滇西富碱斑岩型矿床岩体和矿脉同位素地球化学研究

选取马厂箐铜钼金矿、金厂箐金矿、北衙铅金矿和姚安铅银金矿四个典型的富碱斑岩型多金属矿床，对岩体和矿脉的铅、硅、氢、氧、硫、碳及氦、氩同位素分析。结果表明，富碱岩浆和富硅成矿流体的最初和主要铅源均来自地幔，但混染了部分地壳或地层铅；富碱岩浆起源于地幔交代作用形成的富集地幔源区，而富硅成矿流体则具有原始地幔流体性质，前者的硅同位素组成表现为经历强烈动力分馏的高正值；后者则为几乎未经动力分馏的低负值。综合研究表明，该类矿床的成矿作用是在富碱岩浆的成岩过程中，伴随富硅成矿流体对岩体和地层围岩的(自)交代蚀变作用，并与岩石一定程度混染而实现的。因此，富硅成矿流体作用实质上是地幔流体交代作用在地壳内成矿作用中的延续。

Isotopic Geochemistry of Rock Mass and Ore-vein from Alkali-rich Porphyry Type Deposits in Western Yunnan, China

In this paper, four typical alkali-rich porphyry type deposits are studied by means of lead,silicon,hydrogen,oxygen,sulphur,carbon,helium and argon isotope from rockbodies and ore-veins in deposits, and the following conclusions could be obtained. The initial lead and most lead source of alkali-rich magma and silicon-rich mineralizing fluid were derived from mantle, yet it is inevitably that mantle lead mixed with some lead from crust or strata; The alkali-rich magma derived from a source in enriched mantle to be formed by mantle metasomatism is characterized by high positive number of silicon isotope composition experienced intense dynamic fractionation. But the silicon-rich mineralizing fluid, which has the nature of primary mantle, is characterized by low negative number of silicon isotope composition without dynamic fractionation. To sum up, we beliere that the mineralization was completed by silicon-rich ore-fluid auto-metasomatism to country rocks (including alkali-rich porphyry and stratum rock), and by mixing with crust rock to varying extent, during crystallization of alkali-rich magma. The silicon-rich mineralizing fluid process is a continuation of mineralization led by the mantle fluid metasomatism in crust.