Fluids in the continental crust: decrypting geological processes using noble gases

大陆地壳中的流体：利用稀有气体解密地质过程

• 批准号: RGPIN-2015-05378
• 负责人: Pinti, Daniele
• 金额: $ 1.6万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613514
• 关键词: Fluids; continental; crust; decrypting; geological

The research program will focus on the origin and evolution of fluids in the lithosphere and the critical role they play in the geodynamical evolution of the continental crust. It will address fundamental questions about i) the duration and length of cross-formational fluid flow and its role in the crustal degassing; ii) the existence of fossil water as geological archives of the continental crust evolution; iii) the genesis and evolution of crustal fluids of economic interest, particularly geothermal fluids and shale gas. To meet these objectives, a series of projects will be undertaken in sedimentary and hydrothermal environments - at different spatial and temporal scales. Some focus will be put on the processes responsible for vertical migration of gaseous species (methane, helium…) in aquifers, and the genesis of seepage on continents, with natural laboratory being the St. Lawrence Lowlands (QC). Studies will be aimed at quantifying methane fluxes and model the process of transport from Utica shale. These models will be translated to the Island of Anticosti where tight gas exploitation is sought. Another important aspect that will be explored is the occurrence of hundreds millions to billions years old fluids in deep mining environments and their role in mineralization along the Cadillac fault in Abitibi-Temiscamingue. Parallel to this NSERC research program, we are carrying out a detailed study of the evolution of hydrothermal fluids in the largest active geothermal systems of Mexico in order to assess their lifetime and power capacities. These hydrothermal environments are the modern analogue of the fossil epithermal ore deposits. The large chemical and isotopic database that will be acquired will be crucial to understand the relation between metals and fluid sources in these environments, a premise to future ore genesis models. The tremendous and unique expertise we are developing on geothermal systems will be also applied to the study of the geothermal capacity of some Canadian Provinces, in particular the genesis of the Banff’s geothermal area. The methodological approach to trace the origin and evolution of these “geofluids” is based on the isotopes of conservative elements, namely noble gases, for which I have a unique expertise in Canada. Being chemically inert, scarce and sourced from isotopically distinct reservoirs, noble gases are ideal fluid tracers. Several isotopes are products of radioactive decay, opening opportunities of dating fluids on timescales going to a few years to billions of years. This research program represents a unique opportunity for young HQP to acquire a multi-disciplinary scientific, analytical and professional experience, in the study of the water cycle and its dynamic (behavior) in the continental crust, while specializing in a challenging and rewarding scientific discipline that is the noble gas geochemistry.

该研究计划将侧重于岩石圈流体的起源和演化及其在大陆地壳地球动力学演化中的关键作用。它将解决以下基本问题：i）跨地层流体流动的持续时间和长度及其在地壳脱气中的作用; ii）作为大陆地壳演化地质档案的化石水的存在; iii）具有经济意义的地壳流体，特别是地热流体和页岩气的成因和演化。 为实现这些目标，将在沉积和热液环境中开展一系列不同时空尺度的项目。一些重点将放在负责垂直迁移的过程中的气态物质（甲烷，氦.）在含水层，和大陆上的渗漏的成因，天然实验室是圣劳伦斯低地（QC）。研究的目的是量化甲烷通量，并模拟尤蒂卡页岩的运输过程。这些模型将被移植到寻求致密气开采的安蒂科斯蒂岛。将探讨的另一个重要方面是深层采矿环境中数亿至数十亿年前的流体的存在及其在Abitibi-Temiscamingue的凯迪拉克断层沿着矿化中的作用。在NSERC研究计划的同时，我们正在对墨西哥最大的活跃地热系统中的热液流体的演变进行详细研究，以评估其寿命和发电能力。这些热液环境是化石低温热液矿床的现代模拟。将获得的大型化学和同位素数据库对于了解这些环境中金属和流体来源之间的关系至关重要，这是未来矿床成因模型的前提。我们正在发展的关于地热系统的巨大和独特的专门知识也将用于研究加拿大一些省份的地热能力，特别是班夫地热区的成因。 追踪这些“地质流体”的起源和演变的方法是以保守元素即惰性气体的同位素为基础的，我在加拿大拥有这方面的独特专长。稀有气体具有化学惰性、稀缺性和来自同位素不同的储层，是理想的流体示踪剂。有几种同位素是放射性衰变的产物，这为在几年到几十亿年的时间尺度上测定流体的年代提供了机会。 该研究计划为年轻的HQP提供了一个独特的机会，可以获得多学科的科学，分析和专业经验，研究水循环及其在大陆地壳中的动态（行为），同时专门从事具有挑战性和有价值的科学学科，即惰性气体地球化学。