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南秦岭勉略构造带黑沟峡变质火山岩(绿泥钠长片岩)的主要元素组成表明,它是一套双峰式火山岩系,由低K富Na拉斑玄武岩及酸性英安岩、流纹岩组成.该玄武岩具有类似MORB的痕量元素特征,扁平的REE模型,但富Th和Pb已获得该变质岩系的Sm-Nd全岩等时线年龄为242±21Ma,Rb-Sr全岩等时线年龄为221±13Ma,它们在误差范围内一致,并指示该火山岩系的变质时代.变质时代的初始ε_(Nd)值(+6.1)指示该玄武岩源区为MORB型亏损地幔(ε_(Nd)值>+6.1).
The main elemental composition of the Heigouxia metamorphic volcanic rock (chlorite-long slate) in the Mianleo structural belt of the South Qinling Mountains indicates that it is a bimodal volcanic series consisting of low K-rich Na-lavas basalt and acidic dacite, The composition of the basalt is similar to that of the MORB trace element and the flat REE model. However, the Sm-Nd whole-rock isochron age of 242 ± 21Ma, Rb-Sr whole rock The isochron age is 221 ± 13Ma, which is consistent within the error range and indicates the metamorphic age of the volcanic series.The initial ε Nd value (+6.1) in the metamorphic age indicates that the basalt source zone is a MORB depleted mantle (ε_ (Nd) value> +6.1).