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太古代各种岩石类型和矿化的大多数硫化物显示,其硫同位素值(δ~(34)S)接近0％。这是由于通常缺乏适合于为同位素分馏所必需的氧化-还原反应的环境造成的。然而,太古代金矿化的一些重要的矿产地确实显示有明显的δ~(34)S变化。具异常同位素组成的这种矿产地之一是赫姆洛金矿床。矿石中黄铁矿的δ~(34)S值一般<-6‰至最小值-17.5‰。该黄铁矿的同位素组成与Au的含量有关,这说明它们在成因上是有关的。 硫同位素数据表明,赫姆洛热液体系中的硫的化合物经历了氧化还原反应;硫酸盐在Au矿化之前就已存在了。该硫酸盐可能是外生成因的:来源于隔离盆地,也可能是内生成因的:来源于岩浆热液流体。赫姆洛矿床的其他特征,诸如富集Sb、Tl和Hg,也可解释如下:矿石在中等氧化条件下沉淀。 特征的δ~(34)S值也在下述地点的黄铁矿中观测到:赫姆洛西面30km的赫伦贝Au矿化;赫姆洛以西约21至27km及近似走向方向的重晶石层。这些矿产地也是含硫酸盐热液体系,就这一点而论,这些矿产地给出的有关赫姆洛金矿化异常环境的信息是不明确的。既然硫同位素对氧化环境敏感,那么硫同位素可以用来识别这类金矿化特征的水热活动,也可用来勘探太古代地体中有硫酸盐堆积的其他异常区。
Most of the Archean rock types and most of the sulphides mineralized show that their sulfur isotope values (δ ~ (34) S) are close to 0%. This is due to the general lack of an environment suitable for the oxidation-reduction reaction necessary for isotopic fractionation. However, some important mineral deposits of the Archean gold mineralization did show a clear δ ~ (34) S variation. One of such mineral deposits with anomalous isotopic composition is the Helmut Gold Deposit. The δ ~ (34) S value of pyrite in ore is generally <-6 ‰ to the minimum value of -17.5 ‰. The isotopic composition of the pyrite is related to the Au content, suggesting that they are genetically related. Sulfur isotope data show that sulfur compounds in the Helmholic hydrothermal system undergo a redox reaction; sulfates are present prior to Au mineralization. The sulphate may be exogenous: originating in the isolated basin, or endogenously: from magmatic hydrothermal fluids. Other features of the Hemlo deposit, such as enrichment of Sb, Tl and Hg, may also be explained as follows: Ores precipitate under moderate oxidation conditions. The δ ~ (34) S values of the features were also observed in pyrite in the following locations: Herrenberg Au mineralization 30 km west of Hemluth, 21 to 27 km west of Hemmoullo and an approximate strike- Stone layer. In this regard, these mineral deposits are also sulfate-bearing hydrothermal systems. The information given by these mineral sites on the abnormal environment of the Helmut alluvial mineralization is not clear. Since sulfur isotopes are sensitive to oxidative environments, sulfur isotopes can be used to identify hydrothermal activity of such gold mineralization features and to explore other anomalous zones of sulphate accumulation in the Archean landmass.