Evolution of the Munali Intrusive Complex: Host to a carbonate-rich Ni-(Cu-PGE) sulfide deposit

• Magmatic evolution progressed from mafic to ultramafic. Formation of replacive metasomatic dunites. High MgO melts assimilated limestone forming carbonate and sulfide melts. Late stage magmatic brecciation. Ni-Cu-PGE mineralisation associated with apatite carbonate. The Munali Intrusive Complex is hosted within supracrustal metasedimentary rocks located along a major structural lineament the Zambezi Belt in southern Zambia. complex comprises unmineralised gabbro surrounded by marginal heterogeneous mafic–ultramafic breccia unit that host Ni-Fe sulfide. This range variably evolved brecciated include gabbro, olivine-gabbro dolerite, alongside younger, pegmatitic, apatite-magnetite-bearing clinopyroxenite, wehrlite dunite. most consistent model whereby early interact hot, MgO- volatile-rich contacts, causing localised metasomatism pyroxenites, progressively replacing pyroxene-rich olivine, pegmatitic ‘replacive dunites’. Sulfide characterised carbonate-rich assemblage predominately present as lenses semi-massive massive ore. enveloped almost entirely marble, yet C O isotope signatures at have revealed clear mantle signature for some sulfide, more dominant, crustally derived component. occurring displays micro macro textures signifying presence formed anatectic melting country rocks. fracture sets define coarse clasts (>1 m) indicate rock was significantly crystallised brittly deformed prior melt infiltration. Both appear independently utilised these pre-existing weaknesses producing pseudobreccia, accounting seemingly chaotic nature orebody. indication being later phase suggests did not form situ mobilised elsewhere be subsequently emplaced late system.