The ~ 487 Ma Ming volcanogenic massive sulfide (VMS) deposit consists of four subparallel, elongated, semi-massive to massive sulfides lenses (the 1807, 1806, Ming North, and Ming South zones) hosted in rhyodacite of the Rambler Rhyolite formation, Newfoundland Appalachians. A discordant Cu-rich Lower Footwall zone underlies the semi-massive to massive sulfide lenses. Alteration associated with mineralization can be divided into nine facies that formed in three paragenetic stages: (1) weak quartz–calcite ± spessartine, quartz–sericite, and quartz–sericite–chlorite alteration (stage 1); (2) quartz–chlorite, quartz–chlorite–sulfide, and quartz–chlorite–sericite assemblages (stage 2); and (3) quartz–sericite–sulfide and localized Mn-rich carbonate assemblages (stage 3). A thin syngenetic silica-rich layer immediately overlies part of the VMS deposit and likely formed during the early stages. The volcanic architecture and synvolcanic faults controlled the lateral distribution of extrusive rocks and hydrothermal alteration. Precipitation of the high temperature, discordant to semi-conformable Cu-rich chloritic assemblages (stockwork), was laterally restricted to one of these synvolcanic faults and the transition from coherent- to volcaniclastic-dominated lithofacies. Lower temperature, sericitic assemblages (stages 1 and 3) are controlled by the distribution of volcaniclastic rocks and generally form the immediate footwall to the semi-massive to massive sulfide lenses. Lithogeochemical mass balance calculations illustrate the alteration minerals and mineralization: chlorite-rich assemblages—gains in SiO 2 , Fe 2 O 3 t, MgO, Cr, Ni, and Cu and losses in Na 2 O, MnO, and CaO and sericite-rich assemblages—gains in K 2 O, Zn, and Ag and losses in MnO, MgO, CaO, Na 2 O, and Y. Calcium- and magnesium-rich alteration assemblages are restricted to the northwest fringe of the deposit, distal to the main chloritic and sericitic alteration, and have elemental gains in P 2 O 5 , Y, and losses in K 2 O. The late stage 3 quartz–sericite–sulfide assemblage overprints most assemblages, hosts sphalerite–galena–sulfosalt–Ag–Au-rich veins, and is spatially associated with coherent volcanic rocks. The less permeable nature of these rocks is interpreted to have acted as a physical barrier for ascending metal-rich hydrothermal fluids. Results from the detailed reconstruction of the hydrothermal architecture and paragenetic evolution of the Ming deposit suggest that precious metals were introduced during the waning stage of the hydrothermal system, associated with decreases in temperature and pH of the hydrothermal fluids.

中文翻译：

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与纽芬兰阿巴拉契亚山脉明 VMS 矿床相关的海底热液系统的演化及其对贱金属和贵金属分布的控制

~ 487 Ma Ming 火山成因块状硫化物 (VMS) 矿床由四个亚平行、细长、半块状至块状硫化物透镜体（1807、1806、Ming North 和 Ming South 区域）组成，位于纽芬兰 Rambler 流纹岩地层的流纹岩阿巴拉契亚人。在半块状到块状硫化物透镜体的下方是一个不协调的富含铜的下下盘带。与成矿相关的蚀变可分为九个相，形成于三个共生阶段：（1）弱石英-方解石-锰铝榴石、石英-绢云母和石英-绢云母-绿泥石蚀变（阶段 1）；(2) 石英-绿泥石、石英-绿泥石-硫化物和石英-绿泥石-绢云母组合（阶段 2）；(3) 石英-绢云母-硫化物和局部富锰碳酸盐组合（第 3 阶段）。一个薄的同生富二氧化硅层立即覆盖在 VMS 矿床的一部分上，很可能是在早期阶段形成的。火山构造和同火山断层控制了喷出岩和热液蚀变的横向分布。高温的降水与半整合富铜绿泥石组合（网状结构）不一致，被横向限制在这些同火山断层之一以及从相干岩相到火山碎屑岩相的转变。较低温度的绢云母组合（阶段 1 和 3）受火山碎屑岩的分布控制，通常形成半块状到块状硫化物透镜体的直接下盘。岩石地球化学质量平衡计算说明了蚀变矿物和矿化：富含绿泥石的组合 - SiO 2 中的增益，Fe 2 O 3 t、MgO、Cr、Ni 和 Cu 以及 Na 2 O、MnO 和 CaO 中的损失以及富含绢云母的组合——K 2 O、Zn 和 Ag 中的增加以及 MnO、MgO、CaO、 Na 2 O 和 Y。富含钙和镁的蚀变组合仅限于矿床的西北边缘，在主要绿泥石和绢云母蚀变的远端，P 2 O 5 、Y 元素增加，K 丢失2 O. 后期 3 石英-绢云母-硫化物组合叠印了大多数组合，拥有富含闪锌矿-方铅矿-硫盐-Ag-Au 的矿脉，并且在空间上与连贯的火山岩有关。这些岩石渗透性较低的性质被解释为对上升的富含金属的热液流体起到了物理屏障的作用。