1. College of Earth Sciences, Jilin University, Changchun 130061, China;
2. Tianjin Navigation Instrument Research Institute, Tianjin 300131, China

Intermediate-acidic volcanic rocks and pyroclastic rocks exposed in the Baita area of western Liaoning are mainly composed of trachyandesite, rhyolitic breccia ignimbrite, trachydacite and rhyolite. Geochronology studies via zircon LA-ICPMS U-Pb isotopic dating show that volcanic rocks of the research area formed from 149 to 165 Ma. The geochemical study indicates that the acidic volcanic rocks belong to the calc-alkaline series, while the intermediate volcanic rocks belong to alkaline series and mid-high K calc-alkaline series. The intermediate rocks geochemically belong to adakitic rocks, with SiO₂ �� 56.20%, Al₂O₃ �� 15.09%, MgO �� 2.89%, Sr �� 561×10^-6, Y �� 13.15×10^-6, Yb �� 1.47×10^-6 and no obvious Eu anomaly. The volcanic rocks in the study area are generally enriched in LILE(Rb, K, Ba, Sr and Pb)and LREE, and depleted in HFSE (Ti, Nb, Ta and P). The original magma was derived from partial melting of the basic materials of lower crust, in the intraplate compressive orogenic background under the influence of the Paleo-Pacific plate subduction.