Exhumation of plutons controlled by boundary faults: Insights from the kinematics, microfabric, and geochronology of the Taibai shear zone, Qinling Orogen, China

Abstract The Taibai granitic plutons lie between the ductile shear zone to north and Shangdan suture south. deformation mechanism of shearing is crucial understanding exhumation processes multiple that formed after Late Mesozoic period. Geological investigations, microstructures, kinematic vorticity calculations indicate deformed in response pure shear-dominated (54%–65%) transpression top-to-NW sense as a result NE–SW oblique contractional tectonics. quartz crystallographic preferred orientations prism <a> slip system, grain boundary migration, sub-grain rotation dynamic recrystallization quartz—combined with plagioclase–hornblende thermometer—constrain main temperatures range 400–650 °C, which suggests amphibolite greenschist facies conditions. In addition, it extremely likely mylonites experienced late-stage, lower temperature demonstrated by sporadic bulging recrystallization, basal two-feldspar geothermometer calculation. samples collected from weakly mylonitic granite pluton undeformed quartz-feldspathic dike intruded into yield zircon U–Pb ages 129 ± 1 Ma 115 Ma, respectively. This information, intercept ca. 120 obtained mylonite samples, probably occurred Ma. Combined regional geological data, these findings suggest accommodated upward extrusion during Early Cretaceous time.