Comprehensive correlation of the Yixian Formation in the Beipiao and Yix ian areas,western Liaoning

The comprehensive correlation of the Yixian Formation in the Beipiao and Yixian areas has long been a controversial problem.A comparative study of the petrology,geochemistry and isotope chronology at the typical sections of the Yix ian Formation in the two areas indicates that the horizon con-taining bird fossils(the Jianshangou lay er)and the Yixian Formation below the horizon in the Sihetun area,Beipiao,may correlate with the Zhuanchengzi layer of the Yixian Formation and the horizon below the layer in the Yixian area,but cannot correlate with other horizons of the Yixian Formation in the Yixian area.The determination of the relation of the Yixian Formation in the Beipiao and Yixian areas has great significance to the intensive study of the ages of the top and bottom of the Yixian Formation,scale and intensity of volcanic activities and lateral changes of the sedimentary-ecological environment in western Liaoning.