Intracontinental subduction: a possible mechanism for the Early Palaeozoic Orogen of SE China |
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| Authors: | Michel Faure Liangshu Shu Bo Wang Jacques Charvet Flavien Choulet Patrick Monie |
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| Institution: | Universitéd'Orléans, CNRS/INSU, UniversitéFrançois Rabelais –Tours, Institut des Sciences de la Terre d'Orléans –UMR 6113, Campus Géosciences, 1A rue de la Férollerie 45071 Orléans cedex 2, France;;State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;;Department of Earth Sciences, Nanjing University, Nanjing, China;;Géosciences Montpellier, UMR 5243, Universitéde Montpellier 2, 34095 Montpellier, France |
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| Abstract: | The Early Palaeozoic Orogen of SE China consists of three litho-tectonic elements, from top to bottom: a sedimentary Upper Unit, a metamorphic Lower Unit and a gneissic basement. The boundaries between these units are flat lying, south directed, ductile decollements. The lower one is coeval with an amphibolite facies metamorphism (M1). The belt is reworked by migmatite–granite domes, high-temperature metamorphism (M2) and granitic plutons related to post-orogenic crustal melting. We date here the syn-M1 ductile shearing at 453 ± 7 Ma by U-Th/Pb method on monazite. Previous ages and our new 40Ar/39Ar ages of biotites and muscovites show that the metamorphic rocks experienced syn-M2 exhumation from 440 to 400 Ma. The Early Palaeozoic Orogen of SE China is an intracontinental belt in which decollements accommodated the north-directed subduction of the Cathaysian continent. This orogen is an example of intracontinental subduction that was not preceded by oceanic subduction. |
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