Formation And Evolution Of Luoyang-Yichuan Basin And Its Relation With Hydrocarbon

Luoyang-Yichuan basin is a multicycle superimposed continental sedimentary basin in middle Cenozoic, east of China. The basin has gone through such evolution stages as craton passive continental margin basin in Pre Mesozoic, depression basin in early Mesozoic, foredeep basin in late Mesozoic and fault depression basin in Cenozoic, etc. The Tectonic evolution of the basin is characterized by obvious multicycle superposition and multi-tectonism.Luoyang-Yichuan basin has been explored for nearly 50 years, although it shows better oil and gas evidence in upper Triassic in Tanzhuang group, it's lack of effective methods and limitded by complicated ground surface conditions etc, so the basin is just lower developed at present.Taking the plate tectonics as leading theories, combining outcrop, seismic techniques, drilling and logging datum, inter-verifing manifold researching methods, The paper has amply researched the region. discussed the coupling relation of basin-mountain and the geodynamics system; analyzed geologic tectonic characteristics of the basin; confirmed superposed alteration in Mesozoic of the basin; recompartmentalized tectonic units of the researching region and the basin; studied the tectonic evolution of the basin since Mesozoic; ascertained four large tectonic layers and five tectonic evolution process stages in different ways of formation and tectonic alteration; established different tectonic stages,compages,models and sedimentary filled processes, based on the organic geochemistry and oil-gas geologic characteristics in middle Cenozoic of the basin, the conclusions have been summarized in the paper, such as:The primary source rock in lower Permian and subordinate source rock in upper Triassic are developed in the region with better quality, and secondary hydrocarbon is possible; The bearing system which is comparted by three large tectonic layers and two unconformity surfaces formed in Palaeozoic,upper Palaeozoic to Triassic and Cenozoic developing in the region, compounded with reservoirs of different lithology is developed in the region, while the property of tectonic fracture reservoir is better; Based on the analyzing petroleum accumulation elements and preserving conditions, the deep depressing belt in the north of Luoyang depression,Shiling-Yiyang folded fault belt in Yiyang depression and wide anticline belt in Yichuan depression are advantageous petroliferous region, Zhaizhen anticline in Luoyang depression and Shimen wide anticline on footwall of overthrust in Yichuan depression are optimum tectonic traps.