Rock erosion during cold climates of the next 1 million years: risk assessment for siting a UK Geological Disposal Facility.

未来一百万年寒冷气候期间的岩石侵蚀：英国地质处置设施选址的风险评估。

• 批准号: 2889450
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2889450
• 关键词: Rock; erosion; during; cold; climates

This project will provide unique data and understanding for sites identified by community partners as a potential UK Geological Disposal Facility (GDF) for nuclear waste. A UK GDF will be located in bedrock at depths up to a 1000 m, but the access infrastructure that will be backfilled will extend to the surface; therefore, the impacts of erosion down to 1000 m depths must be considered for each UK GDF site. Rock surface erosion (i.e. denudation) relates to all of the geological processes that work to reduce the Earth's surface, both in terms of elevation and relief. The UK is tectonically stable (i.e. non- orogenic environment) where chemical weathering and subsequent erosion accounts for much of the rock erosion; thus, this study will focus upon quantifying erosion rates as indicators of denudation. It will adopt the following objectives: (1) quantifying long-term erosion rates for targeted rock-types of potential UK GDFs; (2) resolving erosion rates for past cold climates of the UK; (3) creating a "look-up table" of erosion potential for site-specific rock-types and climate conditions over the next 1 million years. The project will use a new, state-of-the art luminescence erosion-meter (Smedley et al. 2021) to derive rock surface erosion rates on unprecedented length and time scales. The technique works on the principle that the luminescence signal with depth into a rock surface resets to greater depths during longer exposure to sunlight over time, which can be measured. Erosion works to reduce the depth of that signal resetting, bringing it closer to the rock surface with higher erosion. Thus, for rock surfaces of known-age (e.g., existing cosmogenic nuclide dating), we can derive time-averaged erosion rates. The project will also apply state-of-the-art quantitative electron microscopy to measure the geochemistry and crystallography of rock samples and determine the chemical, physical and mechanical properties that control the rock response to erosion, and complement luminescence data (e.g., Prior, Mariani et al., 2009, Mariani et al., 2006). Rock samples for testing and analyses will be collected from locations identified by community partners to potentially host the UK GDF (e.g., Cumbria, Lincolnshire), and will be assessed for their different contexts: host bedrock (Objective 1), cold climate conditions (Objective 2). Objective 1: The host rock environment can control the erosion rates of rock surfaces (e.g., Hall et al. 2012). However, the importance of this control is often hidden because data is compiled from a wide variety of climate zones, i.e., the environmental variables mask any impact of the rock-type (e.g., Shaw et al. 2012). Rock-type will have a significant impact upon rock surface erosion in the UK over the next 1 million years. Given that the UK (and the sites currently identified by community partners for a GDF) has highly variable local rock-types with lower to higher strengths, it is vital to quantify the potential erosion rates of the geology that hosts a UK GDF site. This project will use the new luminescence erosion-meter to quantify long-term erosion rates for a variety of lower and higher strength host rock environments targeted for any UK GDF, in combination with detailed geochemical and structural analyses. Objective 2: There is currently no record of rock erosion rates in the UK over the glacial- interglacial cycles of the last 1 million years; thus, it is impossible to know how much erosion can be expected over the next 1 million years. A global study of rock outcrop erosion rates from across different climate variables (but not the UK) recorded a maximum erosion rate of 140 m/Ma (Portenga and Bierman, 2011) where climate parameters could explain some of the variability. Although the UK may be a non-orogenic environment considered to have low erosion rates, the combined impact of environmental variables (especially cold temperatures and high precipitation) and host rock properties

该项目将为社区合作伙伴确定的潜在英国核废料地质处置设施（GDF）地点提供独特的数据和了解。英国 GDF 将位于深度达 1000 m 的基岩中，但回填的通道基础设施将延伸至地表；因此，每个英国 GDF 场地都必须考虑 1000 米深处侵蚀的影响。岩石表面侵蚀（即剥蚀）与所有导致地球表面减少的地质过程有关，包括海拔和地形。英国构造稳定（即非造山环境），其中化学风化和随后的侵蚀造成了大部分岩石侵蚀；因此，本研究将重点关注量化侵蚀率作为剥蚀指标。它将采用以下目标：（1）量化潜在英国 GDF 的目标岩石类型的长期侵蚀率； (2) 解决英国过去寒冷气候的侵蚀率问题； (3) 创建未来 100 万年针对特定地点岩石类型和气候条件的侵蚀潜力“查找表”。该项目将使用一种新型、最先进的发光侵蚀计（Smedley 等人，2021）来得出前所未有的长度和时间尺度的岩石表面侵蚀率。该技术的工作原理是，随着时间的推移，随着时间的推移，长时间暴露在阳光下，岩石表面深度的发光信号会重置到更大的深度，这是可以测量的。侵蚀可以减少信号重置的深度，使其更接近侵蚀程度更高的岩石表面。因此，对于已知年龄的岩石表面（例如现有的宇宙成因核素测年），我们可以得出时间平均侵蚀率。该项目还将应用最先进的定量电子显微镜来测量岩石样本的地球化学和晶体学，并确定控制岩石对侵蚀的反应的化学、物理和机械特性，并补充发光数据（例如，Prior，马里亚尼等人，2009 年；马里亚尼等人，2006 年）。用于测试和分析的岩石样本将从社区合作伙伴确定的可能容纳英国 GDF 的地点（例如坎布里亚郡、林肯郡）收集，并将对其不同的环境进行评估：宿主基岩（目标 1）、寒冷气候条件（目标2）。目标 1：主岩环境可以控制岩石表面的侵蚀速率（例如，Hall 等人，2012）。然而，这种控制的重要性往往被隐藏，因为数据是从各种气候带编制的，即环境变量掩盖了岩石类型的任何影响（例如，Shaw 等人，2012 年）。岩石类型将对英国未来一百万年的岩石表面侵蚀产生重大影响。鉴于英国（以及社区合作伙伴目前确定的 GDF 地点）当地岩石类型的强度从低到高变化很大，因此量化英国 GDF 地点所在地质的潜在侵蚀率至关重要。该项目将使用新型发光侵蚀仪，结合详细的地球化学和结构分析，量化针对任何英国 GDF 的各种较低和较高强度主岩环境的长期侵蚀率。目标 2：目前英国没有过去 100 万年冰期-间冰期循环中岩石侵蚀率的记录；因此，不可能知道未来一百万年预计会有多少侵蚀。一项针对不同气候变量（但不是英国）的岩石露头侵蚀率的全球研究记录了最大侵蚀率为 140 m/Ma（Portenga 和 Bierman，2011），其中气候参数可以解释一些变化。尽管英国可能属于非造山环境，被认为具有较低的侵蚀率，但环境变量（特别是寒冷的气温和高降水量）和主岩性质的综合影响