THE ROLE OF THE JURASSIC RIFTING AND THE ALPINE OROGENY IN THE EMPLACEMENT OF THE PB-ZN MVT ORE DEPOSITS IN EASTERN HIGH ATLAS, MOROCCO

This study aims at highlighting the role of the Jurassic rifting and the Alpine orogeny in the emplacement of the Jurassic-hosted Pb-Zn MVT ore deposits in the Moroccan Eastern High Atlas. The Moroccan High Atlas is an intracratonic rift formed during Mesozoic time and uplifted during the African-Europe continental collision (Alpine orogeny). During the Jurassic time, the NE-SW-trending normal faults and fractures were formed and affected the Jurassic carbonate host rocks. These faults and fractures are roughly parallel to the regional major faults. Field work shows that the ore is systematically hosted in these faults and fractures and particularly the ones oriented N40 to N74. These faults facilitated the formation of karstic cavities which offered open-space for the ore deposition. These normal faults were reactivated during the Alpine orogeny during which large amount of ore-forming fluids were remobilized and circulated from deep-seated basin to the Jurassic carbonate. The NE-SW-trending faults acted as conduits for the flow of these ore-bearing fluids to the loci of deposition. In regards to exploration, the NE-SW-trending faults and fractures can be considered targets for ore exploration in the studied area as well as in the High Atlas.

Keywords: Moroccan Eastern High Atlas, Pb-Zn ore deposits, Jurassic rifting, Alpine orogeny.