Intracontinental subduction: a possible mechanism for the Early Palaeozoic Orogen of SE China

Abstract

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 40 Ar/ 39 Ar 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.