UPLIFT BEDDING-DELAMINATION STRUCTURE $$$$ AN EXAMPLE FROM PALAEOPROTEROZOIC OROGENIC BELT IN LIAODONG PENINSULA, CHINA

摘要

While Liaodong palaeo-rift was still in the tectonic setting of preorogenic extension at the first stage (D_1) before Luliang movement, uplift bedding-delamination structure (UBDS) formed. It is shown that, from structural observation and analysis, the position of local uplift is the same as that of the southern batholith. Core of UBDS consists of syntectonic monzonitic granite (so-called Liaoji granite) emplacing as sheet along the contact plane between cover and basement in Western and Eastern structural provines. The local uplift resulted in the multilayered de-lamination of ductile shearing and the rheid fold layers in cover. Pinch-out of rheid fold layers could happen during progressive shearing. Some large-scale structural lenticles, in which primary sedimentary structures have been well preserved, were formed by deformation partitioning during the formation of bedding ductile shear belts and rheid fold layers formed. It is further shown that, from the statistics of stretching lineations and the direction indicators of rheid fold, the initial uplift was located in the southern batholith. Some currently observed dome folds formed by shortening of Luliang movement at the later stages (D_2 & D_3) inherited the initial uplift. The Liaoji granite was still plastic to move toward the cores of anticlinoria and re-emplaced in diapir. So the Liaoji granites regularly distributed in the cores of dome folds. Based on this example and other researches, we propose a new extensional tectonic model.