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江西南部寻邬县的白面石盆地,分布一套菖蒲组基性玄武岩与酸性流纹岩互层的火山岩组合。其Rb-Sr等时线年龄:玄武岩为173Ma,流纹岩为165Ma,说明这是一套中侏罗世双峰式火山岩。通过进一步的同位素研究,玄武岩具有高ε_(Sr)及近于零的ε_(Nd)值,显示其明显受到地壳物质的混染;流纹岩则以其高ε_(Sr)及低ε_(Nd)值,表现为地壳成因。
In the white-faced stone basin of Xunwu County, southern Jiangxi, a volcanic assemblage of ancillary basaltic and acidic rhyolites is distributed in the Changpu Formation. Its Rb-Sr isochron age: basalts for 173Ma, rhyolite for 165Ma, indicating that this is a set of bimodal Jurassic volcanic rocks. Through further isotope studies, basalts have high ε_ (Sr) and near-zero ε_ (Nd) values, indicating that they are obviously contaminated by crustal materials. Rhyolite is characterized by its high ε Sr and low ε Nd, ) Value, showing the cause of the crust.