Volcanic rocks are the main basin fillings during the formation of fault depression in the Songliao Basin

and their accurate dating is the basis of the rifting timing and layer subdivision.Twenty volcanic rocks samples were collected from the Changling Fault Depression and dated with LA-ICP-MS zircon U-Pb ages.Zircon U-Pb dating shows that the previous recognized Huoshiling Fm volcanic rocks formed between 110～119 Ma and should be grouped into the 1

st

Member of the Yingcheng Fm.While the previously recognized Yingcheng Fm volcanic rocks formed between 100～109 Ma and should be grouped into the 3

rd

Member of the Yingcheng Fm.Petrologically

the volcanic rocks are composed dominantly of andesite

trachyte

rhyolitic tuff and rhyolite

which are displayed in TAS diagram.Geochemical data show that the volcanic rocks have similar features such as light rare earth elements enrichment and negative Eu anomalies

indicating their affinity.As the deepest structure unit in the southern Songliao Basin

new layer subdivision and correlation strategy need to be proposed.And the results also indicate that the syn-rift stage of the southern Songliao Basin started at the Early Cretaceous rather than the previously believed Late Jurassic

which means the corresponding structure-sedimentary and hydrocarbon formation history need to be further recognized.