The Wumishan Formation in Jibei Depression is of carbonate tideflat sedimentary

and can be divided into three subfacies (supralittoral zone

subtidal zone

intertidal zone) and four microfacies (upper and lower intertidal zones as well as highenergy and lowenergy subtidal zones). An analysis of trace element and oxide enrichment pattern is carried out by using factor analysis method. The result shows that the carbonates in the area are affected by terrigenous muddy water sedimentation and that there is a close relationship between its geochemical behaviors and sedimentary environment. Contents of both trace elements and oxide significantly increase from supralittoral zone to intertidal zone and to subtidal zone. As the water depth increases

the content of Sr and B

which are sensitive to carbonate sedimentary environment

and Sr/Ba

Sr/Ca and Mn/Fe ratios

rise from the supralittoral zone to subtidal zone. These features indicate that the geochemical characteristics of the area can be used as important marks for facies analysis and that the accuracy of field division of stratum and sedimentary facies is relatively high.