Multi-stage sulfide evolution of the Moran Ni sulfide ore, Kambalda, Western Australia: insights into the dynamics of ore forming processes of komatiite-hosted deposits
Multi-stage sulfide evolution of the Moran Ni sulfide ore, Kambalda, Western Australia: insights into the dynamics of ore forming processes of komatiite-hosted deposits
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DOI：
10.1007/s00126-021-01060-5
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发表时间：
2021-10
影响因子：
4.8
通讯作者：
S. Staude;M. Oelze;G. Markl
中科院分区：
文献类型：
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作者：
S. Staude;M. Oelze;G. Markl
澳大利亚坎巴尔达的莫兰科马提岩型硫化镍存款是坎巴尔达保存较好的矿体之一。其地球化学特征可用于研究硫化物成矿作用的演化。矿体有几个部分，包括一个侧翼部分，块状硫化物形成相对较早，中心部分在40米深的侵蚀海湾代表了后来一代的块状和网状结构的硫化物。深水湾内的基底块状硫化物的亲铜元素（Ni、PGE、Au、Te、As、Bi）含量有系统的变化。一硫化物固溶体（MSS）中相容元素在矿体边缘的浓度最高（高达4.3 ppm Ir + Os + Ru + Rh），而不相容元素则在中心最高（高达11.2 ppm Pt + Pd + Au）。元素分布的这种差异是由硫化物熔体从边缘向中心的分步结晶来解释的。为了解释残余分馏熔体的垂直运动，提出了一个新的硫化物结晶模型。在MSS和硫化物熔体之间形成了一个含有不相容元素的低粘度边界层。该熔体随着结晶前沿向硫化物熔体池的中心传播。镍黄铁矿（如钴）和复合Co和Bi轴承砷碲化物颗粒的微量元素的变化表明，在结晶的最后阶段，形成不混溶的Co-As-Te-Bi熔体。
The Moran komatiite-hosted Ni sulfide deposit at Kambalda (Australia) is one of the better preserved orebodies at Kambalda. Its geochemical signature is used to investigate the evolution of the sulfide mineralization. The orebody has several parts, including a flanking segment where massive sulfides formed relatively early and a central portion in a 40-m-deep erosional embayment representing a later generation of massive and net-textured sulfides. Basal massive sulfides within the deep embayment vary systematically in their chalcophile element contents (Ni, PGE, Au, Te, As, Bi). Elements compatible in monosulfide solid solution (MSS) exhibit the highest concentration at the edge of the orebody (up to 4.3 ppm Ir + Os + Ru + Rh), whereas incompatible elements are most concentrated in the centre (up to 11.2 ppm Pt + Pd + Au). This difference in element distributions is explained by fractional crystallization of sulfide melt from the edge towards the centre. To explain the vertical movement of the residual fractionated melt, a new model of sulfide crystallization is proposed. A low-viscosity boundary layer containing incompatible elements is formed between MSS and sulfide melt. This melt propagates with the crystallization front towards the centre of the sulfide melt pool. Trace element variations in pentlandite (e.g. Co) and composite Co- and Bi-bearing arsenide-telluride grains suggest that during the final stages of crystallization, an immiscible Co-As-Te-Bi melt is formed.