Abstract:

Combined with recent studies, this paper represents the crustal movements of different layers from shallow to deep in the middle segment of the northern margin of the North China Craton during Indosinian epoch through studying underplating of basaltic magma, crustmantle mixing, deformation and metamorphism at different depths, upwelling and denudation, and sedimentation and formation. Comparison of εNd(t)-ISrof igneous rocks of Late Triassic and Early Cretaceous suggested that the threshold of a new tectonic framework at Late Triassic from the depth as a response to the transformation of the global deep tectonic framework. It was the deep tectonothermal activities that caused crustal thickening and isostatic adjustments and resulted in differential uplifts of the fault blocks, which was an intracontinental orogeny that was essentially different from conventional compressional orogeny. Meanwhile, input of the mantel materials and heat also initiated the reconstruction of the lithosphere in the North China in the Early Mesozoic.

Key words:  Late Triassic, tectonic framework, fault block structure, underplating, sedimentationformation, intracontinental orogeny