Abstract:

In accordance with the division and correlation of sequence stratigraphy, the Karashayiand Xiaohaizi Formations can be classified into two sedimetary sequences which reflect twoeustatic changes of sea level. The isochronal deposit surface between two sequences is theboundary between Karashayi and Xiaohaizi Formations. Karashayi Formation consists alternately of coastal plain factes and fan-delta factes, whereas the Xiaohaizi Formation consistsmainly of shelf factes and fan-delta factes. However, the fan-deltas in the two sequences arerespectively deposited in high-stand rapidrise of sea level, and they both have wet fan-deltafeature.