Pentlandite is the dominant Ni-hosting ore mineral in most magmatic sulfide deposits and has conventionally been interpreted as being entirely generated by solid-state exsolution from the high-temperature monosulfide solid solution (MSS) (Fe,Ni)_1–xS. This process gives rise to the development of loops of pentlandite surrounding pyrrhotite grains. Recently it has been recognized that not all pentlandite forms by exsolution. Some may form as the result of peritectic reaction between early formed MSS and residual Ni-Cu–rich sulfide liquid during differentiation of the sulfide melt, such that at least some loop textures may be genuinely magmatic in origin. Testing this hypothesis involved microbeam X-ray fluorescence mapping to image pentlandite-pyrrhotite-chalcopyrite intergrowths from a range of different deposits. These deposits exemplify slowly cooled magmatic environments (Nova, Western Australia; Sudbury, Canada), globular ores from shallow-level intrusions (Norilsk, Siberia), extrusive komatiite-hosted ores from low and high metamorphic-grade terranes, and a number of other deposits. Our approach was complemented by laser ablation-inductively coupled plasma-mass spectrometry analysis of palladium in varying textural types of pentlandite within these deposits. Pentlandite forming coarse granular aggregates, together with loop-textured pentlandite where chalcopyrite also forms part of the loop framework, consistently has the highest Pd content compared with pentlandite clearly exsolved as lamellae from MSS or pyrrhotite. This is consistent with much of granular and loop pentlandite being formed by peritectic reaction between Pd-rich residual sulfide liquid and early crystallized MSS, rather than forming entirely by subsolidus grain boundary exsolution from MSS, as has hitherto been assumed. The wide range of Pd contents in pentlandite in individual samples reflects a continuum of processes between peritectic reaction and grain boundary exsolution. Textures in metamorphically recrystallized ores are distinctly different from loop-textured ores, implying that loop textures cannot be regenerated (except in special circumstances) by metamorphic recrystallization of original magmatic-textured ores. The presence of loop textures can therefore be taken as evidence of a lack of penetrative deformation and remobilization at submagmatic temperatures, a conclusion of particular significance to the interpretation of the Nova deposit as having formed synchronously with the peak of regional deformation at temperatures within the sulfide melting range.

中文翻译：

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岩浆镍铜硫化矿中闪锌矿-黄铜矿-硅镁铁矿环状结构的发生与成因

膨润土是大多数岩浆硫化物矿床中主要的含镍矿石矿物，通常被解释为完全由高温一硫化物固溶体（MSS）（Fe，Ni）_1–x的固态固溶产生。S.此过程引起围绕黄铁矿晶粒的五方辉石圈的发展。最近，人们已经认识到并非所有的五氧化二铁都可以通过解脱形成。硫化物熔体分化过程中，早期形成的MSS和残留的富Ni-Cu的硫化物液体之间发生包晶反应，可能形成某些晶核，因此至少某些回环织构可能是真正的岩浆。测试该假设涉及到微束X射线荧光映射，以成像来自一系列不同矿床的方铁矿-蛇纹石-黄铜矿共生体。这些矿床举例说明了缓慢冷却的岩浆环境（西澳大利亚州的诺瓦；加拿大的萨德伯里），浅层侵入体的球状矿石（西伯利亚的诺里尔斯克），低变质和高变质地层的膨润钾锰铁矿床矿石，以及许多其他例子。存款。我们的方法得到了这些矿床中不同质地类型的膨润土中钯的激光烧蚀-电感耦合等离子体质谱分析的补充。膨润土形成粗粒状聚集体，与环形纹理化的膨润土（黄铜矿也构成环形框架的一部分）相比，从MSS或黄铁矿中明显溶解为片状的膨润土，始终具有最高的Pd含量。这与迄今所假设的，由富Pd残留硫化物液体和早期结晶的MSS之间的包晶反应形成的许多颗粒状和环状的方铁矿一致，而不是完全由MSS的亚固相晶界析出形成。在单个样品中，方铁矿中Pd的含量范围很广，反映了包晶反应和晶界析出之间的连续过程。变质重结晶矿石中的纹理与环状纹理矿石明显不同，这意味着环状纹理不能通过原始岩浆构造矿石的变形重结晶而再生（特殊情况下除外）。因此，环状纹理的存在可以被视为在亚岩浆温度下缺乏穿透变形和移动的证据，这一结论对于解释新星矿床特别重要，因为该矿床与硫化物温度范围内的区域变形峰同步形成。熔化范围。变质重结晶矿石中的纹理与环状纹理矿石明显不同，这意味着环状纹理不能通过原始岩浆构造矿石的变形重结晶而再生（特殊情况下除外）。因此，环状纹理的存在可以被视为在亚岩浆温度下缺乏穿透变形和移动的证据，这一结论对于解释新星矿床特别重要，因为该矿床与硫化物温度范围内的区域变形峰同步形成。熔化范围。变质重结晶矿石中的纹理与环状纹理矿石明显不同，这意味着环状纹理不能通过原始岩浆构造矿石的变形重结晶而再生（特殊情况下除外）。因此，环状纹理的存在可以被视为在亚岩浆温度下缺乏穿透变形和移动的证据，这一结论对于解释新星矿床特别重要，因为该矿床与硫化物温度范围内的区域变形峰同步形成。熔化范围。