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长城站地区出露的第三系火山岩包括熔岩、火山碎屑岩及各种次火山岩。熔岩主要为玄武安山岩和玄武岩,普遍具有斑状结构,基质为间粒、交织结构。斑晶多为基性斜长石,也有少量普通辉石。岩石化学成分显示硅酸弱不饱和至弱饱和、低钾、钛、高钙、富铝(Al_2O_3>17%)。稀土及其它微量元素的特点亦说明该建造属岛弧火山活动的产物,基本属于钙碱性玄武岩,同时具有岛弧拉斑玄武岩的某些特征。
Tertiary volcanic rocks exposed in the Great Wall Station area include lava, volcaniclastic rocks and various subvolcanic rocks. Lava is mainly basaltic andesite and basalt, generally with a patchy structure, the matrix is intergranular, interwoven structure. Most plagioclastic plagioclase, but also a small amount of ordinary pyroxene. Petrochemical composition shows weakly unsaturated to weakly saturated silicate, low potassium, titanium, high calcium, aluminum rich (Al 2 O 3> 17%). The characteristics of rare earths and other trace elements also indicate that this is a product of island arc volcanism and basically belongs to calc-alkaline basalts and has certain characteristics of island arc tholeiitic basalts.