云南老王寨金矿区煌斑岩的地球化学

GEOCHEMISTRY OF LAMPROPHYRES IN LAOWANGNGZHAI GOLD DEPOSIT,YUNNAN PROVINCE

报道了云南老王寨金矿区与金矿化时空密切共生的煌斑岩的地球化学资料。主要元素研究表明，研究区煌斑岩属钾质－富钾质钙碱性煌斑岩；过渡元素分配模式为典型幔源岩石的“Ｗ”型，岩石富集大离子亲石元素、高场强元素、稀土元素以及相对高８７Ｓｒ／８６Ｓｒ、低１４３Ｎｄ／１４４Ｎｄ比值等特征都暗示，该区煌斑岩源于交代富集地幔；地质发展史，不相容元素分配模式，Ｓｒ、Ｎｄ同位素组成及有关模拟计算表明，俯冲进入地幔楔的地壳物质脱水形成的流体是引起该区地幔交代作用的主要因素。

Geochemical data of lamprophyres which are temporally and spatially related to Au mineralization in Laowangzhai gold deposit, Yunnan Province are reported.Major elements show that lamprophyres in the orefield are alkalic series and potassic calc-alkaline lamprophyres. Chondrite-normalized transition element pattern of the lamprophyres is'W'type which suggests that the rocks are mantle-derived. The lamprophyres are enriched in large iron lithophile elements,high field strength elements and rare earth elements, and have high87Sr/86Sr but low143Nd/144Nd ratio. All these characteristics and model calculation suggest that the source of the lamprophyres is incompatible element-enriched metasomatic mantle。