Global paleogeography and geodynamics of the Proterozoic to Paleozoic transition

超大陆的分裂、扩散和组装是全球地球动力学的一个基本特征，既是长期全球循环的踪迹，也是核、地幔和地壳长期演化的可能驱动因素。在地球最近10亿年的演化中，经历了一系列的超大陆，从罗迪尼亚到冈瓦那，从盘古到欧亚大陆，涉及到板块的相对运动，通过不断演变的板块边界来调节。全球古地理的演变为了解地球上的根本长期变化，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-古生代生物多样性提供了重要的背景。在此期间，地球似乎也经历了巨大的地球动力学变化，包括可能的重大真正极地漂移事件，全球地幔对流的重组，以及地球发电机的几何和强度的变化。所有这些问题都在全球板块构造框架内得到了最好的解决，这需要原始的古地磁数据。古地磁是确定大陆和地体过去运动的一个关键的定量地球物理工具。古地磁学与地质年代学相结合，非常适合于推断地体与大陆之间的方位和时间关系，作为古代板块及其运动的代表。我建议的古地磁和构造研究计划调查古陆劳伦蒂亚(北美+格陵兰岛和北爱尔兰，苏格兰)与新元古代晚期罗迪尼亚裂解到中古生代泛古生代组合的西冈瓦那和与冈瓦纳有关的地体的相互作用。早古生代标志性事件的古地理，如大奥陶纪生物多样化事件(GOBE)和古气候变化，将通过劳伦西亚和南中国的新工作来发展。预计将在大西洋加拿大/安大略省、摩洛哥反地图集和南中国逐个项目地开展实地工作。将在西部古地磁和岩石物理实验室(WPPL)开展古地磁实验室工作，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辅助研究，将作为几篇学生论文的组成部分并通过合作完成。这项拟议的研究计划的总体目标是解决埃迪卡拉纪至志留纪全球古地理中孤立的古大陆、地体和冈瓦那元素之间的板块构造关系的关键问题，为生物圈和古气候中的重大事件提供关键的背景。拟议的研究计划将把我的学生和他们的工作置于当前辩论的核心，这些重大事件和过程在从新元古代的罗迪尼亚世界过渡到晚古生代的盘古世界期间极大地改变了地球。

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.