Abstract: Samples such as silicate and heavy sand in Zhalantun region are collected，tested and analyzed.Among these,w(SiO₂) is from 70.10% to 75.97%，and w(Al₂O₃) is from 12.50% to 15.60%，which belong to the acid rocks and SiO₂，Al₂O₃ are over saturated.Sub-alkaline rocks are the main component of the samples，w(K₂O) is from 4.20% to 5.77% with average of 4.05%，and w(Na₂O+K₂O) is from 7.56% to 9.95% with average of 8.62%.The samples are enriched in LILE such as Rb、Ba、Sr，but the HFSE such as Nb、Ta、P、Ti and HREE are less relatively.So，anomaly is obviously in the primitive mantle spider diagram.Based on calculation method of the CIPW standard mineral percentage by weight，δ Eu is from 0.05 to 0.68 with average of 0.38 ;δ Ce is from 0.88 to 1.02 with average of 0.98.The volcanic rocks samples are conducted to make isotopic dating analysis by means of LA-CIP-MS technology.According to the age harmonic graph and weighted graph，age of the volcanic rocks in the Zhalantun region is from 125 to 135 Ma，so the volcanic rocks belong to the early Cretaceous Baiyingaolao formation.Comprehensively analyzing the characteristics of the Zhalantun volcanic rocks and combined with the research results of other people，it is found that the early Cretaceous Baiyingaolao formation in Zhalantun region was formed in ancient Asia or mantle with fluid metasomatism and crystallization differentiation related by Mongolia-Okhotsk ocean close.

Key words: Baiyingaolao formation, Lithogeochemistry, Fluid metasomatism, Crystallization differentiation