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本文从地球化学硫同位素组成角度出发,对我国西南硫矿带层状黄铁矿床的成矿地质条件及矿床成因进行探讨,总结成矿规律,指出找矿方向。 根据川滇黔交界地区10余县30个矿产地采集的63件黄铁矿单矿物硫同位素样品测试结果:硫同位素值变化范围宽,δS~(34)最重+27.3‰,最轻-34.9‰,一般值+15—-25‰,算术平均值-5.4‰。硫同位素组成图案呈波浪状弥散分布,显示着沉积矿床特征。 区域资料表明,黄铁矿的生成与峨嵋山期火山活动息息相关,含矿岩石由火山岩—火山碎屑岩—沉积火山碎屑岩—火山碎屑沉积岩—沉积岩呈自西而东的规律性递变——环火山机体作带状展布,由西向东矿层厚度减小,矿体品位依次降低,TiO_2与TS含量呈正相关关系,钴镍比值由大变小(平均由1—0.1),显然与物源供给存在着密切的成生联系。 综上认为,我国西南硫矿带的矿床成因应属与峨嵋山玄武岩有关的热液—沉积矿床。地质资料和硫同位素资料阐明,从玄武岩浆中分馏出来的含矿挥发组分,经海底热液转移到海盆地中,所以说生成黄铁矿的硫主要来自海水硫酸盐,而铁质主要是玄武岩与海水反应时淋滤出来的.矿床硫同位素组成在空间上和时间上的变化与当时沉积环境的差异和演变有关。 该硫矿带形成一系列热液—沉积黄铁矿床,在西部火山作用相对显著,至东部沉积
Based on the composition of geochemical sulfur isotopes, this paper discusses the metallogenic geological conditions and the genesis of the bedded pyrite deposits in the southwestern sulfur deposit belt in China, summarizes the metallogenic regularity and points out the prospecting direction. According to the single-mineral sulfur isotope samples of 63 pyrite samples collected from 30 mineral deposits in more than 10 counties in the border areas of Sichuan, Yunnan and Guizhou, the results show that the sulfur isotope value has a wide range of variation, with the highest value of δS ~ (34) being + 27.3 ‰ and the lightest of -34.9 ‰, the general value of +15--25 ‰, arithmetic average -5.4 ‰. Sulfur isotope composition patterns were wavy diffuse distribution, showing the characteristics of sedimentary deposits. The regional data show that the formation of pyrite is closely related to the volcanic activity of Emei period. The ore-bearing rocks are volcanic-pyroclastic-sedimentary pyroclastic-volcaniclastic sedimentary-sedimentary rock and are regularly changing from west to east - ring volcanic body as a belt-like distribution, from the west to the East seam thickness decreases, followed by ore grade lower, TiO 2 and TS content was positively correlated, cobalt-nickel ratio from large to small (an average of 1-0.1), apparently with There is a close relationship between supply of provenance. In conclusion, the genesis of the deposits in the southwestern sulfur deposit belt in China should belong to hydrothermal-sedimentary deposits related to the Basalt of Emei Mountain. Geological data and sulfur isotope data indicate that the ore-bearing volatile components fractionated from basaltic magma are migrated into the basin by seafloor hydrothermal fluids, so the sulfur that generates pyrite is mainly derived from seawater sulfate, whereas the iron is mainly The basalts are leached when they react with the seawater.The spatial and temporal changes of the sulfur isotopic composition of the deposit are related to the differences and evolution of the sedimentary environment at that time. The sulphide belt forms a series of hydrothermal-sedimentary pyrite deposits with relatively significant volcanism in the west and sediments to the east