Supercontinent formation processes recorded in the Appalachian-Caledonide Orogen

超级大陆在地球历史上存在过好几次；最著名的是盘古大陆，它包含了大约3.5亿到2亿年前地球大陆地壳的大部分。盘古大陆是由几个独立的大陆组成的，而这些大陆本身是由早期的超大陆分裂而来的。拟议的研究计划将调查这些大陆的融合和融合，这些大陆在一系列碰撞中走到一起，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Iapetus和Rheic海洋的俯冲引起板块收敛。在海洋演化的“威尔逊旋回”中，俯冲起始是人们了解得最少的部分。与加拿大和英国的合作者一起，我们提出了一个新的俯冲起始模型，涉及寒武纪时期进入Iapetus/Rheic海洋的“加勒比风格”板块边界。这个模型有助于解释土卫八两侧同时发生的变形，并表明这些边缘的构造活动类似于现代加勒比海的边缘。***为了验证这些预测，我们将确定砂岩中的锆石颗粒的年代，以寻找来自主要大陆的沉积物在较小的地体（如阿瓦洛尼亚和甘德拉尼亚）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措施，以进行种群之间的比较。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，以确定在盘古大陆形成时，阿巴拉契亚山脉的碰撞性质，无论是斜碰撞还是正交碰撞。***在这次合并的最后阶段，加拿大大西洋沿岸的海利斯沉积盆地发展起来，石炭纪地层沉积了120公里，包括煤、石油、天然气、石膏、盐和钾肥等自然资源。容纳这一沉积物堆的地壳变薄和下沉可能是斜断层运动的结果。然而，我们最近的研究结果表明，盐在沉积物桩内的流动强烈地改变了沉降历史。因此，马里倍斯盆地为研究走滑和斜滑环境中鲜为人知的盐的行为提供了一个天然实验室。我们将确定沿解剖盆地的主要断层运动的作用和数量，并确定它们如何影响盐的行为和沉积物的沉积。***本研究将有助于加深对以下方面的认识：俯冲起始过程；走滑和斜向运动在超大陆形成中的作用；走滑断裂与盐运动的相互作用；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.**