The inner zone of the liaoji paleorift: its early structural styles and structural evolution

Abstract A suite of eugeosynclinal formations, together with common occurrence of extensional granitic rocks, constitutes the major part of the inner zone of the Liaoji Paleorift in Liaodong Peninsula, China. Two characteristic associations of deformation structures formed under different crustal conditions have been recognized in the Liaoji Paleorift zone from macro-, meso- and micro-structural studies and tectono-thermal analyses. Magmatic Core Complex (MCC), a special structural style of extensional regime inherited from early rifting, is constituted by the spatial, temporal and genetic associations of magmatic cores, bedding-parallel ductile shear zones and extensional nappes. Such complexes are widely developed in the rift zone. Superposed on the MCCs thrust-nappes and thrusting-related brittle-ductile shear zones dominate a compressional event in the later evolution of the rift zone. Early structures were strongly deformed and transformed by later structures, and meanwhile also exerted control on the latter, e.g. the thrust-nappes are often related to early folds and represented by fold-nappes with extensive reactivation and reemplacement of granitic rocks in the cores. A schematic evolutionary model for the early structural evolution of the Early Proterozoic in the inner zone is presented, which indicates a different evolution of early rift zones from those of younger ones.