Combining paleofluid chemistry and rock characterization to constrain genetic processes in tungsten deposits.

结合古流体化学和岩石表征来限制钨矿床的成因过程。

• 批准号: RGPIN-2018-05744
• 负责人: LecumberriSanchez, Pilar
• 金额: $ 2.19万
• 依托单位: University of Alberta
• 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=683390
• 关键词: Combining; paleofluid; chemistry; rock; characterization

Ore deposits are major geochemical anomalies. Precipitation of metal-bearing phases can be spatially and temporally localized. However, the geochemical processes that lead to metal precipitation can leave signatures over ranges of several kilometers and over thousands to millions of years. The systematic spatial and temporal variability in these systems provides indication of which are the main geochemical processes at work and what are potential good indicators of mineralization and vectors toward fluid and heat sources. The main objective of this research program is to combine the chemistry of ore fluids with the chemical and mineralogical composition of host rocks to constrain some of the major controls in ore deposit formation. ***In the next five years I will focus on studying tungsten deposits. Tungsten is a critical metal, with Canada being one of the five major producers worldwide and NWT being a major exporter historically. The conditions under which tungsten occur geologically are fairly common (thick metasedimentary packages with associated reduced magmatism). However tungsten deposits are highly localized. In particular the Tungsten belt in the border between NWT and YK constitutes the only major tungsten-producing province in western North America. Therefore this program will focus on (1) determining whether tungsten fertility is controlled at the hydrothermal stage or at an earlier stage (at fluid-melt partitioning or melt source) and the implications for global distribution, (2) determining the hydrology of hydrothermal systems formed at deep conditions using tungsten deposits as an example and (3) define which elements characterize tungsten mineralizing fluids and at which scale they are likely to cause anomalies.***The approaches used in this project towards chemical characterization of fluids will include petrography, fluid inclusion thermometry and laser ablation inductively coupled plasma mass spectrometry. These techniques will provide information on how the PT conditions of entrapment, volatile and cation content of the fluid vary in tungsten-rich vs tungsten-poor systems and how they change with time and space. Combination with secondary electron microscopy and ion microprobe will provide paired information on how changes in the source of fluids may influence the evolution of paragenesis and fluid chemistry over time. Further characterization of fluid-rock interaction in the host rocks will be achieved through portable techniques (X-ray fluorescence), whole rock analyses through conventional XRF and digestion methods, XRD and SEM. Combination of fluid chemistry with hand sample and ore scale mineralogy and chemistry will provide information on which elements are likely to be buffered locally and which ones are likely to cause distal anomalies associated with these deposit types.

矿床是地球化学的主要异常。含金属相的沉淀可以在空间和时间上局部化。然而，导致金属沉淀的地球化学过程可以在数千年到数百万年的范围内留下签名。这些系统的系统性空间和时间变化提供了指示，哪些是主要的地球化学过程在工作中，什么是潜在的良好的矿化和载体的流体和热源的指标。本研究计划的主要目标是将成矿流体的化学性质与寄主岩石的化学和矿物学组成联合收割机结合起来，以限制成矿存款形成中的一些主要控制因素。*** 在未来的五年里，我将专注于研究钨矿床。钨是一种重要的金属，加拿大是全球五大生产国之一，而NWT历来是主要出口国。钨在地质上出现的条件相当普遍（厚的变质沉积岩包与相关的还原岩浆作用）。然而，钨矿床高度局部化。特别是西北地区和YK之间边界的钨带构成了北美西部唯一的主要产钨省。因此，本项目的重点是（1）确定钨的肥力是在热液阶段还是在早期阶段受到控制（在流体-熔体分配或熔体源）和对全球分布的影响，（2）以钨矿床为例，确定了深部热液系统的水文特征;确定哪些元素是钨矿化流体的特征，以及它们在多大程度上可能导致异常。本项目中使用的流体化学表征方法包括岩相学、流体包裹体测温法和激光烧蚀电感耦合等离子体质谱法。这些技术将提供有关富钨与贫钨系统中流体的截留、挥发物和阳离子含量的PT条件如何变化以及它们如何随时间和空间变化的信息。结合二次电子显微镜和离子微探针将提供配对的信息如何在流体的来源的变化可能会影响共生和流体化学随时间的演变。将通过便携式技术（X射线荧光）、通过传统的X射线荧光和消化方法进行的全岩分析、XRD和SEM，进一步确定主岩中流体-岩石相互作用的特征。将流体化学与手工取样和矿石鳞片矿物学和化学相结合，将提供关于哪些元素可能局部缓冲以及哪些元素可能导致与这些存款类型相关的远端异常的信息。