Global paleogeography and geodynamics of the Proterozoic to Paleozoic transition

全球古地理和元古代到古生代过渡的地球动力学

• 批准号: RGPIN-2019-07249
• 负责人: McCausland, Philip
• 金额: $ 1.82万
• 依托单位: University of Western Ontario
• 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=751159
• 关键词: Global; paleogeography; geodynamics; Proterozoic; Paleozoic

Supercontinent breakup, dispersal and assembly is a fundamental feature of global geodynamics, both as a tracer of long-term global cycles and as a possible driver of core, mantle and crustal secular evolution. The most recent billion years of Earth evolution has seen a succession of supercontinents, from Rodinia to Gondwana and Pangea to Eurasia, involving the relative motions of plates, mediated via evolving plate boundaries. The evolution of global paleogeography provides an important context for understanding fundamental secular changes in the Earth, including past paleoclimate extremes (such as global glaciation), seawater geochemistry and the Neoproterozoic - Paleozoic diversification of life. During this time the Earth appears to have also undergone large geodynamic changes including possible major true polar wander events, reorganization of global mantle convection, and changes in the geometry and strength of the geodynamo. These questions are all best addressed within a global plate tectonic framework which requires primary paleomagnetic-based data. Paleomagnetism is a key quantitative geophysical tool for defining the past motions of continents and terranes. Paleomagnetism, in conjunction with geochronology, is ideally suited to deduce the orientation and timing relationships between terranes and continents, as representatives of the ancient plates and their motions. My proposed paleomagnetic and tectonic research program investigates the interaction of the paleocontinent Laurentia (North America + Greenland and Northern Ireland, Scotland) with West Gondwana and Gondwana-related terranes from the Late Neoproterozoic breakup of Rodinia through the mid Paleozoic assembly of Pangea. Early Paleozoic paleogeography of signature events such as the Great Ordovician Biodiversification Event (GOBE) and changes in paleoclimate will be developed via new work in Laurentia and South China. Fieldwork is anticipated to take place on a project-by-project basis in Atlantic Canada/Ontario, Anti-Atlas of Morocco and South China. Paleomagnetic laboratory work will be done at the Western Paleomagnetic and Petrophysical Laboratory (WPPL) to obtain primary results. This paleomagnetic research, along with associated geochronology and other supporting research, will be done as an integral part of several student theses and via collaborations. The overall goal of this proposed research program is to solve key questions concerning plate tectonic relations between isolated paleocontinents, terranes and elements of Gondwana in the as-yet poorly understood global paleogeography from Ediacaran though Silurian time, to provide a crucial context for major events in the biosphere and paleoclimate. The proposed research program will place my students and their work at the heart of current debates about the significant events and processes which drastically changed Earth during the transition from the Neoproterozoic world of Rodinia to the Late Paleozoic world of Pangea.

超大陆的分裂、分散和组合是全球地球动力学的一个基本特征，既是全球长期循环的示踪剂，也是核、地幔和地壳长期演化的可能驱动力。最近10亿年的地球演化见证了一系列的超级大陆，从罗迪尼亚到冈瓦纳，从盘古大陆到欧亚大陆，涉及到板块的相对运动，通过不断进化的板块边界来调解。全球古地理的演化为理解地球的基本长期变化提供了一个重要的背景，包括过去的古气候极端事件（如全球冰川作用）、海水地球化学和新元古代-古生代的生命多样化。在这段时间里，地球似乎也经历了巨大的地球动力学变化，包括可能的重大真极漂移事件、全球地幔对流的重组以及地球动力的几何形状和强度的变化。这些问题最好在全球板块构造框架内解决，这需要基于原始古地磁的数据。古地磁是确定大陆和地体过去运动的关键定量地球物理工具。古地磁学与地质年代学相结合，作为古代板块及其运动的代表，非常适合推断大地和大陆之间的方位和时间关系。我提出的古地磁和构造研究计划研究了从罗迪尼亚晚新元古代分裂到中古生代盘古大陆组合的古大陆Laurentia（北美+格陵兰岛和北爱尔兰，苏格兰）与西冈瓦纳和冈瓦纳相关的地体的相互作用。在Laurentia和华南地区的新工作将进一步发展早古生代古地理特征，如大奥陶纪生物多样化事件（Great Ordovician biodiversity Event， GOBE）和古气候变化。实地考察预计将在加拿大大西洋/安大略、摩洛哥Anti-Atlas和华南地区逐个项目进行。古地磁实验室工作将在西部古地磁和岩石物理实验室（WPPL）进行，以获得初步结果。这项古地磁研究，以及相关的地质年代学和其他支持研究，将作为几个学生论文的一个组成部分，并通过合作进行。本研究计划的总体目标是解决从埃迪卡拉纪到志留纪全球古地理中孤立古大陆、地体和冈瓦纳大陆元素之间的板块构造关系的关键问题，为生物圈和古气候的重大事件提供关键背景。拟议的研究项目将把我的学生和他们的工作置于当前争论的核心，即在从罗迪尼亚新元古代世界到盘古大陆晚古生代世界的过渡期间，地球发生了重大变化的事件和过程。