Sb-Deposits in the Variscan Armorican Belt (France) - Potential Relationships with Basic Intrusions and High-Density Magnetic Lithologies at Depth
Résumé
Sb-deposits in the Variscan Armorican belt constitute a large part of
this resource in France notably with the La Lucette deposit (42000 tons
of Sb). Although these mineralizations are known since the 19th century,
relationships between geological features and antimony deposits remain
unclear. Here we perform a spatial statistical analysis using Geographic
Information System software (GIS), geophysical and geological data
(Ripley's function, spatial distribution analysis of geophysical values,
and distance to the nearest neighbour) in order to identify particular
geophysical zones where Sb-deposits are potentially clustering and to
assess affinity with different geological objects. We show that there
are specific ranges of gravity and magnetic values associated to
Sb-deposits. These characteristic ranges outline several zones of high
density and relatively high magnetic susceptibility that cover only 17.6
% of the surface of the Armorican Massif and contain or are close to
more than 50 % of Sb-deposits. Moreover, Sb-deposits far from these
zones are related with major faults. Our results reveal spatial
relationships between Sb-deposits, major faults and high-density and
magnetic zones that are interpreted as reflecting the occurrence of
basic rocks at depth. The use of such a statistical approach enables to
highlight geological controls of the mineralization
Origine : Fichiers éditeurs autorisés sur une archive ouverte