The role of emulsions in magmatic sulfide deposits

硅酸盐与硫化物熔体之间的液体不相容性是岩浆硫化物矿床形成的重要条件。这些是世界上最有价值的金属资源之一，形成Ni-Cu-Co-铂族元素（PGE）矿床（例如，萨德伯里和诺里尔斯克;地球上两个最大的镍和铜硫化物富集区以及第二和第三大铂族元素富集区; Naldrett，2011年）。令人惊讶的是，到目前为止，关于液体不可渗透性的质地证据，冷冻乳剂，还没有详细研究，这就是博士候选人的这个提案的主题。将讨论三个目标：（1）将从结构和化学上研究乳状液结构的可变性（例如不同的球状乳状液和相互连接的乳状液），并与类似结构（例如网状结构的硫化物、碎屑碎片）和乳状液的寄主岩石进行比较，以研究硫化物的侵位历史和在侵位过程中乳状液的形成。用于这一目的的样品来自世界范围内各种各样的岩浆硫化物矿点。(2)来自Nova存款（澳大利亚）的乳状液通常与硫化物嵌入的大硅酸盐晶体有关。假设这些晶体是由于变化的条件（如冷却）而在乳液中生长的。在生长之后，当两种熔体分离时（由于熔体的缓慢移动），乳液的硅酸盐熔体部分漂浮起来，留下硫化物中的晶体。为了测试这一点，晶体将在质地和化学上与乡村岩石进行比较。(3)一种迄今为止尚未描述的乳液结构包括在包岑（德国，索拉）附近的硫化物豆荚中的乳液的硅酸盐液滴上的氧化物-磷灰石涂层。假设是，这种涂层代表硅酸盐和硫化物熔体之间的第三种熔体，并作为乳化剂，这在任何地质背景下都没有描述过。硫化物和硅酸盐熔体之间的这种物理屏障将阻止它们之间的元素的“常规”分配，因此，痕量元素（除了结构观察）将被用来研究和解释这种新的乳胶结构。所有这三个目标将有助于更好地了解岩浆硫化物矿床的形成和侵位过程。这将为其他研究人员对乳状液进行分类和鉴别，并将其与不同过程中形成的相似纹理区分开来奠定基础。在野外识别乳状液有助于岩浆硫化物矿床的勘探，将其从乳状液（通常在陡峭侵入接触面上的次经济硫化物中发现）引向主矿体。

Liquid immiscibility between silicate and sulfide melt is an important prerequisite to form magmatic sulfide deposits. These are amongst the most valuable metal resources in the world, forming Ni-Cu-Co- platinum group element (PGE) deposits (e.g., Sudbury and Noril’sk; the two largest accumulations of Ni- and Cu-sulfides and the second and third largest PGE enrichments on Earth; Naldrett, 2011). Surprisingly, the textural evidence for liquid immiscibility, frozen emulsions, are not studied in detail so far and this is the topic of this proposal for a PhD candidate. Three objectives will be addressed:(1) The variability of emulsion textures (e.g. different spheroidal and interconnected emulsions) will be texturally and chemically studied and compared to similar textures (e.g. net-textured sulfides, clast fragmentation) and the host rocks of the emulsions to study the emplacement history of sulfides and emulsion formation in the course of that emplacement. The samples for this objective come from a large variety of magmatic sulfide occurrences worldwide.(2) Emulsions from the Nova deposit (Australia) are typically associated with large silicate crystals embedded by sulfides. The hypothesis is that these crystals grew within the emulsion due to changing conditions, such as cooling. After growth, the silicate melt portion of the emulsion floated up when both melts separated (due to slowing movement of the melts), leaving the crystals in the sulfides behind. To test this, the crystals will be texturally and chemically compared to the country rocks.(3) A hitherto undescribed emulsion texture comprises oxide-apatite coatings on silicate droplets of an emulsion from sulfide pods near Bautzen (Sora, Germany). The hypothesis is that this coating represents a third melt between silicate and sulfide melt and acted as an emulsifier, which has not been described before in any geological context. This physical barrier between the sulfide and the silicate melt would prevent a "conventional" partitioning of elements between them and, therefore, trace elements (besides textural observations) will be used to study and interpret this new emulsion texture.All three objectives will help to better understand the processes involved in the formation and emplacement of magmatic sulfide deposits. It will create a foundation for other researchers to classify and discriminate emulsions and to distinguish them from similar textures, which formed in different processes. The identification of emulsions in the field can help exploration for magmatic sulfide deposits in directing them from the emulsion, which is usually found in sub-economic sulfides on steep intrusive contacts, towards the main orebody.