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

大陆是复杂的构造集合体，已经演化了数亿年。在地球历史上，地球上的大陆曾多次合并和分散，形成了“超级大陆”。虽然大陆的运动在近代历史上是相当众所周知的，但关于它们在古代大陆中的位置和作用的知识在地质时代变得越来越零碎。这一提议涉及一个独特的太古代（超过25亿年）地壳块体，即雷克拉通，位于北美前寒武纪地盾的中心，被称为劳伦蒂亚。在劳伦西亚，雷克拉通被其他五个独特的太古代地块所包围，这些地块在大约20亿年前聚集在一起，形成了地球上第一个超大陆“努纳”。雷克拉通曾被认为与其最近的邻居赫恩克拉通相连，位于一个更古老的太古代陆块中，被称为“基诺兰”。然而，我们现在认识到，雷有特殊的特点，有别于赫恩，这表明它起源于一个独立的大陆，'努纳武特'。因此，雷伊似乎是一个古老大陆的一部分（25亿至23亿年的努纳武特），并在分裂后并入另一个（20亿至18亿年的努纳）。拟议的研究将调查Rae克拉通的构造历史，以更好地了解它从努纳武特的起源地到大约20亿年前的努纳的旅程。工作将集中在沿着阿萨巴斯卡地区的西西南Rae边缘，这是一个研究影响Rae的构造事件的极好实验室。一个主要的目的是描述与25亿至23亿年前的造山期（阿罗史密斯造山带）有关的构造活动，该造山带将雷伊与其他太古代地块区分开来。这种更好的理解将有助于验证和更好地建立雷伊从一个古老的大陆到另一个大陆的旅行步骤。在更广泛的范围内，这将有助于确定超大陆概念是否可以应用于前寒武纪，如果可以的话，如何应用。它还将揭示地球早期发展的一个重要时期，古元古代早期（25亿至20亿年前），当时地球系统发生了重大变化，如大陆的出现（高于海平面），大气的氧化，第一次重大的冰川作用，以及地壳结构和构造风格的根本变化，包括现代板块构造的可能开始。

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.