Morphometric and Erosion Characteristics of Zagros Folds in Kermanshah province
Document Type : Original Article
Authors
1
Department of Geography, Faculty of literature and human sciences, Razi University, Kermanshah, Iran
2
Associate Professor in Geography Department of Razi University-, Kermanshah, Iran
10.22034/gmpj.2024.461835.1506
Abstract
Introduction
Folds are geological structures formed by the bending or curving of the Earth's crust due to compressive stress after rock layers have been deposited. These structures rarely remain intact over time, as they are continuously reshaped by tectonic activity and erosion. Rivers, in particular, play a significant role in altering the roughness and form of these folds. Given the critical importance of understanding fold patterns in various geological systems, it is essential to analyze and describe the elements of fold styles as a core component of structural geology studies. Understanding the mechanisms behind folding, the conditions that perpetuate geomorphological changes, and how erosion impacts these structures highlights the significance of this research.
In the Zagros region, the relationship between erosion and tectonics remains unclear. Therefore, this study aims to explore this relationship by examining the morphometrics of anticlines and identifying indicators of river activity's impact on the erosion of folded structures in Kermanshah province. The folded Zagros zone in Kermanshah province was selected for this study due to its characteristic northwest-southeast orientation. In this direction, anticlines and synclines feature north-west and south-east plunges, often exposing the Asmari limestone formation.
Methodology
To achieve the research objectives, the study began by mapping the axes and extents of the anticlines in the study area using 1:100,000 geological maps. The boundaries of the waterway catchment areas on both sides of the anticline ridges were delineated using the Arc Hydro add-on in the ArcGIS environment. Each catchment area was then named and numbered for every anticline.
The slope of each catchment area was determined based on geological signs from the 1:100,000 maps and included in the descriptive table of each catchment layer. Following this, the morphometric parameters of the catchment areas were extracted and analyzed. The identified anticlines and their respective parameters were entered into Excel and SPSS for further statistical analysis.
Results and Discussion
1. Relationship Between Anticline Area and Erosion: Measurements of the anticlines in Kermanshah province revealed a total area of 6435 square kilometers for 20 anticlines. The smallest anticline covered 21 km², while the largest spanned 2868 km². The analysis indicated that larger anticlines have correspondingly larger catchment basins, suggesting that river erosion occurs in parallel. A paired T-test on the significance of the anticline areas (x̄ = 321 km²) and their eroded areas by catchment basins (x̄ = 297 km²) showed no significant difference, implying that the anticlines have uniformly reacted to erosion. The statistical analysis also revealed that there is no significant relationship between the total surface area of the anticlines and their drainage basins, indicating that the ratio of these areas can reflect differences in erosion levels. By calculating the percentage of the basin area relative to the total anticline area, a ratio was obtained showing the proportion of anticlines protected from erosion.
2. Drainage Patterns on Anticlines: The study identified 4847 catchment areas across 20 Zagros anticlines in Kermanshah. Out of this total, 2302 catchment areas are located on the western banks of anticlines, 2338 on the eastern banks, and 207 related to closes. Rivers have carved out 13443 kilometers of flow paths, with significant differences in river length between the western, eastern, and close ruz. The total length of rivers is 4556 km on the western banks, 3679 km on the eastern banks, and about 3679 km for closes. Statistical tests showed no significant difference between the lengths of ruz on either side of the ridges but highlighted a clear difference between ruz and closes. Closes have caused more significant destruction compared to ruz.
3. Drainage Indicators: Three main characteristics were used to investigate the drainage situation on anticlines: drainage density, river frequency, and drainage texture. Drainage density is calculated from the length of the river divided by the catchment area, providing an index of the degree of cutting in the anticlines. The study found that the average length of streams in the western ruz, eastern ruz, and closes is 2.9 km. This significant difference between closes and ruz can serve as a decision index for distinguishing them in satellite images. A statistical test of variance on the average index of stream length for the western, eastern, and close ruz confirmed no significant difference between ruz on both sides of ridges but a notable difference between ruz and closes. The index of the average length of the catchment area, considered in this research, can better indicate the slowness and depth of the rivers compared to the usual indicators of drainage density and texture.
Conclusion
1. All anticlines generally react to erosion in a similar manner, indicating that if the structural formation plays a role in erosion, it is not significant at the scale of the entire anticline. This uniformity suggests that structural influences on erosion are consistent across different anticlines.
2. There is no significant relationship between the total surface area of anticlines and the area of their drainage basins. This lack of correlation means that the ratio of these areas can illustrate the variation in erosion levels among different anticlines. Calculating the percentage of the basin area relative to the total anticline area provides a ratio indicating how much of the anticline is protected from erosion.
3. The study found no significant difference between the lengths of ruz on both sides of ridges. However, there is a clear distinction between ruz and closes, with closes causing significantly more destruction. This difference underscores the impact of river activity on the erosion of folded structures.
4. The index of the average length of the catchment area is a more effective measure of river activity's impact on erosion compared to traditional indicators like drainage density and texture. This index can help identify the slowness and depth of rivers more accurately, providing valuable insights for understanding erosion processes.
Folds are geological structures formed by the bending or curving of the Earth's crust due to compressive stress after rock layers have been deposited. These structures rarely remain intact over time, as they are continuously reshaped by tectonic activity and erosion. Rivers, in particular, play a significant role in altering the roughness and form of these folds. Given the critical importance of understanding fold patterns in various geological systems, it is essential to analyze and describe the elements of fold styles as a core component of structural geology studies. Understanding the mechanisms behind folding, the conditions that perpetuate geomorphological changes, and how erosion impacts these structures highlights the significance of this research.
In the Zagros region, the relationship between erosion and tectonics remains unclear. Therefore, this study aims to explore this relationship by examining the morphometrics of anticlines and identifying indicators of river activity's impact on the erosion of folded structures in Kermanshah province. The folded Zagros zone in Kermanshah province was selected for this study due to its characteristic northwest-southeast orientation. In this direction, anticlines and synclines feature north-west and south-east plunges, often exposing the Asmari limestone formation.
Methodology
To achieve the research objectives, the study began by mapping the axes and extents of the anticlines in the study area using 1:100,000 geological maps. The boundaries of the waterway catchment areas on both sides of the anticline ridges were delineated using the Arc Hydro add-on in the ArcGIS environment. Each catchment area was then named and numbered for every anticline.
The slope of each catchment area was determined based on geological signs from the 1:100,000 maps and included in the descriptive table of each catchment layer. Following this, the morphometric parameters of the catchment areas were extracted and analyzed. The identified anticlines and their respective parameters were entered into Excel and SPSS for further statistical analysis.
Results and Discussion
1. Relationship Between Anticline Area and Erosion: Measurements of the anticlines in Kermanshah province revealed a total area of 6435 square kilometers for 20 anticlines. The smallest anticline covered 21 km², while the largest spanned 2868 km². The analysis indicated that larger anticlines have correspondingly larger catchment basins, suggesting that river erosion occurs in parallel. A paired T-test on the significance of the anticline areas (x̄ = 321 km²) and their eroded areas by catchment basins (x̄ = 297 km²) showed no significant difference, implying that the anticlines have uniformly reacted to erosion. The statistical analysis also revealed that there is no significant relationship between the total surface area of the anticlines and their drainage basins, indicating that the ratio of these areas can reflect differences in erosion levels. By calculating the percentage of the basin area relative to the total anticline area, a ratio was obtained showing the proportion of anticlines protected from erosion.
2. Drainage Patterns on Anticlines: The study identified 4847 catchment areas across 20 Zagros anticlines in Kermanshah. Out of this total, 2302 catchment areas are located on the western banks of anticlines, 2338 on the eastern banks, and 207 related to closes. Rivers have carved out 13443 kilometers of flow paths, with significant differences in river length between the western, eastern, and close ruz. The total length of rivers is 4556 km on the western banks, 3679 km on the eastern banks, and about 3679 km for closes. Statistical tests showed no significant difference between the lengths of ruz on either side of the ridges but highlighted a clear difference between ruz and closes. Closes have caused more significant destruction compared to ruz.
3. Drainage Indicators: Three main characteristics were used to investigate the drainage situation on anticlines: drainage density, river frequency, and drainage texture. Drainage density is calculated from the length of the river divided by the catchment area, providing an index of the degree of cutting in the anticlines. The study found that the average length of streams in the western ruz, eastern ruz, and closes is 2.9 km. This significant difference between closes and ruz can serve as a decision index for distinguishing them in satellite images. A statistical test of variance on the average index of stream length for the western, eastern, and close ruz confirmed no significant difference between ruz on both sides of ridges but a notable difference between ruz and closes. The index of the average length of the catchment area, considered in this research, can better indicate the slowness and depth of the rivers compared to the usual indicators of drainage density and texture.
Conclusion
1. All anticlines generally react to erosion in a similar manner, indicating that if the structural formation plays a role in erosion, it is not significant at the scale of the entire anticline. This uniformity suggests that structural influences on erosion are consistent across different anticlines.
2. There is no significant relationship between the total surface area of anticlines and the area of their drainage basins. This lack of correlation means that the ratio of these areas can illustrate the variation in erosion levels among different anticlines. Calculating the percentage of the basin area relative to the total anticline area provides a ratio indicating how much of the anticline is protected from erosion.
3. The study found no significant difference between the lengths of ruz on both sides of ridges. However, there is a clear distinction between ruz and closes, with closes causing significantly more destruction. This difference underscores the impact of river activity on the erosion of folded structures.
4. The index of the average length of the catchment area is a more effective measure of river activity's impact on erosion compared to traditional indicators like drainage density and texture. This index can help identify the slowness and depth of rivers more accurately, providing valuable insights for understanding erosion processes.
Keywords
انصاریلاری، ا.، ثروتی، م.، رعیتی، ز.، ،1390، بررسی ژئومورفولوژی طاقدیس طاهونه، لارستان، مجلۀ جغرافیایی طبیعی، شمارۀ 4، صص86-73.
بهرامی، ش.، پرهیزگار، فاطمه.، 1395، تحلیل مورفومتری طاقدیسهای هوا و خشت و ارتباط آن با تکتونیکهای فعال در زاگرس فارس، فصلنامۀ علمی پژوهشی فضای جغرافیایی، شماره 56، صص 18-1.
جباری ایرج.، 1396، ژئومورفولوژی (ساختمان، فرآیند و زمینریختها)، چاپ اوّل، مؤسسۀ چاپ و انتشارات سمت، تهران.
علاییطالقانی، محمود.، 1394، ژئومورفولوژی ایران، چاپ اوّل، مؤسسۀ چاپ و انتشارات قومس، تهران.
قنواتی، ع.، صفاری، ا.، حقشنای، علی.، 1400، بررسی شاخصهای مورفومتری تاقدیسهای عسلویه، وراوی و کنگان در زاگرس فارس و ارتباط آنها با فعالیتهای تکتونیکی، نشریۀ تحلیل فضایی مخاطرات محیطی، شماره3، صص73-92.
یمانی، م.، مرادیپور، ف.، مرادی، ا.، مرادیپور، س.، 1399، برآورد دامنۀ فعالیت زمینساختی تاقدیس خویز ازطریق معیارهای مورفومتری، زاگرس خوزستان، مجلۀ آمایش جغرافیایی فضا، سال دهم، شماره37، صص14-1.
-Altin, T.B., Altin, B.N. (2022). "Development and morphometry of drainage network in Volcanic terrain, Central Anatolia, Turkey. Geomorphology, 125,485-503.
-Azor, A., keller, E.A. (2002). in dicators of active fold growth: Soth Mountain- Oak Ridge anticline, Ventura basin, southern California”, Geological society of America bulletin, 114(6), 745-753.
-Berberian,M. (1994). Mster blind thrust faults hidden under the Zagros folds:active basement tectonics and surface morphotectonics,Tectonophysics, 241, 193-224.
-Blanc.J.P,Allen.M.B,Tnger.S,hassani.h. (2003). structural styles in the Zagros simple folded zone.Iran,Journal of the geological society London, 160, 401-412.
-Bretis, B., Bartl, N., Grasemann, B. . (2011). Lateral fold growth and linkage in the Zagros fold and thrust belt . Kurdistan, NE Iraq. , basin Research, 23, 615-630.
-Burberri.C.M,Cosgrove.J,W,Guoliu.j. (2010). Study of fold characteristics and deformation style using the evolution of the land surface Zagros simply folded belt,Iran,papers in the Earth Atmospheric scienes,295,139-154.
-Burberry,C,M.Cosgrove,J.Guoliu,J. (2007). Stream network characteristics used to infer the distribution of fold types in the Zagros simply fold belt,Iran, Journal of maps student edition, 32-45.
-Chandrashekara,H., Lokesh, K. V., Sameenam, M., Roopa, J., Ranganna, G.) 2015). GIS-Based morphometric Analysis of Two Reservoir Catchments of Arkarati River, Ramanagaram District, Karnatak, INTERNATIONAL CONFERNCE ON WATER RESOURCES, COASTAL AND OCEAN ENGINEERING (ICWRCOE 2015), doi: 10.1016/j.aqpro.2015.02.175.
-Ciccacci, S., Fredi, p., Lupiapalmieri, E., Pugliese,F. (1986). Indirect evaluation of erosion entity in drainage basins through geomorphic,climatic and hydrological parameters. Inter national geomorpholog(2), 33-48.
-Delcaillau, B., Carozza, J.M.,Laville, E. (2006). "Recent fold growth and dranige development”, the Janauri and Chandigarh anticlines in the siwalik foothills, northwest India, Geomorphology, 76, 241-256.
.Guarnieri, P and Pirrotta, C. (2008). "the response of drainage basins to the late Quaterary tectonic in the Sicilian side of the Messina Strait (NE Sicily)". Geomorphology, 95:260-273
-Jackson, J., Van Dissen, R., Berryaman,K. (1998). "Tilting of active folds and faults in the Mana watu region. New Zeal and evidence from surface dvaionage patterns” new zeal and Jornal of Geology and Geophysics, 41,377-385.
-Keller, E. A. Pinter,N. (2001). "Tectonic process analysis in Zagros Mountain with the aid of druianage networks and topography maps dated,(1950-2001) in GIS", Arabian Journal of Geoscience,4:171-180.
-Ramsey, L.A., Walker,R.T., Jakson,j. (2008)."Fold evolution and drainage development in the Zagros mountains of the Fars province" SE Iran, basin Researche, 20, 23-48.
-Ribolin, A. Spagnolo, M. (2007). Drainage density, slope angle, and relative bas in position in Japan ese bar land from high- resolute in DE Ms. 159-173.
-Stanley. A. Schumm, F Dumont &John, M. Holbrook. 2000. Adive.Toctonics and alluvial rivers. Comb ridge university press.
-Sung,O.,Chen, Y.C. (2004)."Geomorphic evidence and kinematic model for quaternaty transfer faulting of the pakuashan anticline, central Taiwan", Journal of Asian Earth Sciences, 24,389-404.
-Talling, P and Sowter, M.J. (1999). "Dvainage density on progressively tilted surfaces with different gradients, wheeler Ridge, Calieorning”, Earth surface processes and land from, 24, 809-824.
Yue-Gau-chen, Jih- Hao Hing, Kuang- YinLai, Yu- Nung. Lin, Tarka WilcoX. (2007). River Terrace development in response to folding above active wedge thrusts in Houli Central Taiwan. Journal of Aisian Earth Science, 31, 240-250.
