Study Of High-Resolution Sequence Of Jurassic Yanan Formation In The East Of Ning Xia Province

By utilizing the principle and method of the high-resolution sequence stratigraphy and fully collecting core and well log information, this paper systemmaticaly analyzes sedimentary characteristics and divides the depositional system of Yanan formation in the east of Ning Xia province. It suggests that Yanan formation experiences meandering river system-delta system-meandering river system from bottom to top, reflecting a peak growth period in ordos basin. The emphasis of this paper is to identify, contrast and divide the high-resolution sequence interface, analyze the constitution of its internal units, identify and contrast the base level cycle. There are three kinds of cycles in Yanan formation in study area, namely short-period cycle (several), middle-period cycle (eleven) long-period cycle(four) and super-long-period cycle(one). Studies show that the long-period cycle are mainly controlled by basin tectonic activity which can be well collated in the whole area, the middle-period cycle,mainly controllde by the terrain partly and material resource, can be collated only in part area. Moreover,this paper investigates the sedimentary facies distribution under correlation of high-resolution sequence stratigraphy, studies show that sedimentary facies distribution show west to east and mainly composed of sandy channel frame, silty flood plain and muddy swamp, which are good to develop coal, and the law of coal accumulation is affected by material resource and accommodation.