Petrography and Geochemistry of the Baska Piwaza Ore Mineralization, Halgurd Mountain, Iraqi Kurdistan Region: Insights on the Genesis

Abstract

This paper is the first attempt to study the mineralogical and geochemical features of mineralization hosted within the volcanic rocks of the Baska Piwaza section, at Halgurd Mountain, which is the highest mountain in Kurdistan and the whole of Iraq. The host lithologies in the studied section represent mostly volcanic rocks (basalts to andesites), and secondary sedimentary lithologies, such as radiolarian chert. There are two main stages of oxide and sulfide mineralization that can be recognized under three-time epochs which are early, middle and late stages that caused the formation of oxide and sulfides ore minerals. The most dominant oxide mineral is hematite, with minor contribution of magnetite, goethite, and rutile. In terms of sulfides, pyrite is the predominant mineral phase with secondary contribution of chalcopyrite. The petrographic study and XRD data of the host volcanic rocks reveal that the most abundant minerals are plagioclase, K-feldspar, pyroxene, and amphibole, while the secondary minerals are quartz, calcite, clinochlore, sericite, prehnite, pumpellyite, and muscovite. Additionally, the radiolarian chert is comprised by quartz, hematite, calcite, ankerite, clay minerals, and apatite which is characterized by low silica content and high iron oxide. Low concentration of TiO2 ,and Fe2O3 are suggesting the quartz vein occurred with the volcanic rocks are formed due to low hydrothermal fluid. Field observation, petrographical and geochemical data indicate that the rocks of the Baska Piwaza section are influenced by hydrothermal alteration, due to the high value of Loss On Ignition (LOI) and the high ratio of alkalis (Na2O+K2O). Moreover, evidences of chloritization and sericitization of the mafic minerals, and feldspar minerals respectively support the hydrothermal impact.