Relationship Between River Cross Section Characters and Change of Ancient Geography of Offshore in Qingdao Bay

Key words: 
• Qingdao offshore /
• earthquake section of shallow stratum /
• buried ancient rivers channel /
• characters of section /
• mechanism of formation

Abstract: Based on high resolution seismic profiles surface of offshore 1 561 km nearby Qingdao, we discovered that there were multistage developed ancient river ways in this area and river sedimentary system was not well preserved in many stratums in the most of them only some of the river subfacies stratums are preserved. The character of river cross section to the east of 120°30′is relatively well preserved. The data of age measurement showed that these rivers were mostly formed 37 000～11 000 years ago, that the largest burial depth(from the bottom of modern sea to river bottom) of riverbed was about 32m and the usual burial depth was between 20～28 m and that the widest part of the river orientation was approximately 1 500 m. The river section can be divided into 6 types according to the present visible figures, which are watercourse developed with channel bar, flat base continuous multistage developed, steep narrow, asymmetric. This paper also includes the general analysis of formation mechanism of rivers and ancient geography environment.