The characteristics of Au partitioning in a multiphase, multicomponent hydrothermal system at 450 °C and 1 kbar pressure were obtained using experimental and computational physicochemical modelling and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. Sphalerite and magnetite contained 0.1–0.16 ± 0.02 µg/g Au and coexisted with galena and bornite which contained up to 73 ± 5 and 42 ± 10 µg/g Au, respectively. Bornite and chalcopyrite were the most effective Au scavengers with cocrystallization coefficients Au/Fe and Au/Cu in mineral-fluid system n–n × 10⁻². Sphalerite and magnetite were the weakest Au absorbers, although Fe impurity in sphalerite facilitated Au uptake. Using the phase composition correlation principle, Au solubility in minerals was estimated (µg/g Au): low-Fe sphalerite = 0.7, high-Fe sphalerite = 5, magnetite = 1, pyrite = 3, pyrite-Mn = 7, pyrite-Cu = 10, pyrrhotite = 21, chalcopyrite = 110, bornite = 140 and galena = 240. The sequence reflected increasing metallicity of chemical bonds. Gold segregation occurred at crystal defects, and on surfaces, and influenced Au distribution due to its segregation at crystal interblock boundaries enriched in Cu-containing submicron phases. The LA-ICP-MS analysis of bulk and surficial gold admixtures revealed elevated Au content in surficial crystal layers, especially for bornite and galena, indicating the presence of a superficial nonautonomous phase (NAP) and dualism in the distribution of gold. Thermodynamic calculations showed that changes in experimental conditions, primarily in sulfur regime, increased the content of the main gold species ( and ) and decreased the content of , the prevailing form of iron in the fluid phase. The elevation of S₂ and H₂S fugacity affected Au partitioning and cocrystallization coefficients. Using Au content in pyrite, chalcopyrite, magnetite and bornite from volcanic-sedimentary, skarn-hosted and magmatic-hydrothermal sulfide deposits, the ranges of metal ratios in fluids were estimated: Au/Fe = n × 10⁻⁴-n × 10⁻⁷ and Au/Cu = n × 10⁻⁴-n × 10⁻⁶. Pyrite and magnetite were crystallized from solutions enriched in Au compared to chalcopyrite and bornite. The presence of NAP, and associated dualism in distribution coefficients, strongly influenced Au partitioning, but this effect does not fully explain the high gold fractionation into mineral precipitates in low-temperature geothermal systems.

中文翻译：

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模型多相矿物水热流体系统中的金分配：分布系数，形态和偏析

使用实验和计算物理化学模型以及激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）分析，获得了在450°C和1 kbar压力下在多相多组分水热系统中Au的分配特征。闪锌矿和磁铁矿的金含量为0.1–0.16±0.02 µg / g，与方铅矿和堇青石共存，方铅矿和斑铁矿的含量分别高达73±5和42±10 µg / g。在矿物-流体系统n – n ×10 ^-2中，硼铁矿和黄铜矿是最有效的金清除剂，共结晶系数为Au / Fe和Au / Cu。闪锌矿和磁铁矿是最弱的Au吸收剂，尽管闪锌矿中的Fe杂质促进了Au的吸收。使用相组成相关原理，可估算出Au在矿物中的溶解度（µg / g Au）：低铁闪锌矿= 0.7，高铁闪锌矿= 5，磁铁矿= 1，黄铁矿= 3，黄铁矿Mn = 7，黄铁矿- Cu = 10，黄铁矿= 21，黄铜矿= 110，斑铁矿= 140，方铅矿=240。该序列反映了化学键的金属性增加。金的偏析发生在晶体缺陷处和表面，并且由于金在富含铜的亚微米相中富集的晶体块间边界处的偏析而影响了金的分布。对大量和表面金混合物的LA-ICP-MS分析表明，表面晶体层中的Au含量升高，特别是对于褐铁矿和方铅矿，表明在金的分布中存在表面非自治相（NAP）和二元论。热力学计算表明，实验条件的变化（主要是在硫状态下）增加了主要金类（和）的含量，并降低了液相中铁的主要形式的含量。S的海拔₂和H ₂ S逸度影响Au的分配和共结晶系数。从火山沉积，夕托管和岩浆热液硫化物矿床使用在黄铁矿，黄铜矿，磁铁矿Au含量和斑铜矿，的金属比率在流体范围估计：金/铁= Ñ ×10 ^-4 -n ×10 ^{- 7}和Au / Cu = n×10 ^-4 -n×10 ^-6。与黄铜矿和堇青石相比，硫铁矿和磁铁矿从富含金的溶液中结晶。NAP的存在以及分配系数中的相关二元性极大地影响了Au的分配，但是这种效果不能完全解释在低温地热系统中高金分馏成矿物沉淀的情况。