Daba mountains locate between the Qinling collisional orogenic belt and northea st ern border of the Sichuan cratonic basin. On the plate tectonic affinity, it sho uld be ascribed to the marginal tectonic regime of Yangtz plate. Tectonically, the mountain ranges can be divided into two tectono-stratigraphic units by the large-scaled Zhengping Chengkou-Zhongbao thrust (ZCZT), namely the northern block of Da ba mountains (NDM) and the southern block of Daba mountains (SDM). Since the late Proterozoic, the northern block of Daba mountains had underwent the geological p rocesses of tectonic extension from early Cambrian to middle Devonian (∈D2), tectonic inversion in the middle Triassic (T2) and at last in the period from middle Triassic to early Jurassic the tectonic thrusting (T2 J1). The deformation styles caused by the tectonic extension are mainly in the forms of large-scaled syn s edimentary listric normal fault system with the north dipping structural polarities. It had controlled the differential deposition of lower Paleozoic strata bet ween different fault-bounded blocks. Based on the researches of basic and ultra b asic rocks emplaced in these Palaeozoic strata on the isotopic chronology, the compositions of major elements, REE and trace elements, It has been proved that the geodynamics to form the tectonic extension was resultted from the tensile thi nning of continental crust which was dominantly caused by the upper mantle doming due to the mantle derived lithospheric rifting developped in the northern mar g in of Yangtze plate in the Palaeozoic. Later with the occurrence of Qinling coll isional orogen, the A-type subduction was initiated within the sialic crust in t he northern Daba and southern Qinling belt. Thus the tectonic inversion was take n place in the period of middle Triassic. The deformation styles formed by tectonic inversion are of the deep-seated ductile stepped detachement along the early formed normal listric faults that had caused the crustal superimposition at the depth of 10km to 35km and of the shallow brittle stepped thrusting along the in competent strata that had formed the thrusting silices, the duplex and the pup u p in the cover strata. By making the balanced cross section, The crustal shortening rate is calculated at least about 35.5-44.2% and the crust had been shorten e d about 220km with the annual shortening rate of 0.81cm. Furthermore, owing to the crustal superimposition, the cover strata were underthrusted to a great depth. As the result, the cover mobilization was formed with the greenschist faces ch aracteristed by the bearing disthene, grossularite and muscovite.