High-resolution sequence stratigraphic analysis of the braided river facies in the 3rd member of the Neogene Guantao Formation,Huanghua depression

High-resolution sequence stratigraphy in the 3rd member of the Neogene Guantao Formation,Huanghua depression,Hebei is explored on the basis of outcrops,well logs and seismic data.One long-term,two mid-term and several short-term base-level cyclic sequences have been distinguished,of which the mid-term and short-term cycles are typical of the asymmetric "deepening-upward" sequences and symmetric "deepening-upward" and then "shallowing-upward" sequences.The reservoir bodies are developed mainly in the early stages of the long-term and mid-term base-level rise.