Programme des sessions > Recherche par auteur > Bonnetti Christophe

The north of the Arabian-Nubian shield is an underexplored metallogenic province for base and precious metals hosted by the Central Eastern Egypt domain and Mydian/Hijaz terranes of Saudi Arabia. A variety of deposit types have been identified, such as Cu-Zn VMS, Au-Ag epithermal located near or along ophiolites / suture-like series, and orogenic and intrusive-related gold mineral systems located both along Nabitah and Najd second-order structures, close to mafic or ultramafic lithologies, sometimes concentrated in the vicinity of syn- to late-orogenic granitoids or metamorphic core complexes (Hafafit, Nugrus and Qazaz-related domes).

This study aims to identify the spatial and genetic relations between the litho-structural context and mineral occurrences within the Nugrus-Qazaz structural belts to build tailored metallogenic models for the studied area. This GIS-based study consists of an hybrid approach to build prospectivity maps using the following steps : i) establishing the key components and mappable criteria of gold mineral systems (knowledge-driven); ii) the compilation, harmonization, reclassification and digitalisation of spatially referenced geoscientific data (e.g. harmonizing 250k maps) to obtain homogenous and accurate entry data (data-driven) ; iii) and then processing them with geostatistical tools applied on key criteria for the targeted mineral systems.

Through the review of the whole dataset, we elaborated a lithostratigraphic timescale displaying local geological events, merging groups and formations, resulting in a new harmonized classification. New metallogenic maps now highlight the key geological factors controlling the distribution of precious and base metals occurrences (e.g. basin margins, intermediate to felsic dykes, NE- to EW-trending shear zones, fertile lithologies) within a polyphased tectono-metamorphic setting from the syn-collisional Nabitah tract (ca.710Ma) to late-orogenic collapse recorded by the Nugrus and Qazaz structural domains. The latter may represent significant pathways for gold-bearing metamorphic and magmatic-derived fluid circulation in the region.

The preliminary results highlight the singular location of the Sukari, Al Wajh, Umm Lajj and Buwaydah gold districts located between two large gneissic domains, the Hafafit and Nugrus-Qazaz shear zones, near numerous syn- to late-orogenic granitoids intruded at ca.620Ma (eg. Ar Ra'al) and associated with the development of molassic carbonate-dominated basins (e.g. Thalbah basin).