Where does helium come from (to eventually form strategic resources)?

氦是一种稀有气体，在自然界中也很罕见，在地球大气中的平均浓度为5.24 ppm。氦有两种同位素，原始来源的3 He和岩石中铀和钍衰变产生的4 He。放射性4 He是一种战略资源，具有众多的工业和医疗应用，但目前，人类正面临着全球范围内的氦短缺。原因是需求增加和供应减少的结合，后者是由天然气田中高品位氦储量稀少造成的。这些矿床的成因，其中一些自世纪初就已为人所知，但仍知之甚少，并在调查中。该发现研究计划将重点研究控制沉积盆地中氦积累的过程和机制以及可开采储量如何形成。氦的形成、积累和保存需要特定的地质条件。据推测，富铀的基底岩石和/或源岩是主要来源。由于氦的稀有性，人们相信氦是在甲烷或氮气等载气中迁移到被低渗透盐岩覆盖的地质圈闭中的。所有这些条件当然是必要的，但还不足以解释世界上发现的少数高品位氦储量。事实上，仍然有许多机制和过程需要深入研究，例如氦从岩石释放到沉积流体中的过程。我的研究小组新发现的铀同位素比值234 U/238 U和4 He/3 He比值之间的关系表明，幕式岩石破裂可以释放大量的氦到周围环境中，解释了地下水中存在大量放射性氦。可能的是，幕式岩石破裂也可以发挥作用，在控制高品位氦储量的氦积累。通过多方面的方法，包括案例研究，实验室实验和建模，我的研究计划将测试地壳流体中氦的释放和积累的构造控制假设。短期目标旨在回答以下问题：是什么过程控制着地壳流体中氦的释放和积累？以什么速度？地质构造在某种程度上控制了高品位氦资源的形成吗？长期目标是建立高品位He成因的可靠模型，并为其勘探提供可靠的地球化学工具。对于加拿大和整个北美来说，这是一个及时而紧迫的问题，因为加拿大正在耗尽其储备，并失去其在该行业的战略地位。从事该主题的HQP将获得跨越许多不同学科和技术的科学知识和技能，这对学术界或天然气/石油行业的未来职业生涯将是宝贵的。

Helium is a noble gas which is also rare in nature, with an average concentration in the Earth's atmosphere of 5.24 ppm. Helium has two isotopes, 3He of primordial origin, and 4He, produced by decay of Uranium and Thorium in rocks. Radiogenic 4He is a strategic resource for its numerous industrial and medical applications, but presently, humanity is facing a worldwide shortage of helium. The reason is the combined increasing demand and decreasing supply, the latter caused by the rarity of high-grade helium reserves in natural gas fields. The genesis of these deposits, some of them known since the early 20e century, are still poorly understood and under investigated. This discovery research program will focus on studying the processes and mechanisms that control helium accumulation in sedimentary basins and how exploitable reserves are formed. Helium requires specific geological conditions to be formed, accumulated and preserved. It is assumed that uranium-rich basement rocks and/or source rocks are the main source. Because of its rarity, it is believed that helium migrates in a carrier gas, such as methane or nitrogen, into geological traps capped by low-permeability salt rocks. All of these conditions are certainly necessary, but not sufficient, to explain the few high-grade helium reserves found worldwide. Indeed, there are still numerous mechanisms and processes which require intense investigation, such as the processes of helium release from rocks into sedimentary fluids. Newly discovered relationships between uranium isotope ratios 234U/238U and 4He/3He ratios by my research group suggests that episodic rock fracturing can release large amounts of helium into the surrounding environment, explaining the presence of large amounts of radiogenic helium in groundwater. It is likely that episodic rock fracturing could also play a role in controlling helium accumulation in high-grade He reserves. Through a multifaceted approach including case studies, laboratory experiments, and modelling, my research program will test the hypothesis of a tectonic control in the release and accumulation of helium in crustal fluids. Short-term objectives are aimed to answer the following questions: What process controls helium release and accumulation in crustal fluids? At what rates? Does tectonics somehow control the formation of high-grade helium resources? The long-term goal is to elaborate robust models of high-grade He genesis and offer reliable geochemical tools for their exploration. This is a timely and urgent problem for Canada and for North America in general, which is exhausting its reserves and loosing its strategic place in this industry. HQP working on the subject will gain scientific knowledge and skills spanning many different disciplines and techniques, which will be precious for future careers in academia or gas/oil industry.