Study On Micang Mountain And Daba Mountain's Deep Textures And Structures

Daba mountain and Micang mountain,one of important exploration areas of Chinese hydrocarbon resources,are situated in the transition part between Sichuan basin and Qinling orogenic belt.The study about Daba mountain's deep structures is of significance to explore connection and conversion between upper Yangtze massif and Qinling orogenic belt.It's critical to explore oil and gas in the long run.The purpose of this paper is researching the distance of Daba mountain's nappe,deep structures of Micang mountain and extension of Huayinshan fault,mainly through upward continuation,derivative calculation,wavelet multi-scale analysis and cross-section manufacture of gravity and aeromagnetic data and combining with collected seismic sounding, magnetotelluric sounding and geologic data.The main recognizes show as following:The upper Yangtze massif subducted to north below the south boundary of Qinling orogenic belt,lying in the gleam of Chengkou in the shallow.In deep,the aeromagnetic data indicates that ferromagnetic basement reaches to Hongcunba fault.The distance of Daba mountain's thrust nappe should be more than 100km,while there are not large-scale thrust nappes in Micang mountain.Central Sichuan block subducted intensely to Qinling orogenic belt along Mian-L(u|¨)e zone and leaded to recoil of central Sichuan's basement,which formed Micang mountain.Defection,formed by a series of high-angle and step-like thrust faults declining from north to south,is concealed below Jurassic-Cretaceous layers in the south of Micang moutain.The northern boundary of Huayingshan doesn't end near by Huangjinkou of Xunhan city,but continues to the north in the cover.