Li Zengxue

Marine Transgression “Event” in Coal Formation from North China Basin

Many geologists believe that coal seams were formed under shallow water conditions or continental environments in marine regression. Coal seams were regarded as final results of basin evolutions. After the study of the coal formation characteristics and sequence stratigraphy of the megaepeiric sea in the Late Palaeozoic, North China, the authors of this paper believe that coal formation under conditions of marine transgression is predominant characteristics in the North China Basin. Coal seams as a system tract of transgression stratigraphy are the first results of upward movement of the basin. Normally, marine transgression is a progressive movement, but authors believe that marine transgression in the North China Basin is rapidly in a short time according to the sediment sequences. They name this type of marine transgression as an “event”. According to the in-filling characteristics of sediments in the Epeiric Sea of North China, the transgression sediments by “events” are synthems, which are important for recognition of bounding surface of sequence stratigraphy. The coal seams plus their roofs of marine sediments and coal seams plus their base sediments, could be important surfaces. These surfaces could be as bounding surfaces of sequence stratigraphy or as bounding surfaces of megasequences.

Lithology Recognitions of Coal-Bearing Strata on BP-ANN in Qiongdongnan Basin, Sea of South China

Lithology identification of coal-bearing Strata has been a difficult problem in the geology for a long time, especially in the deep sea area. So it is very significance for us to study the mathematics way to recognize the coal-bearing lithology of well logs. In this paper, BP-ANN was introduced to apply to the predicate the lithology. And take the Qiongdongnan Basin as an example, the Yc13-1-a1well samples was used. By the study of it, the result was found correctly. So this way is useful and may be popularized.