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

在过去10-15年中，由于区域和国家倡议安装地震台站网络以记录地震信号，北美大陆大部分地区的地震数据覆盖率显著增加。这些台站记录的全球地震的地震波提供了关于地球结构的丰富信息，因为它们的速度取决于它们所经过的岩石的性质。到目前为止，我的研究主要集中在建立北美中部、东部和北部地区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，使用一种创新的方法，明确地探索温度和化学成分的变化，这些特性仅从地震数据很难区分出来。我的研究小组和我将整合各种各样的数据集，包括地球物理(地震学、地形学、重力和热流)和地球化学(岩石成分全球数据库和加拿大盾数据)测量，以模拟这些构造变化。我们还将为这些数据集提供新的高分辨率地震模型。加拿大周边的近海地区过去一直受到数据覆盖率较低的影响，阻碍了理解大陆裂谷和解体的努力。为了解决这个问题，我将积极参与在一个新的国家海洋地震学设施中安装海底地震仪的实验，重点是圣劳伦斯山谷和巴芬湾。总体而言，我的计划将包括5名研究生和1名博士后的研究项目，以及适合本科生的较小项目。这项新的研究计划将为大陆如何形成以及它们如何随着地质时间的推移而演变提供重要的见解。地震和热/化学模型提供了当今大陆结构的“快照”，将与地球化学测量结合使用，以更好地了解大陆的地质历史。除了回答有关地球演化的基本问题外，我提议的研究计划还将解决与在加拿大中部和东部勘探自然资源有关的问题，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侧重于地质测绘和浅层地球物理研究，但对“矿物系统”勘探方法的兴趣正在增加，在这种方法中，对大规模地壳和上地幔结构的基本了解提供了关于控制重要经济矿物的演化和就位过程的关键信息。我的新的地壳和上地幔的热/化学模型将对这一发展中的探索范式具有重要意义。

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.