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.

大陆是经过数亿年演化的复杂构造聚合体。在地球历史上，地球的大陆曾多次合并和分散，形成超大陆。尽管各大洲相对较新的运动已广为人知，但追溯到地质时代，对它们在古代陆地中的位置和作用的了解却变得越来越零散。该提案涉及一个独特的太古代（超过 25 亿年）地壳块，Rae 克拉通，位于北美前寒武纪地盾（称为劳伦西亚）的中心。在劳伦大陆内，雷伊克拉通周围环绕着另外五个独特的太古宙地块，这些地块在约 20 亿 (Ga) 年前聚集在一起，形成了地球上的第一个超级大陆努纳 (Nuna)。雷伊克拉通曾经被认为与其最近的邻居赫恩克拉通相连，赫恩克拉通位于一块被称为肯诺兰的陆地上。然而，现在人们认识到雷伊河具有特殊特征，将其与赫恩河区别开来，并表明它可能起源于一块独立的陆地，约 2.6 至 2.3 Ga 努纳武蒂亚。 Rae边缘在萨斯喀彻温省-阿尔伯塔省-西北地区南部的阿萨巴斯卡西部地区充分暴露，努纳武特地区构造合并的前寒武纪记录与标志着分裂的特征重叠，随后分散的块体重新组装形成~2.0-1.8嘎努纳。我们提议调查该地区，因为它是监测雷伊地质历史的绝佳研究实验室。在此过程中，我们的目标是描述 Rae 特有的 2.5 至 2.3 Ga 阿罗史密斯造山事件的驱动力，并更好地确定这一边缘如何向年轻的 (1.99-1.93 Ga) 塔尔森过渡造山情节。这种加深的理解将有助于验证和更好地确定雷伊从一个古老大陆（努纳武蒂亚）到另一个古老大陆（努纳）的旅行步骤。它还将揭示地球早期发展的一个重要时期，即古元古代早期（2.5至20亿年前），当时地球系统发生了重大变化，例如大陆的出现（海平面以上）、地球的氧化作用等。大气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。