler plugin's efficient processing capabilities with the availability of detailed topographic and geological data enabled a robust and insightful investigation into the complex interplay of tectonic and fluvial processes shaping this dynamic region.

The SwathProfiler minimizes the time and the calculation process to extract swath and longitudinal river profiles. They also allow the extraction of key information from profiles that may help in their interpretation and analysis. Swath profiles can be examined statistically to extract maximum, minimum, and mean topographic elevation for each transect. Mean elevation is a good approximation to the general topographic trend of the landscape within the swath profile band, whereas maximum and minimum elevation can inform about landscape variations in the direction perpendicular to the swath profile. Moreover, other parameters as local relief (maximum elevation - minimum elevation) or quartile (Q1 - Q3), can also describe topographic variations along the swath. Generally, stable areas as basins or plateaus with low-to-moderate incision, will yield low values of local relief and swath profiles where all lines will merge. Conversely, high local relief and wider variations of swath profiles will be characteristics of mountain ranges or highly dissected landscapes exposed to high incision and/or uplifting (Pérez-Peña et al., 2017).



Results and Discussion

In general, the longitudinal topographic profiles show remarkable features. Generally, the results indicate substantial variations in both longitudinal and transverse profiles, with a significant degree of oscillation observed in their respective values (maximum elevation (0-2200 m), minimum (0-1500), mean (0-1680), Q1 (0-1610), Q3 (0-1850), local relief (0-1550) and THi* (0-0.8)). All longitudinal profiles have recorded a very high percentage of relief, which indicates the presence of a rugged mountainous landscape along the main direction of the Makran belt. Additionally, by carefully examining these profiles, we can observe a type of topographic asymmetry in the path of the profiles, except for the diagram related to the inner Makran, which somehow displays a state of relative topographic symmetry. Overall, a general examination of the longitudinal profiles shows that in the outer and inner Makran subzones the topographic situation is relatively compact; however, in northern and coastal Makran, the level of compression and density of relief is reduced in favor of the expansion of low and low-lying surfaces (corresponding to the unit of wide valleys, plains). However, the northern Makran highlands still have a higher relative density than coastal Makran. On the other hand, the transverse topographic profiles also show very interesting features and differences in the topographic situation of the region. Generally, all profiles perpendicular to Makran are asymmetrical. The main reason for their asymmetry is the effect of the action of the main faults and thrusts in the region (including: Chahkhan, Ghasr-e Ghand, Bashagard, and Bampour thrusts). Therefore, as these profiles show, it is easy to observe the Makran subzones and their boundaries. Overall, the findings show that all longitudinal and transverse profiles recorded high changes in their values. In other words, in most profiles, the local relief curve has high variability and values. Also, the values of the enhanced transverse Hypsometric Integral index (THi*) show high variations. Thus, the highest and lowest THi* values were recorded in the North Makran longitudinal profile (affected by the Minab Thrust) and Outer Makran longitudinal profile, respectively, as well as in transverse profiles 1, 2, and 4. In addition, in significant parts of the longitudinal and transverse profiles, it was observed that the profile of the mean elevation moved away from the minimum and, along with the third quartile curve, approached the maximum. Overall, the findings of this study demonstrated that higher values (close to 1) of the THi* index, along with the mean elevation curve and the third quartile closing the maximum in many areas, indicate the existence of a young landscape and a transient state of adjustment to higher uplift rates.

Overall, the results indicate a strong correlation between the first quartile parameter and both the mean and minimum elevation, with a confidence level of 99%. Pearson's correlation coefficient (r) values for the first quartile were 0.997 with mean elevation and 0.993 with minimum elevation. On the other hand, the results also demonstrate a robust correlation between the mean and minimum height parameters (Table 4). Positive values between these parameters indicate a positive and additive effect between them. Furthermore, strong relationships and correlations are evident between the Q3 and the mean, the Q1 and Q3, the Q3 and the maximum elevation, and the Q3 and the minimum elevation, all at a 95% confidence interval (Table 5).



Conclusion

The topographic analysis conducted in this study, characterized by its rapid execution, has demonstrated the considerable potential for employing topographic swath profiles. This method proves both useful and practical when examining the relief characteristics of mountainous regions, especially when such analyses are performed over a regional extent. The study underscores the value of topographic swath profiles as an effective tool for understanding and quantifying the complex surface variations inherent in mountainous landscapes. By utilizing this approach, researchers and practitioners can gain valuable insights into the geomorphological features and processes shaping these areas. Therefore, the application of topographic swath profiles offers a valuable and efficient means of analyzing the relief of mountainous terrains at a regional scale, highlighting its applicability in various geomorphological studies and environmental assessments. The SwathProfiler extension within the ArcGIS software provides a streamlined approach to conducting sophisticated topographic analyses. This tool is designed to facilitate rapid and efficient processing, making it particularly useful for geomorphological and morphotectonic investigations that cover extensive geographic areas. Specifically, its capabilities are optimized for landscape studies conducted at a regional scale, allowing researchers and analysts to easily perform advanced analyses of topographic data. By employing the SwathProfiler extension, ArcGIS users can readily extract valuable insights from topographic information, leading to a more comprehensive understanding of landscape evolution and tectonic processes across broad regions. The creation and subsequent analysis of topographic swath profiles within the Iranian section of the Makran prism proved valuable in discerning and elucidating regional topographic characteristics. This process, utilizing a digital elevation model as its primary data source, facilitated the consideration of both internal tectonic processes and external erosional influences that collectively shape the landscape. By employing topographic swath profiles, we were able to effectively recognize and interpret the dominant topographic patterns present in the region. The extraction of these profiles specifically allowed for a more detailed examination of the interplay between the forces of tectonic uplift and deformation, which originate from within the Earth, and the surficial processes of erosion, driven by external factors such as climate and weathering. This approach offers a comprehensive understanding of the factors responsible for the observed topographic features in this tectonically active area.