Mafic Layered Intrusions Through Time

随着时间的推移，镁铁质层状侵入

• 批准号: 249474-2013
• 负责人: Scoates, James
• 金额: $ 2.91万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=524667
• 关键词: Mafic; Layered; Intrusions; Through; Time

Mafic layered intrusions crystallize from basaltic magma to form large bodies of igneous rocks that exhibit prominent layering, preserving stunning rock records of the processes by which magma evolves within the Earth's crust. These intrusions contain world-class deposits of chromium (Cr), platinum group elements (PGE), and vanadium (V), metals that are vital to industry and society in general. Despite their scientific and practical importance, precise age constraints are lacking and many aspects of their origin and formation are still poorly known. The proposed research aims to fill these critical knowledge gaps and will take advantage of recent analytical developments and state-of-the-art instrumentation to constrain the age, duration, and cooling of mafic layered intrusions. This will be achieved by detailed fieldwork and geochemical analysis of rocks and minerals from some of the world's largest and most influential layered intrusions that collectively represent a significant span of Earth history (over 2.5 billion years): (1) the Stillwater Complex, the exposed fragment of a large layered intrusion in the Beartooth Range of the Wyoming Archean Province, including the PGE-rich J-M Reef, (2) the Bushveld Complex, the world's largest layered intrusion, located in the northern Kaapvaal craton of South Africa, and host to some of the richest Cr-PGE-V ore deposits on Earth, (3) the Great Dyke, a 550 km-long layered intrusion in the Zimbabwe craton of southern Africa, containing the world's second largest reserve of PGE, (4) the Kiglapait Intrusion, a bowl-shaped intrusion exposed in the Nain Plutonic Suite of coastal Labrador, and (5) the Skaergaard Intrusion of eastern Greenland, one of the most remarkable layered igneous bodies on Earth that is related to thick sequences of continental flood basalts and opening of the North Atlantic Ocean. The proposed research will yield new scientific insights on timescales of magmatic processes and cooling for these striking rocks, challenging presently known basic concepts of magma crystallization and evolution. The results of this work will have direct implications for the origin of magmatic ore deposits and can be applied to the investigation of less well-studied intrusions in Canada and worldwide.

镁铁质层状侵入岩由玄武岩岩浆结晶而成，形成大量火成岩，表现出突出的分层，保存了地壳内岩浆演化过程的令人惊叹的岩石记录。这些侵入岩含有世界级的铬(Cr)、铂族元素(PGE)和钒(V)矿床，这些金属对工业和社会总体来说都是至关重要的。尽管它们在科学上和实践上都很重要，但缺乏精确的年龄限制，它们的起源和形成的许多方面仍然鲜为人知。拟议的研究旨在填补这些关键的知识空白，并将利用最近的分析发展和最先进的仪器来限制镁铁质层状侵入体的年龄、持续时间和冷却。这将通过对一些世界上最大和最有影响力的层状侵入体的岩石和矿物进行详细的野外调查和地球化学分析来实现，这些侵入体共同代表了地球历史(超过25亿年)的一个重要跨度：(1)静水杂岩，怀俄明州太古代熊牙山脉大型层状侵入体的暴露碎片，包括富含PGE的J-M礁；(2)布什维尔德杂岩，位于南非卡瓦瓦克拉通北部，是世界上最大的层状侵入体，拥有地球上一些最丰富的铬-铅-钒矿床，(3)大堤，位于南部非洲津巴布韦克拉通的550公里长的层状侵入体，其中包含世界第二大PGE储量：(4)基拉帕特侵入体，这是暴露在拉布拉多沿海的奈恩深成岩套中的一个碗形侵入体；(5)格陵兰东部的斯卡尔加德侵入体，这是地球上最引人注目的层状火成岩之一，与大陆洪水玄武岩的厚层序列和北大西洋的开放有关。这项拟议的研究将对这些引人注目的岩石的岩浆作用和冷却的时间尺度产生新的科学见解，挑战目前已知的岩浆结晶和演化的基本概念。这项工作的结果将对岩浆矿床的成因产生直接的影响，并可用于加拿大和世界范围内研究较少的侵入岩的调查。