Xinyue Xu, W. Bain, F. Tornos, J. Hanchar, Hector M. Lamadrid, Bernd Lehmann, Xiaochun Xu, Jeffrey A. Steadman, Ralph S. Bottrill, Majid Soleymani, A. Rajabi, Peng Li, Xuehai Tan, Shihong Xu, A. Locock, M. Steele‐MacInnis
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引用次数: 0
Abstract
The origins of magnetite-apatite deposits are controversial, and the crux of the debate is what types of fluids form these rocks. We present evidence from 20 magnetite-apatite deposits worldwide showing ubiquitous involvement of molten salts. The studied deposits are distributed globally, from various tectonic settings, and from Precambrian to Quaternary in age. In every case, water-poor polycrystalline melt inclusions in ore-stage minerals are dominated by sulfate, chloride, and carbonate components plus variable proportions of calc-silicates, phosphates, and iron ± titanium oxides that re-melt between 285 °C and 1100 °C. These fluids are very different from what is generally expected in most geologic settings, but their ubiquitous presence in magnetite-apatite rocks indicates that molten salts are widespread and essential to the formation of these deposits.
磁铁矿-磷灰石矿床的起源颇具争议，争论的焦点在于形成这些岩石的流体类型。我们展示了来自全球 20 个磁铁矿-磷灰石矿床的证据，表明熔盐的参与无处不在。所研究的矿床分布在全球各地，来自不同的构造环境，年代从前寒武纪到第四纪。在每一种情况下，矿石阶段矿物中的贫水多晶熔融包裹体都以硫酸盐、氯化物和碳酸盐成分为主，外加不同比例的钙硅酸盐、磷酸盐和铁±钛氧化物，在 285 °C 至 1100 °C 之间重新熔融。这些流体与大多数地质环境中的预期流体大相径庭，但它们在磁铁矿-磷灰石岩石中的普遍存在表明，熔盐在这些矿床的形成过程中非常普遍和重要。
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