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。尽管各大洲的相对较新的运动是相当众所周知的，但对它们在古代陆地中的位置和角色的了解变得越来越零散地回溯到地质时代。该提议涉及一个独特的大古老（超过25亿年）的地壳块，雷·克拉顿（Rae Craton）位于北美前寒武纪盾牌中，被称为劳伦蒂亚（Laurentia）。在劳伦蒂亚（Laurentia）内，雷·克拉顿（Rae Craton）周围被其他五个独特的大帝块包围，这些块被组装了约20亿（GA），形成了地球上第一个超大陆的努纳（Nuna）。雷·克拉顿（Rae Craton）曾经被认为与其最近的邻居霍恩·克拉顿（Hearne Craton）相连，该地名是肯诺兰（Kenorland）。但是，RAE现在被认为具有特殊特征，将其与Hearne区分开来，并表明它可能起源于独立的大陆，约2.6至2.3 Ga Nunavutia。 Rae的边缘在萨斯喀彻温省 - 阿尔伯塔省 - 南北的西北部西北部的阿萨巴斯卡地区充分暴露了，那里的nunavutia构造构造融合的前寒武纪记录被标记分手的特征重叠，然后是分散块的重新组装，以〜2.0-1.8 ga nuna。我们建议研究该地区，因为它代表了研究RAE地质历史的出色实验室。在此过程中，我们旨在表征2.5至2.3 GA Arrowsmith Mountain-Building情节的驱动力，该插曲与Rae截然不同，并更好地确定该利润如何向年轻人（1.99-1.93 GA）Taltson Mountain-Build-Build-Build-Build-Building情节。这种提高的理解将既可以验证并更好地在Rae的旅行中建立步骤，从而从一个古老的陆地（Nunavutia）到另一个（Nuna）。它还将阐明地球早期开发中的一个重要时期，即早期的古四元（2.5至20亿年前），当时地球系统中发生了重大变化，例如大陆的出现（高于海平面），大气的氧化以及甲壳层建筑和构造风格的基本变化，包括现代型平板图案的可能性。