Lithium Isotope Distribution in Hydrothermal Alteration from the Cochenour Extension of the Red Lake Gold Mine, Ontario

安大略省红湖金矿 Cochenour 延伸区热液蚀变中的锂同位素分布

• 批准号: 535883-2018
• 负责人: Nadeau, Olivier
• 金额: $ 1.82万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Engage Grants Program
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=660566
• 关键词: Lithium; Isotope; Distribution; Hydrothermal; Alteration

Goldcorp is one of the largest gold producers in the world and is actually developing its Cochenour mine, located on the old Cochenour-Willans mine site within the Red Lake district, Ontario, and connected to the Red Lake mine through an underground 5 km haulage drift. At Cochenour, two different types of mineralizations are identified: (1) replacement-style mineralization with/without arsenopyrite; and (2) quartz-actinolite vein-style mineralization with visible gold. The company-specific problem is that although the concentration of arsenic can act as a proxy for gold when arsenopyrite is present, no geochemical proxy has yet been identified for replacement-style mineralization without arsenopyrite or for vein-style mineralization. The objective of this research is to verify if the lithium isotope ratio (d7Li) of hydrothermally-altered rock surrounding the gold mineralization could act as a proxy for both styles of mineralization. It was previously demonstrated that the d7Li of hydrothermally altered rocks could correlate with gold at Kirkland Lake Gold Inc.'s Macassa Gold Mine (Nadeau, 2017) and it is likely that this correlation may also be present at the Cochenour deposit. The rationale behind the use of Li isotopes is that like Na and K, Li is a mobile alkaline element and is thus involved in hydrothermal alterations. However, because Li is present in rocks/fluids in trace concentrations, it follows a non-ideal Henrian behaviour and is thus controlled by partitioning between minerals and fluids. Furthermore, Li has 2 stable isotopes which fractionate readily via water-rock interactions so the Li concentration and the 7Li/6Li ratio of hydrothermally altered rocks should allow tracing the sources and pathways of hydrothermal fluids within hydrothermally-altered environments. The reason why partial correlation of d7Li and Au was identified at Kirkland Lake Gold Inc.'s Macassa mine has remained unclear and the present research aims to study a simpler system in a single type of lithology in order to shed light on the relations that exist between gold mineralization and lithium isotopic ratios.

Goldcorp是世界上最大的黄金生产商之一，实际上正在开发其Cochenour矿山，该矿山位于安大略省红湖地区的老Cochenour-Willans矿山，并通过地下5公里的运输平巷与红湖矿山相连。在Cochenour，确定了两种不同类型的矿化：（1）含/不含毒砂的交代式矿化;（2）含可见金的石英-阳起石脉式矿化。该公司特有的问题是，虽然砷的浓度可以作为一个代理金时，毒砂存在，没有地球化学代理尚未确定的交代式矿化没有毒砂或脉式矿化。本研究的目的是验证是否锂同位素比值（d 7 Li）的热液蚀变岩周围的金矿化可以作为一个代理的两种类型的矿化。先前在柯克兰湖黄金公司证明，热液蚀变岩石的d 7 Li可以与黄金相关。的Macassa金矿（Nadeau，2017），这种相关性很可能也存在于Cochenour存款中。使用锂同位素的基本原理是，像钠和钾一样，锂是一种移动的碱性元素，因此与热液蚀变有关。然而，由于Li以痕量浓度存在于岩石/流体中，因此它遵循非理想的Henrian行为，因此受矿物和流体之间的分配控制。此外，锂有2个稳定的同位素，容易通过水-岩石相互作用破裂，因此热液蚀变岩石的锂浓度和7 Li/6Li比率应允许追踪热液流体在热液蚀变环境中的来源和路径。在柯克兰湖黄金公司确定了d 7 Li和Au的部分相关性的原因。的Macassa矿仍然不清楚，目前的研究旨在研究单一类型岩性中的一个更简单的系统，以阐明金矿化与锂同位素比值之间存在的关系。