Understanding the processes that affect isotopic ages to resolve both time and rates of geologic processes

板块构造理论为理解在地球系统中循环物质的地质过程提供了一个框架，并解释了为什么地震沿着板块边界定位。然而，它并没有充分解释大陆内部的构造过程。 现代大地测量数据显示，大陆内部正在积极变形，表明构造活动并不局限于活动的板块边界。岩石圈强度的变化是控制大陆内部变形局部化的重要因素，并提出了一个关键问题：岩石圈的力学性质在构造活动和时间上是如何变化的？ 要提取关于地质系统的这种时间和热信息，需要了解决定岩石圈热结构的物理过程的相互作用。使用温度敏感的辐射测量方法对岩石的热历史进行定量研究称为热年代学，包括测定矿物通过特定闭合温度的时间。了解同位素对温度和变形的反应将为岩石圈的热机械状态提供新的见解。 在这个赠款周期中，我将研究影响岩石中同位素流动性的物理化学因素，以解决下地壳变形过程中破裂和流动之间的相互作用。由于压力、温度和流体活动的增加，这一地壳区域的岩石力学性质发生了戏剧性的变化。 我假设，同位素在地质系统中的扩散重新分布可以在干燥、静态的条件下发生，这对扩散速率和确定热事件的持续时间都有影响。有了这些数据，将通过在时间和空间上考虑脆性和韧性模型之间的相互作用来评估岩石圈的整体强度和动力学。这些潜在的相互作用将通过几个项目来探索，这些项目涉及与高素质人员(HQP)的实地和实验室调查。 马斯格雷夫山脉(澳大利亚)和卑尔根弧(挪威)中的超裸露岩石被选为天然实验室，提供了对下地壳剪切带发展的独特见解，并使下地壳变形模型能够得到严格的评估。尽管这两个地区的寄主麻粒岩(干岩)相似，但它们的不同之处在于，剪切带在马斯格雷夫山脉是干燥的，在卑尔根弧是潮湿的。 这一计划的结果预计将为我国带来地区性和广泛性的好处，例如通过改善对石雕等传统商品的获取，发展努纳武特的经济独立性，并确保加拿大的矿产勘探和开采能力能够在竞争激烈的全球市场中脱颖而出。

Plate tectonic theory provides a framework for understanding geologic processes that cycle material through Earth systems, and explains why earthquakes are localized along plate boundaries. It does not however, adequately explain tectonic processes in the interior of continents. Modern geodetic data show continental interiors are actively deforming, indicating tectonic activity is not limited to active plate boundaries. Variation of lithospheric strength is an important factor controlling the localization of deformation in continental interiors, and raises the key question: how do the mechanical properties of the lithosphere change during tectonic activity and time? Extraction of this temporal and thermal information on geologic systems requires understanding the interplay of physical processes determining the thermal structure of the lithosphere. The quantitative study of the thermal history of rocks using temperature-sensitive radiometric methods is called thermochronology, and involves dating the time at which a mineral passes through a specific closure temperature. Understanding how isotopes respond to temperature and deformation will provide new insights into the thermomechanical state of the lithosphere. In this grant cycle, I will study physicochemical factors affecting the mobility of isotopes in rocks to address the interplay between fracture and flow during deformation in the lower crust. Dramatic changes in mechanical rock property take place in this crustal region by increased pressure, temperature, and fluid activity. I hypothesize the diffusional redistribution of isotopes in a geologic system can take place under dry, static conditions, which has implications for diffusion rates and for determining the duration of thermal events. With these data, the bulk strength and dynamics of the lithosphere will be assessed by considering, in time and space, the interplay between brittle and ductile models. These potential interactions will be explored through several projects involving field and laboratory investigation with highly qualified personnel (HQP). The superbly exposed rocks in the Musgrave Ranges (Australia) and Bergen Arcs (Norway) are chosen as natural laboratories providing a unique insight into the development of lower crustal shear zones and allow models for lower crustal deformation to be evaluated critically. Although the host granulite (dry rock) of these two areas are similar, they differ in that the shear zones are dry in the Musgrave Ranges and wet in the Bergen Arcs. Results of this program are anticipated to yield both regional and widespread benefits for our country, such as developing the economic independence of Nunavut through improved access to traditional commodities like carving stone, and ensuring Canada's mineral exploration and extraction capabilities are able to excel in a competitive global marketplace.