Analysis and Comparison of Paleostress Variations Using Structural Pattern and Slip Data Inversion Methods in the Southern Part of the East Iranian Tectonic Belt

Document Type : Original Article

Authors

1 PhD Student in Tectonics, Faculty of Sciences, Department of Geology, Birjand University, Birjand, Iran

2 Department of Geology University of Birjand

3 Department of geology- faculty of science - university of Birjand - Iran

4 Department of Geology, Faculty of Sciences, University of Sistan and Baluchestan, Zahedan, Iran

Abstract

The study area is located in southeastern Iran, north of Iranshahr and south of Khash, and from a geological perspective, it lies in the southern part of the mountainous region of eastern Iran. Indicators of this area include diverse geological structures (extensional, compressional, and shear), which reflect a complex tectonic history. For a better understanding of the deformation processes, stress calculations and reconstructions can be utilized, and this study employs two methods: inversion of fault data and analysis of structural patterns. To calculate stress axes at different times, field surveys were conducted, including fault planes, slip surfaces, and hinge surfaces of folds in the area. The results obtained are almost identical. Analyzing the kinematic data of the faults and calculating stress tensors at various times reveals three stages of change in the original compressive position (σ1) during the Cretaceous (N10°±10°), Eocene (N60°±25°), and Miocene (N6°±15°). Additionally, examining the shortening direction of the folds shows three stages of shortening with trends of 1- north, 2- east, 3- northeast. Therefore, it can be stated that the first-generation folds are the oldest deformation events with an east-west axis, while the second and third-generation folds also occur in the second deformation event coinciding with the closure of the Sistan basin in the Paleogene, and the conjugate fractures that have caused the displacement of other geological structures were also formed during the Neogene.

Keywords

Journal of Tectonics
Volume 7, Issue 26
September 2023

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