Isotopic constraints on the age and source of ore-forming fluids of the Bou Azzer arsenide ores (Morocco)

The Bou Azzer district in Morocco has a long mining history since the beginning of XXst century during which it become only world producer Co from primary, hydrothermal arsenide ores. Orebodies are structurally controlled, and mainly distributed along fault contacts between Cryogenian ophiolite-related serpentinite bodies intrusive quartz diorite or, locally, ophiolitic gabbros or Ediacaran volcanic rocks. Ore formation took place through multi-stage mineralizing process that included an early stage composed by gold, quartz, chlorite, muscovite calcite, followed main sulfarsenide (subdivided into three substages, IIa: Ni-rich, ores, IIb: Co-Fe ores IIc: Fe-Co ores), ending with epithermal characterized precipitation sulfides calcite. Field relations most previous geochronologic dating pointed to post Pan-African age ore formation, coincident Hercynian orogeny. isotopic study presented this paper includes S, Pb, Rb/Sr Sm/Nd data set mineral samples deposits (Aghbar, Tamdrost Aït Ahmane), as well regional representative different lithologies occurring area. isotope was completed S analyses minerals five (Filon 7/5, Aghbar, Tamdrost, Ightem Aït-Ahmane) some whole-rock samples. Results show formed multi-episodic events connected hercynian reactivation Devonian-Carboniferous faults, supporting dating. obtained Sr, Nd signatures rocks further became isotopically modified interaction crustal material afterwards acted source ore-forming elements. Nevertheless, do not fully concur such simple scenario but quite consistent rather complex interpretation based on multi-source origin elements isotopes scavenged number both inferred basement sedimentary cover.