The tertiary magmatic sweep, Nevada, and early proterozoic tholeiitic/alkaline/peralkaline plutonism, Northwest Territories

内华达州第三纪岩浆扫掠区和西北地区早元古代拉斑岩/碱性/过碱性深成岩作用

• 批准号: 194153-2009
• 负责人: Cousens, Brian
• 金额: $ 1.6万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=496895
• 关键词: tertiary; magmatic; sweep; Nevada; early

The goals of this project are to a) better understand the sources of igneous rocks emplaced during the last 40 million years in the western United States, and b) investigate igneous activity associated with breakup of an old supercontinent in the southern Northwest Territories of Canada. The past 40 million years has been a time of intense volcanic activity in the southwestern United States, particularly Nevada, accompanied by stretching and faulting of the crust. Volcanism swept methodically from northeast to southwest across Nevada, presumably a result of the subduction of the Farallon Plate beneath North America. We understand very little of how volcanism was linked to the subducting plate or crustal stretching, what the sources for the volcanic rocks were, and to what degree this igneous activity was responsible for contemporaneous gold mineralization in Nevada. We seek to identify the sources of magmas, either in the mantle or in the crust (or both), and better describe the timing of the sweep of volcanism across northern and western Nevada. In the Northwest Territories, an igneous intrusive complex was emplaced along the East Arm of Great Slave Lake around 2 billion years ago, carrying with it rocks rich in Nb, Ta, and rare earth elements, all important to industry. The intrusions mark a new period in the history of the region, where, after a long period of geological quiescence, an old continental landmass was split into fragments that allowed these intrusions to rise to the surface. Understanding the geochemistry and origin of the intrusions and the relationships between them will improve models for the origin of the economically important rare earth minerals and add to the exploration effort for more mineralization in the area.

该项目的目标是a）更好地了解过去4000万年来在美国西部汇集的火成岩的来源，b）调查与加拿大西北部南部地区一座古老超大陆的破裂有关的火成点。 在过去的4000万年中，在美国西南部，特别是内华达州进行了激烈的火山活动时期，伴随着地壳的伸展和断层。 火山主义从东北到西南部的内华达州有条不紊地扫过，这可能是北美下方的法拉隆板块的俯冲结果。 我们对火山主义如何与俯冲板或地壳伸展的联系很少了解，火山岩的来源是什么，以及这种火成岩活动在多大程度上导致了内华达州同时的金矿化。 我们试图在地幔或外壳（或两者兼皮）中确定岩浆的来源，并更好地描述整个内华达州北部和西部火山主义的时机。 在西北地区，大约20亿年前大约20亿湖的东臂沿着大奴隶湖的东臂扩散了一个火成岩的侵入性综合体，并带有富含NB，TA和稀土元素的岩石，这对工业很重要。 入侵标志着该地区历史上的一个新时期，经过长时间的地质静止，旧的大陆陆地被分为碎片，使这些侵入升至表面。 了解入侵的地球化学和起源及其之间的关系将改善经济上重要的稀土矿物质的起源，并增加该地区更多矿化的探索工作。