Chapter 8: Palaeobiogeography of New Caledonia
Published:June 16, 2020
New Caledonia is known as a global biodiversity hotspot. Like most Pacific islands, its modern biota is characterized by high levels of endemism and is notably lacking in some functional groups of biota. This is the result of its distinctive palaeobiogeographical history, which can be described in terms of three major episodes relating to Gondwana, Zealandia and New Caledonia. The geological record, the fossil record and the modern biota of the archipelago are all reviewed here. The geological record shows that the main island, Grande Terre, was submerged between 75 and 60 Ma. There is a 9 myr interval without any geological record between 34 and 25 Ma, immediately after the obduction of the Peridotite Nappe. Grande Terre may or may not have been submerged during this 9 myr interval. The ages given by molecular biology, independent of any geological calibration points, form a continuous spectrum from 60 Ma up to the present day. The derived lineage ages from molecular phylogenies all post-date 60 Ma, supporting the idea of the continuous availability of terrestrial environments since 60 Ma. Of the three common scenarios for the origin of the New Caledonia biota, long-distance dispersal is the most plausible, rather than vicariance or dispersal over short distances.
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New Caledonia: Geology, Geodynamic Evolution and Mineral Resources
CONTAINS OPEN ACCESS
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knowledge on the geology of New Caledonia, its geodynamic evolution and mineral resources, based on published and unpublished information.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.