Document Type : Original Research Paper
Authors
1 Ph.D. Student, Department of Geology, Tarbiat Modares University, Tehran, Iran
2 Associate Professor, Department of Geology, Tarbiat Modares University, Tehran, Iran
3 Assistant Professor, School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran
Abstract
Mechanical characterizations of sedimentary cover, especially presence of ductile rock units is a major controlling parameter on deformation style within fold and thrust belts. Interpretation of seismic profiles as well as scaled analogue modeling allows us to determine the influence of ductile levels on structural style in the Central Zagros folded belt. Seismic interpretation indicates that the Miocene Gachsaran Formation forms a major median detachment level decoupling fold geometry in surface structures from Pre-Miocene units below it. In addition, the Infra-Cambrian Hormoz salt or equivalents decouple the folded sedimentary cover from basement. To evaluate the significance of multiple detachment levels, a scaled analogue model was set. Two layers of silicon putty, with thicknesses equal to 15% of total cover thickness, were placed at the base and in the middle of sedimentary cover. The rest of the sedimentary cover was simulated using dry loose sand. The result of modeling supports seismic interpretation of the Central Zagros proposing that thick middle detachment layer totally decouples structural style at surface from depth. However, the open synclines with long wavelength and low angle thrusting are developed at surficial levels, and duplex thrust systems are formed between two detachment levels. Therefore, the role of ductile detachment levels should be obtained before exploring deep hydrocarbon targets in the Zagros fold belt.
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