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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716679
• 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、分散和聚集是全球地球动力学的一个基本特征，既是长期全球周期的示踪物，也是核、幔和地壳长期演化的可能驱动力。最近十亿年的地球演化已经见证了一系列的超级大陆，从Rodinia到Gondwana和Pangea到欧亚大陆，涉及到板块的相对运动，通过不断演变的板块边界进行调解。全球古地理学的演变为理解地球的基本长期变化提供了重要的背景，包括过去的古气候极端（如全球冰川），海水地球化学和新元古代古生代的生命多样化。在此期间，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，以及地球发电机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，这需要原始的古地磁数据。古地磁学是确定大陆和板块过去运动的一种重要的定量地球物理工具。古地磁学与地质年代学相结合，非常适合于推断古板块和大陆之间的方向和时间关系，作为古代板块及其运动的代表。我提出的古地磁和构造研究计划调查的古大陆劳伦提斯（北美+格陵兰岛和北方爱尔兰，苏格兰）与西冈瓦纳和冈瓦纳相关的古陆的相互作用，从新元古代后期的Rodinia通过中古生代组装的泛古陆解体。通过在劳伦提斯和华南地区的新工作，将建立早古生代标志性事件（如奥陶纪生物多样性大事件（GOBE）和古气候变化）的古地理。实地工作预计将在加拿大大西洋/安大略、摩洛哥的反阿特拉斯和中国南方逐个项目进行。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，沿着相关的地质年代学和其他支持性研究，将作为几个学生论文的一个组成部分，并通过合作完成。这项研究计划的总体目标是解决有关板块构造关系的关键问题，孤立的古大陆，古陆和冈瓦纳元素之间的关系，从埃迪卡拉纪到志留纪的全球古地理学还知之甚少，为生物圈和古气候中的重大事件提供一个至关重要的背景。拟议的研究计划将把我的学生和他们的工作在当前的辩论的核心，这些重大事件和过程，彻底改变了地球在从新元古代世界Rodinia的过渡到晚古生代世界的盘古大陆。