Iraqi National Journal of Earth Sciences

Abstract

Analysis of brittle failure structures carried out throughout a traverse across Azmur Anticline, NE Iraq. This includes widespread joints, mesofaults, planar and enechelon vein arrays and pressure solution surfaces ( stylolite seams ). The aim of this work is for unraveling the tectonic history and detecting tectonic episodes responded for the initiation and modification of such brittle failure structures.Field observations and analysis revealed two subsequent compressive phases. The oldest trending ENE-WSW is normal to the Azmur fold axis, while the second is parallel to it. These directions ascertained by paleostress tensors deduced from slip analysis of striated mesofaults. Reorientation of stress regime from first compressive phase to the second has been attributed to the progressive oblique collision of Arabian and Eurasian plates. Furthermore, a final stretching phase in NE-SW direction had been deduced. This extensional phase which ought to the uplifting stage of fold structure is responsible for bedding parallel stylolite seams with vertical peaks, and normal slip faulting in the studied area.