云南马厂箐金矿区煌斑岩地球化学及成因探讨

STUDY ON GEOCHEMISTRY AND GENESIS OF LAMPROPHYRES IN MACHANGQING GOLD DEPOSITS AREA, YUNNAN PROVINCE

广泛分布于云南马厂箐金矿区煌斑岩主要为云煌岩，主要元素表明为碱性系列、钾质钙碱性煌斑岩；过渡元素分配模式为馒源岩石的“Ｗ”型、不相容元素分配模式为大离子亲石元素和高场强元素富集的“骆峰”型、稀土元素分配模式为“右倾”的轻稀土富集型、以及模拟计算均表明，该区煌斑岩为交代富集地幔部分熔融（熔融程度约为１２％）的产物。新鲜、蚀变、矿化煌征岩Ａｎ，ＣＯ２，Ｆｅ＿２Ｏ＿３，ＦｅＯ等的含量及变化规律，暗示其在金矿成矿过程中可能主要起“地球化学障”的作用。

Lamprophyres, which widely disperse over Machangqing gold deposits ares, Yunnan Province,are temporally and sPatially related to Au mineralization manily are minettes and their major mineral assemblage is clinopyroxene+mica+feldspar. Major elements show that lamprophyres are alklicseries and potassic cala-alkaline lamprophyres. Chondrite-normalized transition elementpattern of 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. All the characteristics as noted above and model calculation suggest that the source of the lamprophyres is imcompatible element-enriched metasomatic mantle. The contents of Au,Co2, Fe2O3 and FeO etc. and FeO etc. and their varied laws in fresh (weak alterated), alterated and mineralized lamprophyres respectively indicates that they Play a role as geochemical barrier. Major structures in orefield are advantigeous to intrusion of lamprophyric magmas and mineralization of hy drothermal solution.