Abstract:

Abstract:  Fifty eight samples from tectogenetic α quartz veins in Dabashan Mountain have been studied by using ESR dating method. The results showed that the evolution history of the North Dabashan Mountain (N.DBS) since the Mesozoic can be divided into three stages: 24372015 Ma (the Late Triassic), 1656912 Ma (the Late Jurassic to the Early Cretaceous) and 686 Mapresent (the Cenozoic), while the South Dabashan Mountain (S.DBS) can be divided into another correspondent three stages: 170160 Ma (the Bajocian to the Callovian), 1473941 Ma (the end of the Late Jurassic to the Early Cretaceous) and 667 Mapresent (the Cenozoic). Thus, the S.DBS is closely related to the N.DBS in structural evolution. Axial plane cleavages and fracture cleavages that represent the major strong deformation period of the S.DBS were chiefly formed in about 1472941 Ma (the end of the Late Jurassic to the Early Cretaceous) with the deformational characteristics of a piggyback type. The ESR dating of quartz veins in fracture cleavages also showed that the two terminal strata (deformed before 160 Ma) of S.DBS were involved into deformation earlier than the middle sections (deformed after 140 Ma). Since the Cenozoic, the tectogenesis of S.DBS transformed to the uplift and extensional slipping movements and became stable gradually. The ESR dating results are consistent with other geochronology evidences very well.

Key words:

Key words: ESR dating; structural evolution; Dabashan mountain; thin skinned tectonics; foreland foldandthrust belt