Seismic and thermochemical structure of the lithosphere: implications for continental evolution and resource potential

岩石圈的地震和热化学结构：对大陆演化和资源潜力的影响

• 批准号: RGPIN-2020-04682
• 负责人: Darbyshire, Fiona
• 金额: $ 3.13万
• 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: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740117
• 关键词: Seismic; thermochemical; structure; lithosphere; implications

In the last 10-15 years, there has been a remarkable increase in seismic data coverage over much of the North American continent, due to regional and national initiatives to install networks of seismograph stations to record earthquake signals. The seismic waves from global earthquakes, recorded at these stations, provide a wealth of information on Earth structure, as their speed depends on the nature of the rocks through which they travel. My research to date concentrated on establishing seismic models of the crust and upper mantle across regions of central, eastern and northern North America using a variety of methods to capture this structure. My proposed research program will investigate the crust and upper mantle of northern North America, in particular, the Canadian Shield and its surroundings, using an innovative approach that explicitly explores the variations in temperature and chemical composition, properties that are not readily distinguishable from seismic data alone. My research group and I will integrate a wide variety of data sets, including geophysical (seismology, topography, gravity and heat flow) and geochemical (global databases of rock composition and data from the Canadian Shield) measurements to model these structural variations. We will also contribute new high-resolution seismic models to these data sets. Offshore areas surrounding Canada have suffered from poor data coverage in the past, hampering efforts to understand continental rifting and breakup. To address this issue, I will be active in experiments involving ocean-bottom seismometer installations from a new national marine seismology facility, with a focus on the St. Lawrence valley and Baffin Bay. Overall, my program will include research projects for 5 graduate students and 1 postdoc, plus smaller projects suitable for undergraduates. The new research program will provide important insights into how continents are formed and how they evolve over geologic time. The seismic and thermal/chemical models provide a present-day "snapshot" of continental structure, which will be used in conjunction with geochemical measurements to understand better the geologic history of the continent. As well as answering fundamental questions about the Earth's evolution, my proposed research program will address issues related to the exploration for natural resources across central and eastern Canada where the most ancient crust is found. While much of the mineral exploration across Canada has traditionally focused on geologic mapping and shallow geophysical studies, interest is increasing in the "mineral systems" approach to exploration, where a fundamental understanding of large-scale crust and upper mantle structure provides key information on the processes that control the evolution and emplacement of economically important minerals. My new thermal/chemical models of the crust and upper mantle will be of significant importance to this developing exploration paradigm.

在过去 10-15 年中，由于区域和国家采取了安装地震台网络来记录地震信号的举措，北美大陆大部分地区的地震数据覆盖范围显着增加。这些站记录的来自全球地震的地震波提供了有关地球结构的丰富信息，因为它们的速度取决于它们所穿过的岩石的性质。迄今为止，我的研究集中于建立北美中部、东部和北部地区的地壳和上地幔的地震模型，使用各种方法来捕捉这种结构。我提出的研究计划将调查北美北部的地壳和上地幔，特别是加拿大地盾及其周围地区，采用创新方法，明确探索温度和化学成分的变化，以及与地震数据不易区分的特性独自的。我和我的研究小组将整合各种数据集，包括地球物理（地震学、地形、重力和热流）和地球化学（岩石成分的全球数据库和加拿大地盾数据）测量，以模拟这些结构变化。我们还将为这些数据集贡献新的高分辨率地震模型。过去，加拿大周边近海地区的数据覆盖范围很差，阻碍了了解大陆裂谷和分裂的努力。为了解决这个问题，我将积极参与在新的国家海洋地震学设施中安装海底地震仪的实验，重点是圣劳伦斯河谷和巴芬湾。总的来说，我的项目将包括 5 名研究生和 1 名博士后的研究项目，以及适合本科生的小型项目。新的研究计划将为了解大陆如何形成以及它们如何随地质时期演化提供重要见解。地震和热/化学模型提供了当今大陆结构的“快照”，它将与地球化学测量结合使用，以更好地了解该大陆的地质历史。除了回答有关地球演化的基本问题外，我提出的研究计划还将解决与加拿大中部和东部地区自然资源勘探相关的问题，那里发现了最古老的地壳。虽然加拿大各地的大部分矿产勘探传统上都集中在地质测绘和浅层地球物理研究上，但人们对“矿物系统”勘探方法的兴趣正在增加，其中对大尺度地壳和上地幔结构的基本了解提供了有关控制具有重要经济意义的矿物的演化和安置的过程。我的地壳和上地幔的新热/化学模型对于这种不断发展的探索范式具有重要意义。