辽西北票四合屯地区的义县组火山岩主要由高镁火山岩组成, 其在稀土、微量元素特征方面有明显的特殊性. 首先, 具有高Mg#, 高相容元素含量的特点, 反映了火山岩有明显的幔源岩浆的特征. 同时该火山岩也具有明显的壳源物质的特征: 稀土元素总量较高、稀土元素的分馏程度较高, 高La/Nb, Ba/Nb比值;在蛛网图中表现为明显的Nb, Ta负异常和Pb正异常;在Sr-Nd-Pb同位素方面, (87Sr/86Sr)I的值较高, εNd(t)值区范围较大, 显示出富集地幔的组分特征;结合该火山岩Sr, Ba, Y, Yb的含量, Sr/Y比值的分析, 该高镁火山岩具有日本Setouchi岛弧的Sanukite火山岩的特征;说明了Sanukite不仅分布在板块边缘俯冲带附近的岛弧区, 在板块内部也可同样存在. 分析表明: 该地区高镁火山岩是幔源岩浆和地壳物质共同作用的结果. 说明辽西地区在早白垩世具有特殊的构造地球化学背景, 在中国东部地区中生代火山岩的形成中具有特殊性, 是进一步研究中国东部岩浆作用的特点, 探讨壳-幔演化(物质交换)具体进程的理想研究地区.
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