Dynamics and tectono-metamorphic framework of ultra-high temperature orogenic systems

超高温造山系统的动力学和构造变质格架

• 批准号: RGPIN-2022-04812
• 负责人: Thiessen, Eric
• 金额: $ 1.89万
• 依托单位: Memorial University of Newfoundland
• 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=751188
• 关键词: Dynamics; tectono; metamorphic; framework; ultra

Ultrahigh-temperature (UHT) crustal metamorphism on the regional-scale (>50,000 km2) occurs when the decay of radiogenic isotopes produces crustal heat to temperatures >900 °C in long-lived (40-100 million-year), thickened mountain belts (orogens) such as beneath modern-day Tibetan Plateau. However, mantle heat transfer into the crust, through magmatic underplating, intrusion, or delamination processes, may be common, significant, and underappreciated in regional UHT terranes worldwide. Resolving the relative contributions of mantle and crustal heat sources in continental crust will impact our understanding of middle- to lower-crust evolution and their thermal, physical and chemical changes in orogenic systems. The Taltson Orogen, Northwest Territories, Canada, is a regional-scale UHT orogen that reached UHT and subsequently cooled in <30 million-years, requiring a significant component of mantle heat transfer in addition to crustal-derived radiogenic heat production. My research program aims to evaluate and quantify the amount of mantle-derived heat input into the Taltson Orogen crust, by using a structural, metamorphic, geochronological numerical and petrologic approach. This research will target the Taltson Orogen guided by three objectives: 1) determine the largest possible contribution of mantle-derived heat sources, 2) establish a modern structural and tectono-metamorphic framework, and 3) evaluate evidence for mantle-derived heat input. Studies will involve field observations and targeted sampling followed by collection of micro-analytical chemical, isotopic, age and structural data. Methods will include whole rock geochemistry, petrologic modelling and detailed pressure-temperature-time-deformation path construction, in situ age (U-Pb zircon, monazite, titanite, rutile; Lu-Hf garnet; Ar-Ar & Rb-Sr mica) and trace-element analyses, and kinematic and rheologic analyses of shear zones. Quantifying mantle-derived versus crustal-derived heat sources will facilitate testing the hypothesis that mantle heat contributions play an important role in regional-scale UHT terranes. In turn, this research stands to significantly improve our understanding of the evolution of the thermal, structural, and rheologic dynamics of UHT orogenic systems. This work will also help resolve a long standing controversy on whether the Taltson Orogen formed by thickening of a continental back-arc or by thickening in a Tibetan plateau like setting. Furthermore, this work will allow us to examine the Taltson Orogen's currently debated role in the amalgamation of the supercontinent Nuna and evaluate its far-field tectonic effects, including its control on the distribution of mineral deposits, throughout the Canadian Shield.

超高温（UHT）地壳变质作用在区域尺度（> 50，000平方公里）上发生，当放射性同位素的衰变产生的地壳热量超过900 °C时，在长寿命（4000 - 1亿年），加厚的山脉带（造山带），如现代青藏高原。然而，地幔热传递到地壳中，通过岩浆底侵，侵入，或拆沉过程，可能是常见的，重要的，和低估的区域超高温地幔。解决地幔和地壳热源在大陆地壳中的相对贡献，将影响我们对造山系统中中下地壳演化及其热、物理和化学变化的理解。加拿大西北地区的Taltson造山带是一个区域规模的超高温造山带，在3000万年内达到超高温并随后冷却，除了地壳衍生的放射性生热外，还需要地幔热传递的重要组成部分。我的研究计划的目的是评估和量化的地幔热量输入到塔尔森造山带地壳，通过使用结构，变质，地质年代学数值和岩石学的方法。这项研究将以Taltson造山带为目标，有三个目标：1）确定幔源热源的最大可能贡献，2）建立现代结构和构造变质框架，3）评估幔源热输入的证据。研究将包括实地观察和有针对性的取样，然后收集微观分析化学、同位素、年龄和结构数据。方法将包括全岩地球化学、岩石学建模和详细的压力-温度-时间-变形路径构建、原位年龄（U-Pb锆石、独居石、钛铁矿、金红石; Lu-Hf石榴石; Ar-Ar和Rb-Sr云母）和微量元素分析，以及剪切带的运动学和流变学分析。 定量地幔来源与地壳来源的热源将有助于检验地幔热贡献在区域尺度UHT热事件中起重要作用的假设。反过来，这项研究的立场，显着提高我们的理解的演化的热，结构和流变动力学的超高温造山系统。这项工作也将有助于解决一个长期存在的争议，即塔尔森造山带是由大陆弧后增厚形成的，还是在西藏高原样环境中增厚形成的。此外，这项工作将使我们能够研究Taltson造山带目前有争议的作用，在合并的超大陆努纳和评估其远场构造的影响，包括其控制的矿床的分布，整个加拿大地盾。