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琼河坝地区在志留纪—泥盆纪频繁的岩浆活动与成矿关系密切。矿集区中花岗岩ΣREE含量23.16×10-6~110.24×10-6,平均值68.19×10-6,总体上稀土含量较低。(La/Yb)N=3.23~10.97平均值为5.74,显示轻、重稀土分馏不明显,且轻稀土元素较重稀土元素富集。蒙西、琼河坝、和尔赛三个花岗岩体Sr-Nd、Pb同位素值很近,表明琼河坝花岗岩具有相近的成因。(87Sr/86Sr)i值为0.704 01~0.704 42,平均值为0.704 19;(143 Nd/144 Nd)i值为0.512 300~0.512 478,平均值为0.512 415;(208Pb/204Pb)i值17.600~17.910,平均值为17.738,(207Pb/204Pb)i值为15.410~15.547,平均值为15.459,(206Pb/204Pb)i值为37.250~38.019平均值为37.534。表现出壳幔混染的特征。εSr(t)值为-0.3~7.8,εNd(t)值为2.9~7.2,为较小的正值,表现出洋壳的特征。花岗岩Al2O3,Sr,Y,Yb和δEu的特征与埃达克岩相近,可能为俯冲洋壳熔融的产物。因此该地区众多铜矿点的出现,应该与埃达克岩有关。
The Qionghe area in the Silurian - Devonian frequent magmatism and mineralization are closely related. The ΣREE content of granite in the ore district is 23.16 × 10-6 ~ 110.24 × 10-6 with an average value of 68.19 × 10-6. Generally speaking, the content of rare earth is low. (La / Yb) N = 3.23 ~ 10.97 The average value is 5.74, indicating that light and heavy rare earth fractional distillation is not obvious, and the light rare earth elements heavier rare earth elements enrichment. The Sr-Nd and Pb isotopic values of the three granites in Mengxi, Qiongheba and Heersai are very close, which shows that the Qiongheba granite has similar genesis. (87Sr / 86Sr) i value is 0.704 01 ~ 0.704 42, the average value is 0.70419; (143 Nd / 144 Nd) i value is 0.512 300 ~ 0.512 478, the average value is 0.512 415; (208Pb / 204Pb) i value is 17.600 ~ 17.910, the average value is 17.738, the value of (207Pb / 204Pb) i is 15.410 ~ 15.547, the average is 15.459, the value of (206Pb / 204Pb) i is 37.250 ~ 38.019 and the average is 37.534. Show crust-mantle mixed features. εSr (t) values of -0.3 ~ 7.8, εNd (t) values of 2.9 ~ 7.2, smaller positive values, showing the characteristics of the oceanic crust. The features of Al2O3, Sr, Y, Yb and δEu in granite are similar to those of adakite and may be the result of the melting of the subducted oceanic crust. Therefore, the emergence of many copper deposits in the area should be related to the adakite.