Tectonic evolution of the WSW Rae craton of Laurentia: Laboratory for study of Precambrian crustal processes

劳伦西亚 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-2022-03429
• 负责人: Bethune, Kathryn
• 金额: $ 3.13万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=755031
• 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 relatively recent movements of the continents are well fairly known, 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 within 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 (Ga) years ago to form Earth's first supercontinent, Nuna. The Rae craton was once thought to be connected to its nearest neighbour, the Hearne craton, in a landmass known as Kenorland. However, the Rae is now recognized to have special characteristics, setting it apart from the Hearne, and indicating that it likely originated from an independent landmass, ~2.6 to 2.3 Ga Nunavutia. The Rae margin is well exposed in the western Athabasca region of Saskatchewan-Alberta-southern NWT where the Precambrian record of tectonic amalgamation of Nunavutia are overlapped by features marking break-up, followed by re-assembly of dispersed blocks to form ~2.0-1.8 Ga Nuna. We propose to investigate this region because it represents an excellent laboratory for study to monitor the Rae's geologic history. In doing so, we aim to characterize the driving forces of the 2.5 to 2.3 Ga Arrowsmith mountain-building episode, which is distinctive to the Rae, as well as to better establish how this margin transitioned toward the younger (1.99-1.93 Ga) Taltson mountain-building episode. This improved understanding will serve both to verify and better establish steps in Rae's travels from one ancient landmass (Nunavutia) to another (Nuna). 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 and fundamental changes in crustal architecture and tectonic style, including the probable onset of modern-style plate tectonics.

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，形成超级大陆。虽然大陆相对较近的运动是众所周知的，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。在劳伦大陆内，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20亿年前组装在一起，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，位于一个被称为凯诺兰的陆块中。然而，雷现在被认为具有特殊的特征，将其与赫恩分开，并表明它可能起源于一个独立的陆块，约2.6至2.3 Ga努纳武特。Rae边缘在萨斯喀彻温省-艾伯塔省-西北地区南部的阿萨巴斯卡西部地区出露良好，在那里，Nunavutia构造合并的前寒武纪记录被标志着断裂的特征所重叠，随后分散的块体重新组装形成~2.0-1.8 Ga Nuna。我们建议调查这一地区，因为它代表了一个很好的实验室，研究监测雷的地质历史。在这样做的过程中，我们的目标是表征的驱动力的2.5至2.3 Ga阿罗史密斯造山事件，这是独特的雷，以及更好地建立这种利润率如何过渡到年轻（1.99-1.93 Ga）塔尔森造山事件。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（努纳武特）到另一个（努纳）的旅行步骤。它还将揭示早期地球发展的一个重要时期，即古元古代早期（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），大气的氧化以及地壳结构和构造样式的根本变化，包括现代风格的板块构造的可能开始。