Extrapolation Paleostress Orientations Deduced from Joints Analyses at Spi Rais and West Part of Chai Gara Anticlines, Duhok Area, Kurdistan Region, Iraq

• Published in: Iraqi geological journal 2023-10, Vol.56 (2D), p.324-345
• Main Authors: Abdullah, Nazar, Al Sumaidaie, Mahmood, Aljumaily, Ibrahim
• Format: Article
• Language: English
• ISSN: 2414-6064; 2663-8754
• DOI: 10.46717/igj.56.2D.24ms-2023-10-30

Spi Rais anticline (East part of major Bekhair anticline) and western part of Chia Gara anticline were chosen to study joint paths. They are located within the highly folded zone of the western zagros fold and thrust belt, Iraqi segment. These anticlines arranged in an en-echelon pattern and they expose rocks range in age from Late Cretaceous to Late Miocene. The Late Cretaceous (Campanian – Maastrichtian) succession represented by Bekhme and Shiranish Formations. The lithologies of these rocks are competent and consist of limestone, dolomitic limestone and marly limestone whichare favorable to joint development. Different types of joints were developed in such rocks due to stresses resulted from collision between Arabian and Eurasian (Turkish and Iranian) plates. The joint sets and systems are the most abundant fractures in the rocks of the study area. The chronological relationships of the joints refer that the area had witnessed multiple tectonic pulses in the form of compressional and extensional stresses. The stereonet and the Win – Tensor programs were used to plot the attitudes of joints and deduce their paleostresss orientations. Furthermore, the orientations of deduced paleostresses were plotted onto geological map of investigated area and simulated as paleo trajectories as well. The deduced paleostress direction responsible for folding in traverse 1 was (356° - 195°), in traverse 2 (330° - 168°) and in traverse 3 (353°- 163°).