Exhumation Style of the Chapedony Core Complex (Central Iran): Insights from Kinematic Vorticity Analysis

Abstract

Kinematic characteristics of mylonite rocks in the footwall of the Chapedony detachment shear zone was investigated to highlight the exhumation style of the Chapedony Metamorphic Core Complex, Central Iran. The mean kinematic vorticity value (Wm) was evaluated applying the rigid grain net technique on the mylonitic rocks of the metamorphic core complex. The results revealed Wm values ranged from 0.61 to 0.89 suggesting a general shear deformation with 23‒57% pure shear and 43‒77% simple shear, respectively. As a consequence of these conditions, the metamorphic rocks of the core complex was subjected to ductile thinning (0.11‒0.38 stretching) during the crustal extension. Mismatch of vorticity and strain values highlights that pure shear was dominant at the early stage of the core complex formation while simple shear becomes increasingly important towards the last stages of exhumation due to progressively unloading during uplift.