Comparative orogenesis of accretionary orogens

增生造山带的比较造山作用

• 批准号: RGPIN-2018-03967
• 负责人: vanStaal, Cees
• 金额: $ 4.37万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750864
• 关键词: Comparative; orogenesis; accretionary; orogens

Accumulated field evidence suggest that there was a secular change in tectonic style from the Archean to present. Some of the answers how and why orogenesis seems to have changed in style over time may come from insight into why tectonic processes, such as arc-arc and/or arc-continent collisions change in nature along and across strike in some mountain belts. Accretionary orogens provide the best opportunity to research this topic, because accretions of arcs and other tectonic elements are commonly short-lived and associated deformation is typically localized. My ongoing tectonic research in the Appalachian-Caledonide mountain belt and the North- and South American Cordillera has documented that the arc-continent collisions that form part of these accretionary orogens, locally changed from hard (penetrative shortening and metamorphism of upper plate extends beyond the arc-trench gap) and hot to soft (upper plate shortening localised in arc-trench gap, but not beyond) and cold along and/or across strike (e.g Taconic, Famatina and Klondike orogenies), whereas others show little or no variation and remained soft and cold (e.g. Penobscot, Salinic, Antler and Pampean orogenies). The controlling tectonic parameters and processes responsible for these variations in tectonic style are poorly known. Comparative research based on multidisciplinary studies of important aspects of these orogens showing major variations in tectonic style in critical areas with relatively good exposure and geochronological constraints, are geared to identify the characteristic structures and/or other tectonic elements shared by such mountain belts. The results will stimulate developing hypotheses capable of explaining the differences in tectonic style, which will be further tested by research in other mountain belts showing large variations in tectonic style along and/or across strike, such as the Beishan orogen of the Central Asian Orogenic Belt (CAOB) and comparisons with existing numerical modelling results and 3-D laboratory-based experiments.Student research proposed herein focusses on investigating the ridge-subduction model for forming the Liuyuan ophiolite complex in the Beishan orogen and its potential impact on the observed variations in tectonic style (hard vs soft) in this mountain belt (PhD1) and the syn-collision exhumation of eclogites in the Baie Verte area of the Newfoundland Appalachians (PhD2), a process extremely rare or absent elsewhere in the Northern Appalachians. The eclogites occur in a segment of the Laurentian margin that was hyperextended prior to subduction, whereas the adjacent upper plate forearc basin and accretionary prism are largely absent, probably due to tectonic removal by forearc underthrusting. These and/or other factors may have had a bearing on the along strike variations in tectonic style of the Taconic orogeny.

积累的现场证据表明，从太古宙至今，构造风格发生了长期变化。随着时间的推移，造山运动的风格如何以及为何发生变化，一些答案可能来自于对为什么构造过程（例如弧-弧和/或弧-大陆碰撞）在一些山带中沿着和跨越走向发生性质变化的深入了解。增生造山带为研究这一主题提供了最佳机会，因为弧和其他构造元素的增生通常是短暂的，并且相关的变形通常是局部的。我正在进行的阿巴拉契亚-喀里多尼德山脉以及北美和南美科迪勒拉的构造研究记录了形成这些增生造山带一部分的弧大陆碰撞，局部从硬（上板块的穿透缩短和变质作用延伸到弧沟间隙之外）和热到软（上板块缩短集中在弧沟间隙内，但不超出）以及沿和/或跨走向的冷 （例如塔科尼克（Taconic）、法马蒂纳（Famatina）和克朗代克（Klondike）造山带），而其他造山带则几乎没有变化，并且保持柔软和寒冷（例如佩诺布斯科特（Penobscot），萨利尼克（Salinic），安特勒（Antler）和潘皮安（Pampean）造山带）。造成这些构造样式变化的控制构造参数和过程知之甚少。基于对这些造山带重要方面的多学科研究的比较研究显示，在具有相对良好的暴露和地质年代学限制的关键区域中，构造样式存在重大变化，旨在确定这些造山带共有的特征结构和/或其他构造要素。这些结果将激发能够解释构造样式差异的假说，这些假说将通过对沿和/或跨走向构造样式变化较大的其他山带（例如中亚造山带（CAOB）的北山造山带）的研究以及与现有数值模拟结果和基于3D实验室的实验的比较来进一步检验。本文提出的学生研究重点是研究山脊俯冲模型 北山造山带柳园蛇绿岩杂岩的形成及其对该山带构造样式（硬与软）变化的潜在影响（PhD1）以及纽芬兰阿巴拉契亚拜伊韦尔特地区榴辉岩的同碰撞折返（PhD2），这一过程在北阿巴拉契亚其他地区极为罕见或不存在。榴辉岩出现在劳伦斯边缘的一段区域，该区域在俯冲之前过度伸展，而邻近的上板块弧前盆地和增生棱柱基本上不存在，可能是由于弧前逆冲的构造去除作用。这些和/或其他因素可能对塔科造山带构造风格的沿走向变化产生影响。