中文摘要：

火山岩是松辽盆地断陷期盆地充填的主体，其年龄的精确标定是认识盆地裂陷启动时间和地层划分对比的基础。系统采集了长岭断陷20件火山岩样品，进行了LA－ICP－MS锆石U－Pb同位素分析。锆石U－Pb测年结果显示，原定火石岭组的火山岩形成于110～119 Ma，应划归为营城组一段；原定营城组的火山岩形成于100～109 Ma，应划归为营城组三段。所选火山岩样品鉴定为安山岩、粗面岩、流纹质凝灰岩和流纹岩；在TAS图解中落入流纹岩、粗面岩以及粗面英安岩区域。两个年龄区间的火山岩具有相似的地球化学特征，如铕负异常和稀土配分曲线都为轻稀土富集的右倾斜型，进一步暗示了二者的亲缘性。作为松辽盆地南部最大的深层构造单元，长岭断陷的火山岩地层序列需要重新厘定；松南地区火山－裂谷作用起始于早白垩世晚期而非晚侏罗世，相应的盆地构造－沉积史和油气形成演化史也需要进一步认识。

英文摘要：

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 pre-vious recognized Huoshiling Fm volcanic rocks formed between 110～119 Ma and should be grouped into the 1st Member of the Yingcheng Fm.While the previously recognized Yingcheng Fm volcanic rocks formed between 100～109 Ma and should be grouped into the 3rd 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 Ear-ly Cretaceous rather than the previously believed Late Jurassic,which means the corresponding structure-sedimentary and hydrocarbon formation history need to be further recognized.