Tectonic evolution of the WSW Rae craton, Athabasca region, Canada: Laboratory for study of Precambrian crustal processes

加拿大阿萨巴斯卡地区 WSW Rae 克拉通的构造演化：前寒武纪地壳过程研究实验室

• 批准号: RGPIN-2016-05320
• 负责人: Bethune, Kathryn
• 金额: $ 1.75万
• 依托单位: University of Regina
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615624
• 关键词: Tectonic; evolution; WSW; Rae; craton

Continents are complex tectonic aggregations that have evolved over hundreds of millions of years. The continents of the earth have coalesced and dispersed several times in earth's history forming ‘supercontinental’ landmasses. Whereas the movements of the continents are fairly well known in recent history, knowledge of their positions and roles in ancient landmasses becomes increasingly fragmentary going back in geological time. This proposal deals with a distinctive Archean (greater than 2.5 billion year) crustal block, the Rae craton, located centrally in the Precambrian shield of North America, known as Laurentia. Within Laurentia, the Rae craton is surrounded by five other distinctive Archean blocks that were assembled ~2 billion years ago to form Earth’s first supercontinent, ‘Nuna’. Rae craton was once thought to be connected to its nearest neighbour, the Hearne craton, in an even older Archean landmass known as ‘Kenorland’. However, we now recognize that the Rae has special characteristics, distinctive from the Hearne, suggesting that it originated from an independent landmass, ‘Nunavutia’. The Rae therefore appears to have been part of one ancient landmass (2.5 to 2.3 billion year 'Nunavutia') and, following break-up, became incorporated in another (2.0 to 1.8 billion year old 'Nuna'). The proposed research will investigate the tectonic history of Rae craton to better understand its journey from its place of origin within Nunavutia to its later involvement in Nuna about 2 billion years ago. Work will focus along the west-southwest Rae margin in the Athabasca region, an excellent laboratory for study of tectonic events that affected the Rae through time. A major aim is to characterize tectonic activity associated with a 2.5 to 2.3 billion-year-old mountain-building episode, the Arrowsmith orogeny, which sets Rae apart from other Archean blocks. This improved understanding will serve both to verify and better establish steps in Rae’s travels from one ancient landmass to the other. On a broader scale, this will help determine whether, and if so how, the supercontinental concept can be applied to the Precambrian. It will also shed light on an important period in early earth development, the early Paleoproterozoic (2.5 to 2.0 billion years ago), when significant changes occurred in the earth system such as the emergence of the continents (above sea level), oxygenation of the atmosphere, the first significant glaciations, as well as fundamental changes in crustal architecture and tectonic style, including the probable onset of modern-style plate tectonics.

大洲是复杂的构造聚集，已经发展了数亿年。地球大陆在地球历史上融合并分散了多次，形成了“超大陆”陆地。尽管延续的运动在最近的历史上是广为人知的，但在地质时期，人们对它们在古代地块中的地位和角色的了解变得越来越零散。该提案涉及一个独特的大古老（超过25亿年）的地壳块，Rae Crateon位于中央位于北美前寒武纪（称为Laurentia）。在劳伦蒂亚（Laurentia）内，雷·克拉特（Rae Crateon）周围被其他五个独特的大国块包围，这些街区大约是20亿年前，形成了地球上第一个超大陆的“努纳”（Nuna）。雷·克拉特（Rae Crateon）曾经被认为与其最近的邻居赫恩·克拉特（Hearne Crateon）相连，该邻居在一个年龄较大的大老人大麻中被称为“ kenorland”。但是，我们现在认识到，RAE具有与Hearne不同的特殊特征，这表明它起源于独立的大陆“ Nunavatia”。因此，RAE似乎是一个古老的陆地（2.5至23亿年的“ Nunavatia”）的一部分，并且在分手后，已纳入另一个（2.0至18亿年的“ Nuna”）。拟议的研究将调查Rae Crateon的构造历史，以更好地了解其从Nunavatia在Nunavatia起源的旅程到大约20亿年前在Nuna的后期参与。工作将集中在阿萨巴斯卡地区的西南偏远地区，这是一项研究构造事件的绝佳实验室，这些实验室影响了随着时间的推移影响Rae。一个主要目的是表征与2.5至23亿年历史的山区建设情节有关的构造活动，即Arrowsmith造型，这使Rae与其他Archean块区分开来。这种改善的理解将既可以验证和更好地在Rae的旅行中，从一个古老的地质到另一个。在更广泛的规模上，这将有助于确定是否以及如何将超大概念应用于前寒武纪。它还将阐明地球早期发展的重要时期。古元古代（2.5至20亿年前），当时地球系统发生了重大变化，例如延续的出现（海平面上方），大气的氧合，第一次重要的冰川造成的氧合，以及地壳结构和构造风格的根本变化，包括现代板岩板板探测的问题发作。