New Caledonia: Geology, Geodynamic Evolution and Mineral Resources
This memoir summarizes current knowledge on the geology of New Caledonia, its geodynamic evolution and mineral resources, based on published and unpublished information. It comprises ten research papers, each addressing a particular geological assemblage or topic. After an introductory chapter and a review of the published geodynamic models of evolution of the SW Pacific, Chapters 3-5 focus on the main geological assemblages of Grande Terre: the pre-Late Cretaceous basement terranes, the Late Cretaceous to Eocene cover, and the Eocene Subduction-Obduction Complex, one of the largest and best-preserved in the world. Chapter 6 is devoted to the Loyalty Islands and Ridge. Chapter 7 deals with the mostly terrestrial post-obduction units, including regolith. Chapter 8 deals with palaeobiogeography and discusses plausible scenarios of biotic evolution. Chapters 9 and 10 provide a comprehensive review of New Caledonia's mineral resources. The volume will be of interest to stratigraphers, sedimentologists, marine geologists, palaeontologists, palaeogeographers, igneous and metamorphic petrologists, geochemists, geochronologists, and specialists in tectonics, geodynamic evolution, regoliths, ophiolites and economic geology.
Chapter 10: Mineral resources and prospectivity of the ultramafic rocks of New Caledonia
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Published:June 16, 2020
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CiteCitation
P. Maurizot, B. Sevin, S. Lesimple, L. Bailly, M. Iseppi, B. Robineau, 2020. "Chapter 10: Mineral resources and prospectivity of the ultramafic rocks of New Caledonia", New Caledonia: Geology, Geodynamic Evolution and Mineral Resources, P. Maurizot, N. Mortimer
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Abstract
The main metallic mineral resources of New Caledonia are hosted by the obducted Peridotite Nappe. Ni, Co, Cr and the Pt group elements (PGEs) are specific to this ultramafic terrane. Cr, as podiform chromitite in the uppermost mantle, is the only hypogene metal mined economically in the past. The largest chromitite deposits are located in the lherzolitic Tiébaghi Massif. Supergene Ni and Co deposits are concentrated by the tropical climate that has prevailed since the Miocene. New Caledonian lateritic Ni deposits account for 10% of the global Ni resources. Hydrous Mg silicate and oxide types coexist in a single deposit. A local genetic model based on geomorphological evolution is proposed. Sc is a prospective resource associated with these supergene deposits. The PGEs are a prospective resource associated with chromite, with potential in the hypogene, supergene and fluvio-littoral domains. Pt and Pd are the most significant elements. The transition zone between the upper mantle and crustal cumulates constitutes a regional Pt–Pd-enriched horizon. The concentrations are related to small disseminated chromite lenses in a pyroxene-rich lithology. The PGEs are concentrated in weathering profiles. The value of chromite-rich sands as placers or sand beach deposits might be enhanced by the occurrences of PGEs.
- Cenozoic
- chromite ores
- cobalt ores
- igneous rocks
- klippen
- lherzolite
- Melanesia
- metal ores
- metals
- mineral deposits, genesis
- mineral resources
- Miocene
- Neogene
- New Caledonia
- nickel ores
- obduction
- Oceania
- peridotites
- plate tectonics
- platinum group
- platinum ores
- plutonic rocks
- protoliths
- supergene processes
- Tertiary
- ultramafics
- Tiebaghi Massif
- Peridotite Nappe