Supercontinent formation processes recorded in the Appalachian-Caledonide Orogen

在地球历史上，超级大陆已经存在过几次；最著名的是盘古大陆，从大约3.5亿年到大约2亿年前，它包含了地球的大部分大陆地壳。盘古大陆是由几个独立的大陆建造的，它们本身就是由较早的超大陆解体而来的。拟议的研究计划将调查这些大陆的汇聚和融合，这些大陆在一系列碰撞中汇聚在一起，形成了北美的阿巴拉契亚山脉和欧洲西北部的喀里多尼德山脉。*导致盘古大陆形成的最早事件是古生代伊阿普图斯和瑞克大洋俯冲引发的板块会聚。俯冲开始是海洋演化“威尔逊循环”中最鲜为人知的部分。与加拿大和英国的合作者一起，我们提出了一个新的俯冲启动模式，该模式涉及寒武纪进入伊阿普图斯/瑞克大洋的“加勒比海”板块边界。这一模型有助于解释伊阿普图斯大陆两个边缘的明显同时变形，并表明这些边缘的构造作用类似于加勒比海的现代边缘。*为了验证这些预测，我们将测定砂岩中的锆石颗粒的年龄，以寻找主要大陆沉积物在较小地体(如阿瓦洛尼亚和甘德里亚)中的第一批到达。我们将使用我们的碎屑锆石数据库来测试和开发客观的统计指标，以便在不同人群之间进行比较。我们将对岩石结构进行野外测绘和实验室调查，并分析古地磁信息，以确定盘古大陆组装时阿巴拉契亚山脉碰撞的性质，无论是倾斜的还是垂直的。*在这次合并的最新阶段，加拿大大西洋开发的马里泰斯沉积盆地允许沉积12公里的石炭纪地层，包括自然资源：煤、石油、天然气、石膏、盐和钾盐。容纳这一沉积堆积的地壳减薄和下沉可能是斜向断层运动的结果。然而，我们最近的结果表明，沉积物堆内的盐流强烈地修改了沉降史。因此，马里泰斯盆地为研究走滑和斜滑环境中盐的行为提供了一个天然的实验室。我们将确定沿解剖盆地的主要断层的作用和运动量，并确定它们如何影响盐的行为和沉积物的沉积。*这项研究将有助于更好地理解：俯冲启动过程；走滑和斜向运动在超大陆形成中的作用；走滑断层运动和盐运动的相互作用；以及加拿大东部古生代岩石中自然资源的分布。**

Supercontinents have existed at several times in Earth history; the best known is Pangea, which contained most of the Earth's continental crust from about 350 to about 200 million years ago. Pangea was built from several separate continents, themselves derived from earlier supercontinent breakup. The proposed program of research will investigate the convergence and amalgamation of these continents, which came together in a series of collisions, building the Appalachian mountain range of North America and the Caledonides of NW Europe. ***The earliest events leading to the formation of Pangea were the initiation of plate convergence by subduction in the Paleozoic Iapetus and Rheic oceans. Subduction initiation is the most poorly understood part of the "Wilson Cycle" of ocean evolution. With collaborators in Canada and Britain, we have proposed a new model for subduction initiation involving a "Caribbean style" plate boundary that entered the Iapetus/Rheic oceans in the Cambrian Period. This model helps to explain apparently simultaneous deformation on both margins of the Iapetus, and suggests that tectonism on those margins was analogous to the modern margins of the Caribbean. ***To test these predictions we will date zircon grains in sandstones to seek the first arrivals, in smaller terranes (e.g. Avalonia and Ganderia), of sediment from major continents. We will use our detrital zircon database to test and develop objective statistical measures for comparisons between populations. We will carry out field mapping and laboratory investigations of rock structures, and analyze paleomagnetic information, to determine the nature of collisions in the Appalachians, whether oblique or orthogonal, as Pangea was assembled.***During the latest stages of this amalgamation, the Maritimes Sedimentary Basin developed in Atlantic Canada, allowing deposition of >12 km of Carboniferous strata including natural resources: coal, oil, natural gas, gypsum, salt and potash. The crustal thinning and subsidence that accommodated this sediment pile probably resulted from oblique fault movements. However, our recent results have shown that the flow of salt within the sediment pile strongly modified the subsidence history. The Maritimes Basin thus provides a natural laboratory for investigating the poorly understood behaviour of salt in strike-slip and oblique-slip settings. We will determine the role and amount of movement along the major faults that dissect the basin, and determine how they influenced the behaviour of salt and the deposition of sediments.***This research will lead to improved understanding of: the process of subduction initiation; the role of strike-slip and oblique movements in supercontinent formation; the interaction between strike-slip faulting and salt movement; and the distribution of natural resources in Paleozoic rocks of eastern Canada.**