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云南个旧地区花岗岩极其发育,且与锡成矿关系密切。其中个旧西区神仙水花岗岩体呈岩株状,岩性主要为碱长花岗岩和正长岩。岩石地球化学研究表明,神仙水花岗岩具有高硅、贫钙镁、富碱的特征;w(TFeO)/w(MgO)和w(Na2O+K2O)/w(Al2O3)比值高。富集大离子亲石元素Rb、Th、U、K、La、Nd和高场强元素Zr、Hf,亏损Ba、Sr、Ta、P、Ti。Eu负异常较强,轻稀土富集,重稀土相对亏损,稀土配分模式呈右倾海鸥型,岩石类型属于A型花岗岩。锆石LA-ICP-MS定年结果表明神仙水花岗岩体形成于81 Ma左右,相当于晚白垩世。根据区域地质和花岗岩地球化学特征,判断其形成于伸展构造环境。
Granite in Gejiu, Yunnan Province is extremely developed and closely related to tin mineralization. The Gexianshui granite body in Gejiu West District is in a rock-like shape with mainly lithic granite and syenite. The lithogeochemical study shows that the Shenxianshui granite is characterized by high silicon, poor calcium and alkali, and high ratio of w (TFeO) / w (MgO) and w (Na2O + K2O) / w (Al2O3) Enriched in large ion lithophile elements Rb, Th, U, K, La, Nd and high field elements Zr, Hf, depleted Ba, Sr, Ta, P, Ti. The Eu negative anomaly is strong, light rare earth is enriched, and heavy rare earth is relatively depleted. The REE pattern shows a right-angled seagull and the rock type belongs to A-type granite. The zircon LA-ICP-MS dating results show that the Shenxianshui granite was formed at 81 Ma, which is equivalent to Late Cretaceous. According to regional geology and granite geochemical characteristics, determine the formation of the extended tectonic environment.