Tectonic evolution of orogenic infrastructure, plateau development and collapse

造山基础设施的构造演化、高原发育与崩塌

• 批准号: RGPIN-2014-03808
• 负责人: Gibson, Daniel
• 金额: $ 2.7万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=708256
• 关键词: Tectonic; evolution; orogenic; infrastructure; plateau

The collision of continents, microcontinents, and island arcs at subduction zones where tectonic plates converge is a fundamental mountain building process referred to as collisional orogenesis. Throughout Earth's history, these collision zones give rise to expansive mountain belts that influence long-term global climate patterns, and have sutured crustal fragments together to create stable cratons and past supercontinents. Although a fundamental process in shaping Earth's crustal architecture, our understanding of these complex and dynamic systems is far from complete. The Canadian Cordillera provides excellent opportunity to study processes at all crustal levels within a large collisional orogen. The overarching theme of my research program is concerned with the processes that led to the development of the entire Cordilleran orogenic system. In turn, this provides critical insight into the fundamental processes that are common to all large orogenic systems, and allow for a more accurate comparison of the Cordillera with other similarly large collisional orogens, such as the Himalaya and Grenville. My current research emphasis is on the tectono-metamorphic infrastructure of the Canadian Cordillera, focusing on deformational and metamorphic processes that were active in the deepest levels of the orogen. My research has demonstrated that the metamorphic infrastructure records a protracted history of Mesozoic metamorphism, anatectic melting and ductile flow. I propose to test hypotheses that stem from these contributions. Hypothesis 1:) The metamorphic infrastructure of the southern Canadian Cordillera evolved beneath a northeastward propagating plateau since Middle Jurassic to Paleogene time. By mid-Cretaceous time the hypothesized plateau may have been greater than 500 km across and 5 km above sea level, slightly bigger than the Altiplano plateau in the South American Andes. This has important implication both for modeling the tectonic evolution of the Canadian Cordillera and for paleoclimate modeling of Cretaceous North America assuming a plateau of Altiplano proportions would have affected the weather patterns moving across the North American continent in a similar fashion to that crossing the Altiplano today. In the mid- to lower crustal levels beneath the plateau, deformation was likely accommodated by penetrative ductile flow, not by stacking of discrete thrust sheets. The style of flow evolved from a broad, distributed detachment zone, to incipient channel flow and gravitational spreading brought on by widespread anatectic melting during the peak and waning stages of orogenesis. Hypothesis 2:) Previous research suggests the tectonic development and history of terrane accretion in the northern Canadian Cordillera is out of sync with the south. However, results from my research program lead me to suggest there is a Mesozoic synchroneity between their respective metamorphic infrastructures. Additionally, the Mesozoic infrastructure in Yukon may have been a source of hydrothermal fluids that led to orogenic gold development within the Klondike-White Gold districts. Complementary HQP-led studies will be undertaken using state-of-the-art structural, petrological and thermochronometric analyses within the metamorphic infrastructure both across, and along strike, of the Cordilleran orogen. The data generated will be used to test the existence of the plateau, constrain its height, width, duration and exhumation, and to test if its development was synchronous with the metamorphic infrastructure in the northern Cordillera. These results will also be used to constrain parameters for modeling that will attempt to simulate the development of the Cordilleran infrastructure, the plateau and the style of ductile flow beneath it.

俯冲带构造板汇聚的俯冲带的大陆，微型内部和岛弧的碰撞是一种基本的山区建筑过程，称为碰撞造山学。在整个地球的历史中，这些碰撞带产生了宽阔的山带，影响了长期的全球气候模式，并将地壳碎片缝合在一起，以创造稳定的克拉通和过去的超强。尽管塑造地球地壳结构的基本过程，但我们对这些复杂和动态系统的理解远非完整。 加拿大Cordillera为在大型碰撞造山机中的所有地壳水平研究过程提供了绝佳的机会。我的研究计划的总体主题涉及导致整个Cordilleran造山系统发展的过程。反过来，这提供了对所有大型造口系统共有的基本过程的重要洞察力，并可以更准确地比较山脉与其他类似的大型碰撞orogens，例如喜马拉雅山和格伦维尔。 我目前的研究重点是加拿大山脉的构造构造基础构造基础设施，重点是变形和变质过程，这些过程活跃于最深层的造成造成水平。我的研究表明，变质基础设施记录了中生代变质，解剖融化和延性流的持久史。我建议检验源于这些贡献的假设。 假设1 :)加拿大南部山脉的变质基础设施从中部侏罗纪至古近期时代以来向东北传播高原的发展。到白垩纪中期，假设的高原可能已经超过500公里，海拔500公里，比南美安第斯山脉的Altiplano高原略大。这对于建模加拿大Cordillera的构造演变以及白垩纪北美的古气候建模具有重要意义，假设高原比例的高原将影响与当今Altiplano相似的北美大陆的天气模式。 在高原下方的地下层中的中层层中，穿透性延性流动可能会适应变形，而不是通过堆叠离散推力板的堆叠。流动的风格从宽阔的分布式脱离区演变为在造山机发生的峰值和衰减阶段，引起的频道流量和引力扩散。 假设2 :)以前的研究表明，加拿大北部山脉的构造发展和地形增生历史与南方不同步。但是，我的研究计划的结果使我表明它们各自的变质基础设施之间具有中生代的同步性。此外，育空地区的中生代基础设施可能是水热液的来源，导致了克朗代克白金区域内的造型金发育。 互补的HQP领导的研究将使用最先进的结构，岩石学和热化学分析，内部的变质基础设施内的跨山脉造山机的变质基础设施进行了研究。生成的数据将用于测试高原的存在，限制其高度，宽度，持续时间和挖掘，并测试其发育是否与北部Cordillera的变质基础设施同步。这些结果还将用于约束建模参数，以模拟山脉基础设施，高原和延性流动的风格的开发。