辽西四合屯地区早白垩世义县组主体由火山岩组成,中上部夹含化石的湖相沉积岩。沿四合屯新开岭至化石观察站义县组标准剖面火山岩仅底部为玄武岩,其余部位均为高镁安山岩(SiO2=52.7%~59.3%)(Wang等,2006)。对辽西四合屯早白垩世义县组高镁安山岩(122~125Ma)(Wang等,2006)研究认 The Early Cretaceous Yixian Formation in Sihetun area of ​​western Liaoning Province consists of volcanic rocks with fossil lacustrine sedimentary rocks in the middle and upper part. The basal volcanic rocks of the Yixian Formation along the Xinkailing-Fushi Observatory at Sihetun are only basalts and the rest are all anagrams (SiO2 = 52.7% -59.3%) (Wang et al., 2006). The study of the Early Cretaceous Yixian Formation of high-Mg andesite (122 ~ 125 Ma) in Sihetun, Western Liaoning Province (Wang et al., 2006)