Pan-African SEDEX massive sulfide deposits of Abu Samar, Southern Red Sea Hills, Sudan. 2- Metamorphism.
Abstract
The Abu Samar massive sulfide and Ba-Mn deposits and the adjacent occurrences (Allaikaleib, Bashikwan and Tolik) in the Tolik gneissic and migmatized series were subject to repeated pervasive deformation and metamorphism. The ores, together with their host rocks, were first regionally metamorphosed to the granulite facies in the katazone. This promoted the wide spread crystallization of sillimanite, kayanite, and andradite garnet. Then the metamorphic grade was raised due to the emplacement of the subduction-related granodiorite plutons that generated contact metamorphism that manifested in the appearance of cordierite, phlogopite, corundum and spessartine. Finally, during the Arabian-Nubian uplift, the whole system was retrogressively metamorphosed to the green schist facies metamorphism and supergene alteration in the epizone that promoted pennine, chlorite, and muscovite. Consequently, the ores underwent repeated remobilization, recrystalliztion and granulation.
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