芬兰北部克维特斯塔镍-铜-铂族元素矿床地质特征及矿床成因

    Geological characteristics and genesis of the Kevitsa Ni-Cu-PGE deposit, northern Finland

    • 摘要: 位于芬兰北部中拉普兰绿岩带的克维特斯塔(Kevitsa)镍-铜-铂族元素矿床是世界上主要的岩浆镍-铜硫化物矿床之一。该矿床储量大,含丰富的镍-铜硫化物和铂族元素。对矿床产出环境、地质特征、矿床成因等进行了总结,结果表明:矿体主要赋存于克维特斯塔基性—超基性层状侵入体的超基性单元中。主要矿石类型为普通型和镍-铂族元素型2种,其中镍-铂族元素型矿石内橄榄石具极高的Ni含量。主要矿石矿物为磁黄铁矿、镍黄铁矿、黄铜矿、黄铁矿、针硫镍矿、红砷镍矿、砷镍矿、辉砷镍矿等,绝大部分铂族矿物包含在硅酸盐中和附着在硫化物颗粒边界。Re-Os、Sm-Nd、Sr及S同位素特征显示成矿岩浆为幔源,但受到地壳物质的混染作用。Pb同位素年代学结果表明克维特斯塔侵入体形成于古元古代。

       

      Abstract: Located in the Central Lapland greenstone belt of northern Finland, the Kevitsa Ni-Cu-PGE deposit is one of the major magmatic Ni-Cu sulfide deposits in the world. The deposit has abundant reserves and is rich in Ni-Cu sulfide and PGE. This paper summarizes the environment, geological characteristics, ore genesis and other aspects of the ore deposit. The orebodies are mainly hosted in ultramafic unit in the Kevitsa mafic-ultramafic layered intrusions; the main ore types are divided into two types, i.e., common type and Ni-PGE type; the olivines in Ni-PGE type have extremely high Ni content; the main ore minerals include pyrrhotite, pentlandite, chalcopyrite, pyrite, millerite, niccolite, chloanthite and gersdorffite, with most of the platinum group minerals contained in the silicate or attached to the boundary of sulfide particles; Re-Os, Sm-Nd, Sr and S isotopic characteristics indicate that mineralized magma was derived from the mantle, but the magma was contaminated by crustal substances; geochronologic analysis indicates that Kevitsa intrusion was formed in the Paleoproterozoic.

       

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