Abstract:

On the basis of observation and measurement in field, and with the application of sedimentology and high resolution sequence stratigraphy theories, a detailed study on the sedimentary characteristics of the Badaowan Formation in Sikeshu section, southern Junggar Basin has been conducted. The fan delta system developed fan delta plain and fan delta front subfacies, and the sedimentary characteristics of the two kinds of subfacies are concluded. In the outcrop, two longterm stratigraphic cycles are identified and Badaowan Formation can be subdivided into three medium-term cycles, as well as the composition of a number of short-term cycles. This paper summarized the relationship between the A/S ratio with stratigraphic stacking patterns in outcrop area. A thick stacked sand body with good connectivity was formed in the low A/S ratio condition, and the types of sedimentary microfacies are single; In the medium A/S ratio condition, thin and blanket-like monolayer superimposed in vertical, and formed compacted multilayer sand body. Mudstone and isolated sand bodies are developed in the high A/S ratio condition rifely, and their internal structures are compacted with limited lateral extension. Eventually, through detailed anatomy of the sedimentary characteristics of Badaowan Formation in the outcrop section, a fan delta sedimentary model of Badaowan Formation has been established, and provides reference for fan deltas reservoir research in southern margin of Junggar Basin.

Key words: outcrop of southern Junggar Basin, Badaowan Formation, A/S ratio, fan delta, sedimentary characteristics