127 / 2016-12-13 23:20:14

Geology, geochemistry and chronology of the Matchless deposit, Namibia

12087,12088,12089

The Matchless deposit is part of 4 clusters of 18 individual Volcanogenic Massive Sulfides (VMS) cupriferous pyrite deposit intimately associated with the Matchless member which is intercalated within the schistose Kuiseb formation. The Kuiseb Formation consists of metamorphosed turbiditic and immature clastic sediments and the matchless member is mainly a long belt (350 km) of metabasalt and meta-gabbro (ophiolites). The intimate association of these deposit with terrigenous clastic rocks and marine mafic volcanic and subvolcanic rocks, as well as the common development magnetite quartzite is considered indicative of a Besshi-type environment. The deposit geology, ore mineral paragenesis deformation, metamorphism and regional tectonics coupled with the H-O isotope systematics of the Matchless deposit reveal a superimposition of three hydrothermal regimes:(1) a primary Besshi type VMS (2) Syntectonic remobilization (metamorphic devolatilization) into structurally controlled ore shoots and (3) and lastly an enrichment period due to supergene processes.