Research On The Structural Evolution Of Weibei Uplift In Baoji,Shanxi

The Longxian-Qianyang-Qishan area in northern Baoji,Shaanxi,is located at the junction of the Qilian-Qinling orogenic belt and the Ordos block.Since the late Mesozoic,the two major tectonic units have experienced multi-stage tectonic movements with different properties,forming a complex between them.Diverse structural patterns,including the Liupanshan structural belt,the Weihe Basin,and the Weibei uplift.By carrying out regional geological surveys in the area and integrating comprehensive methods such as geology,remote sensing,geophysical prospecting,and drilling,data on contact relationships,sedimentary construction sequences,and degeneration characteristics between different structural units were obtained.Based on the guidance of plate structure and basin analysis theory,based on the actual stratum,structure,geophysical profile and test data,combined with the research results of previous scholars,the formation mechanism and evolution history of the Baoji area of ??the Weibei uplift are discussed.The results show that in the middle of Yanshan(before the Late Jurassic),the collisional orogeny of the Qin-Qi orogenic belt transformed into an extension stage,and the rift activity was active.During the Late Jurassic-Early Cretaceous,a series of rift basins were formed.The local squeeze contraction between the northern margin and the Ordos block caused the southwestern margin of the Ordos block to rise,and the Weibei uplift initially formed;the late Yanshanian-Hishan period(late Cretaceous-Paleogene),the Qinling orogenic belt and The overall uplift in the Ordos area was closed by the Liupanshan fault depression basin in the Late Cretaceous Sichuan movement Qinling orogenic belt.The western segment was dislocated by the left strike slip fault,and the Weibei uplift on the north side of it was further uplifted.Pliocene),the Miocene(? 8Ma)deposited hundreds of meters of Miocene-Pliocene red clay.After undergoing uplift and erosion quasi-plainlandization,the height of Weibei uplift greatly decreased,showing a gentle hilly landform.At this stage of the Pliocene(4.5 Ma ±),affected by the rapid uplift of the Qinghai-Tibet Plateau,the western section of the Weihe Basin-Qianhe Basin began to fail,and the Weibei uplift split,forming a tectonic pattern of interfacial uplift and fault depression;late Himalayan(Quaternary),due to the rapid uplift of the Qinghai-Tibet Plateau,the lakes in the Weihe Basin withdrew,and the Weibei uplift once again oscillated uplifting,formingmulti-level loess terraces,reaching the current height.