金川含铜镍超基性岩体的岩浆包裹体特征及其地质意义

THE CHARACTERISTICS AND GEOLOGICAL SIGNIFICANCE MAGMATIC INCLUSIONS IN THE JINCHUAN COPPER-NICKELBEARING ULTRABASIC INTRUSION, GANSU PROVINCE

作者首次于金川含铜镍超基性岩体中发现了岩浆包裹体。本文系统研究了岩浆包裹体特征,阐述了包裹体中橄榄石、斜方辉石、单斜辉石、铬尖晶石等晶相子矿物的化学成分以及F_2、Cl_2,CH_4、H_2S、H_2O、SO_2、CO_2等气相挥发组份。测温结果表明,原生岩浆包裹体的均一化温度介于950—1100℃。各造岩矿物中原生岩浆包裹体的发现,证明金川岩体为岩浆成因。包裹体中不混熔现象的发现,证明各类岩石和矿体是铁质超基性含矿熔浆在液态就地分熔成不同成分的熔体,并在不同的物理化学条件下结晶而成。这些研究对认识成岩成矿的物化条件和成因具有重要意义。

Magmatic inclusions were first found in the Jinchuan copper-nickel-bearing ultrabasic intrusion by the authors. The characteristics of magmatic inclusions are systematically studied. The chemical compositions of such crystal-phase daughter minerals olivine, orthopyroxene, clinopyroxene and accessory chrome-spinel and gas-phase volatile components such as F_2, C_(12), CH_4, H_2S, H_2O, SO_2, and CO_2 were measured. The homogenization temperature of magmatic inclusions is in the range of 950—1100℃. The discovery of primary magmatic inclusions in rock-forming minerals suggests a magmatic genesis for the Jinchuan intrusion. Immiscibity in magmatic inclu sions shows that various types of rock and ore were formed by crystallization of melts of different compositions resulting from in-situ liquid unmixing of ferruginous ultrabasic ore-bearing molten magmaas under different physical-chemical conditions. Thes studies are of major significance to the recognition of physicalchemical conditions of rock and ore formation and geneses of rock and ore.