The Evolution Of Mesozoic-Cenozoic Basin-range Structure And Tectonic Stress Field In The East Yanshan Area And Xialiaohe Basin

The east Yanshan area and Xialiaohe Basin located in the north part of North ChinaBlock (NCB) used to be referred to as two tectonic elements which belong to Yanshanorogenic belt and Xialiaohe Basin respectively, and are studied separately by manygeologists for a long time. After analysing comprehensively the Mesozoic-Cenozoicorogenesis, basining, researching geophysical and geological features, the evolution ofMesozoic-Cenozoic basin-and-range and tectonic stress field in the east Yanshan area andXialiaohe Basin the author holds that the orogenic belt and sedimentary basin are a differentmanifesting form with each other's genetic relationship in the structural evolution process oflithosphere, although they are different in structural form. The evolution process ofMesozoic-Cenozoic geological structure in the east Yanshan and Xialiaohe basin is eachother's transformation process of orogenics and basining in the space and timeThe Mesozoic-Cenozoic structures in the east Yanshan and Xialiaohe Basin areintracratonic (intracontinental or intraplate) basin-and-range structure zone andorogenic belt developed in the basement of pre-Mesozoic North China Craton lithosphere.The structure evolution process in the area since Mesozoic experienced five periods ofsedimentary basin evolution (Early and Middle Triassic relict cratonic basin, Late Triassicto Early Jurassic piled-up sedimentary basin, Middle and Later Jurassic fault basin,Cretaceous fault basin and Cenozoic rift basin) and five compressional deformation(compression orogenesis) stages (the end of Middle Triassic, Early Jurassic, LaterJurassic, Cretaceous and Paleogene). The structure evolution process possesses anevolution character of "accordion type"Both of compression and extension play an important role in the Mesozoic-Cenozoicstructural evolution in the area. By and largely, the compression changes from strong toweak, and the extension from weak to strong, and the compression and extension appearalternatively, associated Compressional structures and extensional structures developedalternatively. The Mesozoic-Cenozoic extensional structures include metamorphic corecomplex, basin-and-range structure and rift basin. It also shows in Cenozoic basaltic volcaniceruption. Because of the Mesozoic-Cenozoic compression the five-phase compressionalstructural features were formed in the ends of middle Triassic, early Jurassic, late Jurassic,Cretaceous, and Paleogene. The compression not only resulted in withering or disappearingof the Early and Middle Triassic, Later Triassic to Early Jurassic, Middle and LaterJurassic, Cretaceous and Cenozoic basins, but also made them deform or was responsible forthe basin reversion. Based on field survey and microstructure analysis the author considered thatYiwulvshan is a Cretaceous metamorphic core complex, and pointed out the time ofYiwulvshan granite is not early Yanshanian by the comprehensive analysis of the regionalstructures and isotopic dating, but a late Yanshanian granite. The author researchedsystematically the fault activity in different ages since Mesozoic-Cenozoic, compiled thesynsedimentary fault maps of Xialiaohe basin in Sasi, Sasan, Sayier, Dongying stages and theend of Paleogene in Xialiaohe basin. The Nantianmen fault developed in Yanshanian stage ofMesozoic in Beipiao city, Liaoning Province, is certified a Quaternary active fault cuttingPleistocene Malan loess from field survey, ESR dating of fault gouge, and OSL dating ofhangingwall loess. The author discussed systematically the evolution of tectonic stress field inMesozoic-Cenozoic according to the patterns of tectonic deformation in the different stagessince Mesozoic-Cenozoic in the area, the systematically measurement of Mesozoic-Cenozoicpaleostress and present stress, and the photoelastic modeling of Mesozoic-Cenozoic tectonicstress field.