Abstract:Objectives: Recently,wellpreserved Stegosaur fossils were discovered in the Lower Cretaceous Zuoyun Formation, which is a typical continental deposits, in Zuoyun area, Shanxi Province. Sedimentary facies of the Zuoyun Formation and burial environment of Stegosaur have been analysised based on geological section and sedimentology research. Furthermore, paleoclimate of the Zuoyun stage has been discussed based on aforementioned analysies. Methods: Firstly, we classify the Zuoyun Formation as a set of proluvial fan deposits based on lateral distribution and vertical thickness changes of interbedding of conglomerate and mudstone in the Zuoyun Formation. Furthermore, hydronamic mechanism of proluvial fan has been analysised and subfacies and microfacies have been recognized based on variation of lithofacies,interior fabric,sedimentary structures from the bottom to top. Results: Systematic sedimentology research have disclosed that the Zuoyun Formation belongs to typical proluvial fan deposits,produced by alternative debris flow and temporary stream flow processes. Based on lithologic characteristics and profile section structures, the Zuoyun Formation may be divide into three subfacies, namely the fan top, middle fan and fan margin, further four microfacies can be recognized in the profile, namely debris flow deposits,main ravine—channel, flood zone—flood flow zone,braided stream. Conclusions: Analysis combined with palynological and paleotological data indicates that Zuoyun area was generally dominated during Early Cretaceous by arid environment of subtropical desert periphery, accompanied by irregular alternation of arid and humid, during which catastrophic flood peak formed by monsoonal to millennial sudden rainstorm or extraordinary rainstorm may result in thick proluvial fan conglomerate—mudstone deposits.