Lithostratigraphy, Whole-Rock, and Sm–Nd Isotopic Data of the Ediacaran Magmatic Rocks from the Zgounder Ag–Hg Deposit (Siroua Massif, Central Anti-Atlas, Morocco)

In the Zgounder Ag-Hg high-grade deposit, Ediacaran magmatic rocks of different types and compositions have been intruded by several dolerite and rhyolite dike swarms. This contribution focuses on the 610–541 Ma period of the Zgounder mine region, starting with the volcano-sedimentary successions of the Bou-Salda Group (610–580 Ma), represented in the studied area by the Tadmant rhyolite. The overlaying Ouarzazate Group (580–541 Ma) consists predominantly of volcano-sedimentary series intruded by contemporaneous multi-pulses of felsic plutons. Geochemically, two magmatic associations are distinguished: (i) mafic metaluminous rocks of within plate and calc-alkaline to transitional affinity; and (ii) felsic-intermediate rocks of peraluminous and high-K calc-alkaline signature. For all of the samples, the hybrid isotopic signature (εNd(570) = − 0.9 to + 4.3) and the calculated TDM model ages from 1197 to 1526 Ma indicate mixing between a depleted mantle source with an enriched source (probably a Paleoproterozoic crust). These findings suggest that the Ediacaran magmatism of Zgounder deposit was emplaced in a long-lived syn-to-post-collisional environment during the metacratonic evolution of the northern edge of the West African Craton (WAC). During this period, huge volumes of mostly felsic magmas, typical of a Silicic Large Igneous Province (SLIP), were emplaced during multiple pulses. The last two pulses, at the final stage of the Pan-African orogeny (560–550 Ma), seem to be responsible for a pervasive hydrothermal activity recorded over the whole Anti-Atlas. Consequently, this hydrothermal activity led to the formation of numerous world-class precious and base metal porphyry-epithermal deposits, including the investigated Ag-Hg Zgounder deposit.