In late Cenozoic, high speed and large thickness sediment, lacustrine bog facies, fairly weak fault movements in central Wuqing sag, resulted in biogenic and biogenic-thermo-catalytic gas pool with large possibility.
The four types of n \|alkanes are recognized: ① back\|crest odd\|predominant n \|alkanes, generally occurring in the inland lake\|delta plain bog and lacustrine bog;
The profiles of these two types of paddy soils may be written as A-P-W- ⅡM-ⅡG1-ⅡG2 for soils developed on the Bluish Purple Clay originating from marine deposit, and A-P-W-Ⅱ W1-ⅡW2-Ⅱ C for those developed on the Quaternary Red Clay.