北秦岭存在一套低Al的奥长花岗岩-英云闪长岩-闪长岩系列岩石,其形成时代在430~399Ma之间,并具有正εNd(t)特征.地球化学特征和微量元素模拟计算表明,它们由二郎坪群中的变拉斑玄武质岩石重熔而来,不同残留相和熔融程度形成了不同岩石类型.重熔过程残留相的热力学分析显示,该岩石系列代表温度升高、压力降低的过程,表明存在加厚地壳的拉张减薄作用. In the North Qinling Mountains, there exists a series of low-Al-granodiorite-amphibolite-diorite series rocks with a positive εNd (t) age of 430 ~ 399Ma.Geochemical characteristics and trace element simulation Calculations show that they are remelted from the stratified rock basalt in Erlangping Group, and different residual phases and degrees of melting formed different rock types. Thermodynamic analysis of the residual phase in the remelting process showed that the series of rocks represented a rise in temperature , The process of pressure reduction shows the existence of thickened crustal pull thinning effect.