Geochemistry and Geochronology of Scheelites as constraints on the formation of gold ore deposits at Timmins West mine, Ontario

对于位于安大略省蒂明斯的Lake Shore GoldCorporation （Tahoe Canada / Tahoe Resources Inc.的全资子公司）等矿业公司来说，新的金矿越来越难找到。金矿找矿的关键参数是了解它们与地质作用的关系，准确地了解矿床的年龄。金矿床的年龄测定具有挑战性，因为它们可能形成于宿主侵入体之后，含金流体的来源可能与侵入体本身、变质作用或地壳或地幔的较深部分有关。此外，用于长寿命放射性衰变系统的元素不能很好地分解成金。邻近的矿物并不总是可靠的，因为它们可能在不同的流体存在下结晶，或者是矿化本身之前的矿物。因此，在西蒂明斯矿（TWM），目前还没有建立金矿化的年表。只有矿脉寄主岩石的年龄是可用的（Barrie, 1990），并且可能比成矿作用早数千万年。在TWM，在白钨矿（CaWO4）和钛矿（CaTiSiO5）旁边的矿脉中发现了金。在2016年使用NSERC Connectgrant成功访问Lake Shore之后，当我们与公司讨论我们可以使用什么地球化学和地质年代学工具来分析白钨矿时，我们建议在这里限制金属的来源，与金脉形成相关的地质过程，并确定它们的辐射年龄。了解什么时候和多少次事件导致了金矿化，对于建立一个导致蒂明斯金矿沉积的地质过程的“足迹”至关重要。我们的结果将为lake Shore Gold公司未来的潜在勘探区域提供限制。

New gold ore deposits are increasingly hard to find for mining companies such as Lake Shore GoldCorporation (a wholly owned subsidiary of Tahoe Canada / Tahoe Resources Inc.) in Timmins, Ontario. Keyparameters in gold exploration are to understand their relationship to geological processes and obtain preciseknowledge of the deposits' ages. Gold deposits are challenging to age date because they may be formed laterthan the host intrusions and the origin of the auriferous fluids can be associated with the intrusion itself,metamorphism or from deeper parts of the crust or mantle. Moreover, elements used for long-lived radioactivedecay systems do not partition well into gold. Neighbouring minerals are not always reliable either as they mayhave crystallized in the presence of different fluids or are minerals pre-dating the mineralization itself. As aconsequence, at the West Timmins mine (TWM), there is currently no chronology established for goldmineralization. Only the age of the host rocks of the veins are available (Barrie, 1990) and may pre-datemineralization by tens of million years. Gold is found in veins next to minerals such as scheelite (CaWO4) andtitanite (CaTiSiO5) at TWM. Following a successful visit of Lake Shore in 2016 using a NSERC Connectgrant, when we discussed with the company what geochemical and geochronological tools we can use foranalyzing scheelite, we propose here to constrain the source of metals, geological processes associated with theformation of gold veins, and determine their radiometric ages. Knowing when and how many events wereresponsible for gold mineralization is critical to build a "footprint" of the geological processes responsible forgold deposition in Timmins. Our results will provide constraints on potentially areas of future exploration forLake Shore Gold Corporation.