The geological evolution of New Caledonia may be divided into three phases.The Gondwanan phase(Permian–Early Cretaceous),is marked by subduction along the SE Gondwaland margin.At that time,proto-New Caledonia was loc...The geological evolution of New Caledonia may be divided into three phases.The Gondwanan phase(Permian–Early Cretaceous),is marked by subduction along the SE Gondwaland margin.At that time,proto-New Caledonia was located in a fore-arc region in which volcanic-arc detritus accumulated;whilst accretion and subduction of oceanic and terrigenous material formed an accretionary complex metamorphosed into the blueschist facies.During the Late Cretaceous–Eocene,marginal rifting isolated New Caledonia,and after a short period of shallow water terrigenous sedimentation associated with minor volcanic activity,only pelagic sediments accumulated.A new NE-dipping subduction appeared to the E of New Caledonia at the Paleocene-Eocene boundary,it generated the eclogite-blueschist complex of northern New Caledonia,consumed the eastern Australian Plate,and eventually ended with Late Eocene obduction when the Norfolk Ridge blocked the subduction zone.Finally,during the post-Eocene phase,New Caledonia definitively emerged;this episode mainly corresponds to prominent regolith development and minor tectonic events that lead to the present morphology and to the development of supergene nickel ores.展开更多
文摘The geological evolution of New Caledonia may be divided into three phases.The Gondwanan phase(Permian–Early Cretaceous),is marked by subduction along the SE Gondwaland margin.At that time,proto-New Caledonia was located in a fore-arc region in which volcanic-arc detritus accumulated;whilst accretion and subduction of oceanic and terrigenous material formed an accretionary complex metamorphosed into the blueschist facies.During the Late Cretaceous–Eocene,marginal rifting isolated New Caledonia,and after a short period of shallow water terrigenous sedimentation associated with minor volcanic activity,only pelagic sediments accumulated.A new NE-dipping subduction appeared to the E of New Caledonia at the Paleocene-Eocene boundary,it generated the eclogite-blueschist complex of northern New Caledonia,consumed the eastern Australian Plate,and eventually ended with Late Eocene obduction when the Norfolk Ridge blocked the subduction zone.Finally,during the post-Eocene phase,New Caledonia definitively emerged;this episode mainly corresponds to prominent regolith development and minor tectonic events that lead to the present morphology and to the development of supergene nickel ores.
