Title : The Taourirte Cu, Pb, Zn (±Ag-Au) and Ba (Western High Atlas, Morocco): example of carbonates hosted polymetallic mineralization in a polyphase magmatic context
Taourirte area is located on the eastern flank (ENE) of the Western High Atlas massif (WHA) in north of the South Atlas fault. It belongs to the Amezmiz mining district which includes several deposits and showing of polymetallic mineralization (Azegour, Tighardine, Amensif, Erdouz…).
The geological investigations carried out on the Taourirte zone, allowed us to distinguish three lithostratigraphic units dominated by volcanic and volcano-sedimentary rocks with intercalation of dolomitic beds and lenses. The Taourirte formation is correlated with the neighboring Tighardine area where an Early Ediacaran age has been proposed (1).
The geochemical and petrological studies, carried out on the volcanic rocks of the Taourirte Formation, shows that these metavolcanites are basalts, basalt-andesites and andesites with some felsic derivatives. The parent magma of these rocks is similar to that of intracontinental tholeiites derived from an enriched mantle source compatible with a continental extensional regime (2).
The main mineralized body is hosted in the basal dolomitic bar of the median unit at the contact of a shear zone that shows a quartz ± barite fill associated with sulphides. An important network of veins and slits develops in the hosted dolomites.
Four paragenetic stages generating the Taourirte mineralization are distinguished. The early stage consists of a thermal episode marked by tremolite-actinolite and talc, followed by the dissemination stage with pyrite and chalcopyrite which is accompanied by cryptocrystalline silicification of the dolomite and filling of cracks and fractures with microcrystalline quartz and dolomite (quartz I and dolomite I) in all facies. The third stage is related to a tectonic-hydrothermal event, lead to a quartz I and dolomite I brecciating. It corresponds to the main mineralizing stage during which quartz II, dolomite II, barite and the main sulphide mineralization (chalcopyrite, galena, sphalerite, pyrite, arsenopyrite, bornite and stibnite) are deposited. The late supergene stage corresponds to a filling of late developed cracks and fractures by quartz III and dolomite III. It also produces a generalized oxidation which of the mineralization.