Rheology of the middle crust under tectonic extension: Insights from the Jinzhou detachment fault zone of the Liaonan metamorphic core complex, eastern North China Craton

摘要: Abstract Although exhumation of metamorphic core complexes (MCCs) have been traditionally attributed to collapse orogenically overthickened crust, recent studies reveal that they can also result from extension lithosphere with normal crustal thickness. For example, there is an ongoing debate about the mechanisms responsible for Liaonan MCC, which occurred during late Mesozoic lithospheric thinning North China Craton. This paper attempts present rheological constraints on middle upper detachment faulting MCC and, therefore, genesis based a comprehensive study microstructural and fabric characteristics tectonites Jinzhou master fault MCC. The zone comprises thick sequence rocks shallow depths. Three types mylonitic characterize deformation along early Cretaceous extension. Microstructural these were formed via different crystal plastic dynamic recrystallization at temperatures ca. 300 650 °C. flow stresses depths calculated using classical paleopiezometers. suggests pre-heated crust was low faulting, somehow from, e.g., Whipple Mountain in American Cordillera. Based inferences properties associated it suggested complex by tectonic cratonic thickness, instead being typical Cordilleran-type setting crust.