Petrology, Minerals chemistry and Geochemical relationships of the Sheared Gabbro Rocks in Alanah (Beesha) area within Erbil Governorate, NE Iraq

Abstract

The current research is seeking to identify the petrography, mineralogy and geochemical relationships of Gabbro rocks in Besha area within Erbil Governorate, at the Unstable Shelf in Imbricate Zone. This study aims to determine the origin of the gabbroic rocks and their geochemical relationships. The basic sheared gabbro rocks are exceptional in the studied area at Alanah (Beesha) in samples (B1, B2, B3, B6, and B8). The sheared gabbroic rocks contain fine to very fine crystals of plagioclase which is presenting as euhedral to subhedral tabular crystals and anhedral grains that cumulate and fractured by shearing stress that can be concentrically zoned as well as processing polysynthetic twins. The gabbroic rocks in the area of study are characterized by moderate to high ranges of the loss on ignition. These variation values are a crude measuring of the rock alteration degree. Accordingly, all gabbro rocks types have been affected by the variable alteration degree. These gabbroic rocks exhibiting the tholeiitic geochemical features, with characterized by good trend of sub-alkaline tholeiitic in the total alkalis-silica and AFM relationships with the medium-K tholeiitic. Generally, the most distinctive properties exhibiting by using spider diagrams of the gabbro rocks in the studied area are selected enrichment of the certain elements such as Sr, Ba and U, addition to relatively lack of enrichment of Zr, Y and Hf. These geochemical patterns and the variation of the HFSEs are exhibiting by the tholeiite rocks are characterization of the supra subduction Zone. In Addition to all analyzing opaque minerals in the sheared gabbro rocks of the area of study are representing alumina magnetite and secondary magnetite.