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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633770
• 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.

大陆、微大陆和岛弧在构造板块汇聚的俯冲带的碰撞是一个基本的造山过程，被称为碰撞造山作用。在整个地球历史中，这些碰撞带产生了影响长期全球气候模式的广阔山带。 ，并将地壳碎片缝合在一起，形成稳定的克拉通和过去的超级大陆，尽管这是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还远未完成。加拿大科迪勒拉山脉为研究大型碰撞造山带内所有地壳层面的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科迪勒拉造山系统发展的过程，这提供了重要的见解。深入研究所有大型造山带系统共有的基本过程，并能够更准确地比较科迪勒拉山与其他类似的大型碰撞造山带，例如喜马拉雅山和格伦维尔山。我目前的研究重点是加拿大科迪勒拉山脉的构造变质基础设施，重点关注活跃在造山带最深处的变形和变质过程。我的研究表明，变质基础设施记录了中生代变质作用、深熔熔融和韧性流的漫长历史。检验源自这些贡献的假设。假设 1:) 加拿大南部科迪勒拉山脉的变质基础设施在向东北传播的作用下演化而来到白垩纪中期，已勘探的高原可能直径超过 500 公里，海拔超过 5 公里，略大于南美安第斯山脉的高原高原。加拿大科迪勒拉山脉的构造演化以及北美白垩纪的古气候模型假设高原比例的高原会影响整个地区的天气模式北美大陆的变形方式与今天跨越高原的方式类似，在高原下方的中下地壳层，变形可能是通过穿透性延性流来调节的，而不是通过离散的逆冲片的堆积来调节的。假设 2：）先前的研究表明，造山作用的高峰和衰退阶段，广泛的深熔熔融所带来的早期河道流动和重力扩散。加拿大北部科迪勒拉山脉的构造发展和地体增生历史与南部不同步。然而，我的研究项目的结果使我认为它们各自的变质基础设施之间存在中生代同步性。此外，育空地区的中生代基础设施可能存在同步性。一直是导致克朗代克-白金地区造山金矿开发的热液来源。HQP 主导的补充研究将利用对科迪勒拉造山带沿线的变质基础设施进行最先进的结构、岩石学和热测时分析，生成的数据将用于测试高原的存在，限制其高度、宽度和持续时间。和折返，并测试其发展是否与北部科迪勒拉山脉的变质基础设施同步。这些结果还将用于限制建模参数，以尝试模拟科迪勒拉高原基础设施的发展。以及它下面的延性流的类型。