Shear Zone-Hosted Base Metal Mineralization near Abraha Weatsebaha-Adidesta and Hawzein, Tigray Region, Northern Ethiopia

Low-grade basement rocks of Neoproterozoic age with well developed shear zones and posttectonic granitic intrusives from Hawzien area of northern Ethiopia were studied for field characteristics, mineralogy, textures, alteration assemblages and geochemistry to explore their potential for base metal mineralization. The basement rocks includes metavolcanic (mafic to felsic), metavolcaniclastic and metasedimentary rocks. The intrusive post-tectonic granitoids mark the end of Proterozoic. Field observation and petrographic data indicate the presence of NS, NE-SW trending shear zones; hydrothermal quartz (±calcite) veins of different generations; malachite stains; alterations like chloritisation, kaolinization, epidotization, sericitization; and presence of base metal sulfides in association with quartz and calcite veins. Geochemistry of surface and drill core samples indicate enrichment of zinc in shear zones with low concentrations of copper, lead, gold, arsenic and silver. Zn-rich base metal mineralization with Pb-Cu-Fe (±Ag-As-Au) is related to D2 deformation. Barite veins are although common, conspicuously occurring in E-W trending veins. Post-tectonic granitoids are facilitating the hydrothermal activity and the source rock compositions controlling the nature of the mineralization. A paragenetic scheme is suggested on the basis of texture, mineral association, alteration and deformation.