Mineralized Magmatic Hydrothermal Systems

矿化岩浆热液系统

• 批准号: RGPIN-2019-07304
• 负责人: Lentz, David
• 金额: $ 1.82万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680892
• 关键词: Mineralized; Magmatic; Hydrothermal; Systems

This specific research application focuses on complex infiltrative metasomatic reaction systems, which indirectly relates to the spectrum from magmatic volatile evolution through to the distal precipitation of associated metal complexes; this is an extension of my research on skarn systems that has had several key impacts, which most notably are: 1) some important phase relations have been highlighted in mixed volatile, infiltrative contact metasomatic systems, 2) permeability evolution during solution-host rock reaction coupled with the analysis of physio-chemical reactions, and 3) the provocative petrogenetic interpretation of some derivative igneous rocks, their gases, and eruptive/brecciation style has a wide range of implications. These contributions are all interrelated as the complex feedback mechanisms (i.e., CO2 back infiltration from decarbonation fronts) affect fluid-mineral-melt phase relations (i.e., lowering P(H2O)) that affect gas speciation, vapour saturation, and critical behaviour, metal partitioning, i.e., Fe, Cu, Au, W, Mo, etc. through to actual volcanic processes. This includes differential degassing at various pressures that can result in hypersaline fluids to salt or carbonate melts (some Fe-rich salt to carbonate melts) that may possibly explain some problematic genetic aspects of certain skarn-related deposit systems, i.e., magnetite-rich IOA & IOCG systems. Recent research of fluid reaction aspects that relate to silica activity relations in low to high T hypersaline systems shows silica activities vary widely, affecting proportion of calc-silicates formed with mineralization, which is critical to interpretation of many of these controversial systems. Mass-balance analysis of various infiltrative skarns compliments this research, although is definitely challenging; detailing the proportion of material added to and (or) removed from metasomatic systems helps to constrains the degree of fluid-rock reaction associated with infiltrative reaction metasomatic systems, the elemental mobility (fluid-rock ratios) observed, and the mechanisms responsible for these endo- and exo-contact reaction zones. The most provocative aspects reexamine the two end-member volatile fluxing and limestone-magma reactions during silicate magma interaction that are related to high-T magmatic skarn processes. These volatile fluxing to syntectic processes require a better understanding of complex high-T, skarn-forming processes, including mixed volatile infiltrative decarbonation equilibria and carbonate solubilities versus carbonate fluxing relations, open versus closed system reactions governing differential degassing of carbonated silicate, carbonate immiscibility, as well as their emplacement processes, including explosive pyroclastic volcanism; degassing significantly changes the P?V enhancing explosively of these systems. Rayleigh fractionation of O & C isotopes with radiogenic isotope mixing studies helps to constrain decarbonation processes.

这一具体的研究应用集中在复杂的浸入交代反应系统，它间接地与从岩浆挥发分演化到伴生金属络合物的远端沉淀的光谱有关；这是我对夕卡岩系统研究的扩展，它产生了几个关键影响，最显著的是：1)在混合挥发接触交代系统中突出了一些重要的相关系，2)溶液-主岩反应过程中的渗透率演化结合物理化学反应的分析，以及3)一些衍生火成岩、它们的气体和喷发/角砾岩类型的激发性岩石成因解释具有广泛的意义。这些贡献都是相互关联的，因为复杂的反馈机制(即从脱碳前沿的二氧化碳反渗透)影响到流体-矿物-熔体相关系(即降低P(H2O))，从而影响气体形态、蒸汽饱和度和临界行为、金属分配，即Fe、Cu、Au、W、Mo等，直至实际的火山过程。这包括在不同压力下的差异脱气，这可能导致高盐度流体到盐或碳酸盐熔体(一些富铁盐到碳酸盐熔体)，这可能解释某些与夕卡岩有关的矿床系统的一些成因问题，即富磁铁矿的IOA和IOCG系统。最近对低T-高T超盐度体系中与SiO_2活度关系有关的流体反应方面的研究表明，SiO_2活度变化很大，影响矿化形成的钙硅酸盐的比例，这对解释许多这些有争议的体系至关重要。对各种浸润性夕卡岩的质量平衡分析补充了这项研究，尽管肯定具有挑战性；详细说明添加到交代系统中和(或)从交代系统中移除的物质的比例有助于限制与渗透反应交代系统相关的流体-岩石反应的程度，观察到的元素流动性(流体-岩石比)，以及这些内外接触反应区的机制。最具挑衅性的方面重新审视了硅酸盐岩浆相互作用过程中与高温岩浆夕卡岩作用有关的两个端元挥发熔融和石灰岩-岩浆反应。这些挥发熔剂向共熔过程的转变要求更好地理解复杂的高温夕卡岩形成过程，包括混合挥发浸渗性脱碳平衡和碳酸盐溶解度与碳酸盐熔融的关系、控制碳酸盐硅酸盐差动脱气的开放和封闭体系反应、碳酸盐不混溶及其侵位过程，包括爆炸性火山作用；脱气显著改变了这些体系的P？V爆炸性增强。O&C同位素的瑞利分馏和放射性同位素混合研究有助于限制脱碳过程。