苏北牛山片麻状花岗岩形成于震旦期，富含碱性长石，普遍含有碱性镁铁矿物，具有高硅、富碱、低铝、贫水，富含Ｎｂ、Ｚｒ、Ｙ、Ｇａ、ＲＥＥ及Ｅｕ明显亏损等特征，为Ａ型花岗岩。其Ｙ／Ｎｂ、Ｙｂ／Ｔａ、Ｃｅ／Ｎｂ等比值较高，Ｇａ×１０４／Ａｌ和碱度较低，属Ａ２亚型花岗岩。它是苏胶造山带在晋宁期碰撞造山后的拉张环境下，由地幔热流上涌，致使下地壳岩石部分熔融，产生的岩浆于中地壳侵位而形成。 The Beishan gneissic granite in the northern Jiangsu Province was formed during the Sinian period and was rich in alkaline feldspar. It generally contained alkaline mafic minerals with high contents of silicon, alkali, low aluminum, water, Nb, Zr, Y, Ga, REE and Eu obvious loss characteristics for the A-type granite. The ratios of Y / Nb, Yb / Ta and Ce / Nb are relatively high, while Ga × 104 / Al and alkalinity are lower, belonging to A2 sub-type granites. It is the Su-plastic orogenic belt after the Jinning period collisional orogeny stretching environment, upwelling by the mantle heat flow, resulting in partial melting of the lower crustal rocks, the resulting magma formed in the mid-crust emplacement.