University of Sistan and Baluchestan Journal of Natural Environmental Hazards 2676-4377 Articles in Press 2025 12 25 Assessment of Neotectonic Activity in the Zanjan-Rud Basin Using Fibonacci Golden Ratios Assessment of Neotectonic Activity in the Zanjan-Rud Basin Using Fibonacci Golden Ratios 1 1 9627 10.22111/jneh.2025.53330.2139 FA Gholam Hassan Jafari Associate Professor, Department of Geography, University of Yasouj, Yasouj, Iran Journal Article 2025 09 24 The Zanjan-Rud Basin, located in northwestern Iran, is a tectonically active region influenced by major faults such as the Sultaneih and Northern Zanjan faults. This study aimed to evaluate the morphotectonic status of the basin using digital elevation model (DEM) data and the application of Fibonacci golden ratios (0.236, 0.382, 0.5, 0.618, 0.764, and 1) for slope classification. The results revealed that over 84.6% of the basin lies within a slope range of 7–23%, indicating generally weak to moderate tectonic activity. However, areas with slopes exceeding 76% (Fibonacci ratio 0.764) and above 76% (ratio 1) were identified along structural lineaments, particularly near the Sultaneih and Northern Zanjan faults. These zones exhibit steep topography, deep valleys, and abrupt changes in drainage patterns, suggesting potential neotectonic influence. Lithological resistance was also found to play a significant role in shaping high-slope features, especially in areas dominated by andesitic and metamorphic rocks. Comparative analysis with previous studies indicates that while some geomorphic features may be attributed to erosional processes and base-level adjustments during the Quaternary, others reflect recent tectonic activity. The use of Fibonacci ratios proved effective in identifying critical thresholds in topographic variation, offering a novel quantitative approach for neotectonic assessments in similar geological settings. The Zanjan-Rud Basin, located in northwestern Iran, is a tectonically active region influenced by major faults such as the Sultaneih and Northern Zanjan faults. This study aimed to evaluate the morphotectonic status of the basin using digital elevation model (DEM) data and the application of Fibonacci golden ratios (0.236, 0.382, 0.5, 0.618, 0.764, and 1) for slope classification. The results revealed that over 84.6% of the basin lies within a slope range of 7–23%, indicating generally weak to moderate tectonic activity. However, areas with slopes exceeding 76% (Fibonacci ratio 0.764) and above 76% (ratio 1) were identified along structural lineaments, particularly near the Sultaneih and Northern Zanjan faults. These zones exhibit steep topography, deep valleys, and abrupt changes in drainage patterns, suggesting potential neotectonic influence. Lithological resistance was also found to play a significant role in shaping high-slope features, especially in areas dominated by andesitic and metamorphic rocks. Comparative analysis with previous studies indicates that while some geomorphic features may be attributed to erosional processes and base-level adjustments during the Quaternary, others reflect recent tectonic activity. The use of Fibonacci ratios proved effective in identifying critical thresholds in topographic variation, offering a novel quantitative approach for neotectonic assessments in similar geological settings. https://jneh.usb.ac.ir/article_9627_2101fe22f45ff059751fda1e436826aa.pdf