Chapter 9 Mineral resources and prospectivity of non-ultramafic rocks of New Caledonia

The mineral resources of the non-ultramafic rocks of New Caledonia and its Exclusive Economic Zone can be classified according to their host rocks. The metallic mineral resources are essentially associated with volcanic and magmatic activity. Non-economic volcanogenic massive sulfide deposits with Cu and Au are located in the Late Carboniferous Koh Ophiolite and in the Late Cretaceous Poya Terrane. Base metals, Au and Ag of the sedimentary–exhalative type are present in the metamorphic Diahot-Panié Metamorphic Complex, associated with syn-rift volcanism. An Au–Sb metallogenic province is associated with the post-obduction Late Oligocene granitoids and co-genetic hydrothermal silica–carbonate (listwanite) zones in the Peridotite Nappe; Au is disseminated in the granites and Sb occurs as lodes in the silica–carbonate. Among the non-metallic mineral resources, barite, gypsum, magnesite, phosphate, clays, dimension stones, limestone for use as cement and as a neutralizer, and aggregates are all present. Gemstones such as jade and chrysoprase are only used locally. Late Cretaceous coal, which was briefly exploited in the past, is now considered to be a source rock for an offshore potential oil and gas system. Petroleum prospectivity is currently focused on the Fairway Basin. Several low-enthalpy thermo-mineral springs with a weak geothermal energy potential are known on Grande Terre.