Supercontinent formation processes recorded in the Appalachian-Caledonide Orogen

阿巴拉契亚-喀里多尼亚造山带记录的超大陆形成过程

• 批准号: RGPIN-2015-04425
• 负责人: Waldron, John
• 金额: $ 1.6万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612962
• 关键词: Supercontinent; formation; processes; recorded; Appalachian

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.

超级大陆在地球历史上存在过几次;最著名的是盘古大陆，它包含了大约3.5亿至2亿年前地球的大部分大陆地壳。盘古大陆是由几个独立的大陆组成的，它们本身又来自于早期的超大陆分裂。拟议的研究计划将调查这些大陆的融合和合并，这些大陆在一系列碰撞中走到一起，建立了北美的阿巴拉契亚山脉和西北欧的加里东山脉。 最早导致泛大陆形成的事件是古生代的土卫八和里克洋俯冲导致的板块聚合。俯冲起始是海洋演化的“威尔逊循环”中最不为人所知的部分。与加拿大和英国的合作者，我们提出了一个新的模式，俯冲开始涉及“加勒比风格”的板块边界，进入Iapetus/Rheic海洋在寒武纪。这一模型有助于解释土卫八两个边缘明显同时发生的变形，并表明这些边缘的构造运动类似于加勒比海的现代边缘。 为了验证这些预测，我们将对砂岩中的锆石颗粒进行测年，以寻找来自主要大陆的沉积物的第一批到达者，例如阿瓦隆尼亚和甘德里亚。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，用于人口之间的比较。我们将对岩石结构进行实地测绘和实验室调查，并分析古地磁信息，以确定阿巴拉契亚山脉碰撞的性质，无论是倾斜的还是正交的，因为盘古大陆是组装的。 在这一合并的最后阶段，加拿大大西洋沿岸的海洋沉积盆地得到发展，允许沉积超过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。地壳减薄和沉降，容纳这一沉积物堆可能是由于斜断层运动。然而，我们最近的研究结果表明，盐在沉积物堆内的流动强烈地改变了沉降历史。因此，滨海盆地提供了一个天然的实验室，调查知之甚少的行为，盐在走滑和蠕动滑动设置。我们将确定的作用和运动量沿着主要断层解剖盆地，并确定他们如何影响盐的行为和沉积物的沉积。 这项研究将导致更好的理解：俯冲开始的过程;在超大陆形成的走滑和斜向运动的作用;走滑断层和盐运动之间的相互作用;和自然资源的分布在加拿大东部的古生代岩石。