Growth history and linkage pattern of fault-related folds deciphered from geomorphic analysis: A case study from the Dalan Anticline, Zagros Mountains, SW Iran

Abstract

Linkage pattern and growth history of fault-related folds have important implications for petroleum exploration. This study evaluates the lateral growth and fold segmentation in the Dalan Anticline as a NW-SE trending hydrocarbon trap manifested as a fault-related fold within the Zagros Fold-Thrust Belt, SW Iran via tectonic geomorphology analyses. Several qualitative and quantitative geomorphic evidence including wind and water gaps, drainage network, deflected drainage, drainage density, basin shape, fold front sinuosity, degree of incision in the drainage basin outlet, stream-length gradient, asymmetry factor and hypsometric integral and related curves were used to investigate the lateral propagation and linkage pattern in the fold. Systematic variation of these parameter's value highlighted the three younger parts of the fold with smaller, elongated and crescent-shaped basins, concave hypsometric curves. This evidence reveals the presence of two independent fold segments propagating both in northwest and southeast directions, respectively. The development and evolution of these segments might led to the spatial and temporal differences in the geometry and activity intensity of the fold. This study emphasizes the importance of understanding the growth history of fault-related folds in order to understand hydrocarbon migration and accumulation in fold and thrust belts.