Characterization of Base Metal Mineralization from Tigray Region, Ethiopia

Abstract

A comprehensive investigation was conducted on the Neoproterozoic basement rocks in the Hawzien region of northern Ethiopia. These rocks exhibit characteristics of low-grade and are accompanied by well-developed shear zones and post-tectonic granitic intrusions. The study aimed to analyse the field characteristics, mineralogy, textures, alteration assemblages, and geochemistry of these rocks to assess their potential for base metal mineralization. The basement rocks encompass a variety of metavolcanic (ranging from mafic to felsic), metavolcaniclastic, and metasedimentary rocks. The Proterozoic era is characterised by the presence of intrusive post-tectonic granitoids. Based on field observations and petrographic data, it is evident that there are shear zones trending in the NS and NE-SW directions. Additionally, there are hydrothermal quartz (calcite) veins of multiple generations, malachite stains, and various alteration phenomena including chloritization, kaolinization, epidotization, and sericitization. Furthermore, base metal sulphides are found in conjunction with quartz and calcite veins. Despite their widespread occurrence, barite veins are predominantly observed in veins that tend in an east-west direction. The mineralization characteristics are influenced by the compositions of the source rocks, whereas hydrothermal activity is facilitated by post-tectonic granitoids. The proposal of a paragenetic framework involves the consideration of texture, mineral association, alteration, and deformation.