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

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）提供独特的数据和理解。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，必须考虑每个英国GDF场地的侵蚀影响，深度达1000 m。岩石表面侵蚀（即剥蚀）涉及到所有的地质过程，这些地质过程在海拔和地形方面都会减少地球表面。英国是构造稳定的（即非造山环境），化学风化和随后的侵蚀占岩石侵蚀的很大一部分;因此，本研究将侧重于量化侵蚀率作为剥蚀的指标。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;（3）创建未来100万年特定地点岩石类型和气候条件侵蚀潜力的“查找表”。该项目将使用一种新的、最先进的发光侵蚀仪（Smedley等人，2021年），以前所未有的长度和时间尺度得出岩石表面侵蚀率。该技术的原理是，随着时间的推移，随着岩石表面深度的增加，发光信号在更长时间暴露于阳光下时会重置到更大的深度，这是可以测量的。侵蚀的作用是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品的地球化学和晶体学，并确定控制岩石对侵蚀反应的化学、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主办英国GDF的地点收集（例如，坎布里亚郡，林肯郡），并将评估其不同的背景：主机基岩（目标1），寒冷的气候条件（目标2）。目标1：宿主岩石环境可以控制岩石表面的侵蚀速率（例如，Hall等人，2012年）。然而，这种控制的重要性往往被掩盖，因为数据是从各种各样的气候带汇编的，即，环境变量掩盖了岩石类型的任何影响（例如，Shaw等人，2012）。岩石类型将对英国未来100万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为GDF确定的场地）具有高度可变的当地岩石类型，强度从低到高，量化英国GDF场地所在地质的潜在侵蚀率至关重要。该项目将使用新的发光侵蚀仪，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。目标二：在过去100万年的冰川-间冰期循环中，英国目前没有岩石侵蚀率的记录;因此，不可能知道未来100万年预计会有多少侵蚀。一项针对不同气候变量（但不包括英国）的岩石露头侵蚀速率的全球研究记录了140 m/Ma的最大侵蚀速率（Portenga和Bierman，2011年），其中气候参数可以解释部分变异性。虽然英国可能是一个非造山环境，被认为具有低侵蚀率，但环境变量（特别是寒冷的温度和高降水量）和寄主岩石性质的综合影响

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