Kamoreib Metavolcanic Rocks: A key to understand the Tectonic Evolution of the Southern Hamisana Shear Zone, Red Sea Hills, NE Sudan

Abstract

The Kamoreib area lies in the southern part of the Hamisana Shear Zone (HSZ), within the Nubian Shield as a transitional area between Gabeit and Gabgaba terrains. The tectonic setting of this area is relatively poorly understood. Therefore, the present investigation is concerned mainly with the geological and tectonic setting of the metavolcanic group at Kamoreib area as a key to the recognition and understanding of the tectonic setting of the southern Hamisana area through petrographic and geochemical analysis. Detailed geological mapping based on interpretation of enhanced satellite image, field observation and petrographic investigations revealed that the mapped area is built up of metavolcanic assemblage ranging from basic to acidic in composition. The metavolcanics include porphyritic dacite, amygdaloidal andesite, andesite, rhyolite and basalt, intercalated with tuffaceous materials. These rocks are highly sheared, hydrothermally altered and regionally metamorphosed to greenschist facies. Petrographic and geochemical analysis revealed that the metavolcanics represent a mature island arc environment, which is characterized by calcalkaline geochemical affinity. The outcome of the present investigations revealed that the geographic distribution of the metavolcanics supported by the geochemical analysis present a perspective for constraining subduction polarity of the Kamoreib volcanic arc that were formed over a northwesterly-dipping subduction zone which is later affected by the HSZ