Metallogenic Mechanism Analysis Of Pv^ai Metamorphosed Volcanic-hosted Massive Sulfide Deposit In Shirui Region Of Ethiopia

Shirui region of northern Ethiopia, belongs to Nubia shield of Arab-Nubia shield in the northern West Gondwana, and is located in the southwestern extending area of Asmara VMS copper metallogenic belt in Eritrea, and presents the prospective potential of mineralization. The crustal evolution of this region is complex. The tectonic setting is still controversial. The deposit is intensely subjected to the regional metamorphism, which makes the deposit genesis unclear and the prospecting difficult. Based on collecting previous literature, field geological survey and sampling, identification of thin sections and polished sections of the wall rock and ore, the geochemistry, isotope and genetic mineralogy of pyrite analysis, the following conclusions have been obtained.Shirui region has undergone the breakup of supercontinent, the plate subduction convergence, the plate cracking associated in proper order. The metallization of the area is on intimate terms with plate subduction and convergence environment.The occurrence of metamorphosed volcanic in Shirui is stable in general, which basically is in northeast band. The lithologies and lithofacies of volcanic are complicated. The lithology ranges from basic to acid.The lithofacies consists of volcanic eruption facies, volcanic flooding facies, volcanic sedimentation facies, normal sedimentation facies and intrusion facies. The diagenetic age of the volcanic formed at the subduction zone of the plate margin is831Ma±15Ma. The source rock is the volcanic which is separated and crystallized from mantle-derived melts and assimilated the crustal materials during the process of crystallization and differentiation.The genesis of the deposit is considered to be sub-volcanic hydrothermal filling and replacement and alters by late hydrothermal. Ore bodies is mainly deposited in intermediate-acid crystal tuff and tuffite. The initial deposit were formed in the Pvai volcanic where ore-forming materials were originated from volcanic and sub-volcanic hydrothermal created by eruption, and then enriched to be ore deposit after suffering from regional metamorphism in late stage that the protore were reformed by metamorphosed hydrothermal and metallogenic materials were activated.