Advanced Seismic Imaging of Eastern Canadian Margins and Crustal Analogues

裂谷大陆边缘是由大陆岩石圈的伸展和破裂形成的，是地球板块构造周期的一个主要组成部分。它们还蕴藏着世界上主要的碳氢化合物资源。裂陷的性质因熔体的产生量而有很大的不同：从熔体很少或没有熔体的边缘（岩浆缺乏）到熔体大量的边缘（岩浆丰富）。这项提议的目的是通过成像在加拿大东部裂谷边缘形成的构造和在东南印度海岭形成的类似构造来研究裂谷过程的性质。在伸展过程中重建地壳和沉积物的几何形状，并将这些几何形状与理论模型原型进行比较，将有助于确定伸展过程的基本属性。要更好地理解大陆地壳变形的深度分布，洋陆过渡带和超低洋中脊的基底和地幔的性质，以及岩浆富和岩浆贫裂谷作用差异的原因，需要三个关键要素。现有图像可以定义边缘的基本整体结构，但这些图像中的特定区域或过渡往往定义不清。例如，洋陆过渡带可以呈现出复杂的结构，包括高度伸展的大陆地壳、暴露的地幔和薄的海洋地壳，这些结构很难用现有的数据来区分。这些复杂性对于提高对诸如大陆-海洋边界、破碎不整合和早期海洋海底扩张的性质等广泛持有的概念的理解至关重要。在大陆造山带，如阿尔卑斯山脉和加拿大北部科迪勒拉山脉，也发现了在类似的裂谷边缘环境中出土的地幔。因此，这些研究在广泛的地球基本过程中具有广泛的应用价值，对进一步了解海上油气资源的形成具有额外的应用价值。

Rifted continental margins form by extension and breakup of the continental lithosphere, as one major component of the Earth's plate tectonic cycle. They also contain major deposits of the world's hydrocarbon resources. The nature of rifting varies dramatically by the amount of melt produced: from margins with little or no melt (magma-poor) to margins with large volumes of melt (magma-rich). The purpose of this proposal is to investigate the nature of the rifting process by imaging structures formed across the rifted margins of eastern Canada and analogues of these structures on the Southeast Indian Ridge. Reconstructing the geometry of the crust and sediment throughout their extensional histories and comparing these geometries with theoretical model archetypes will help to identify fundamental attributes of the extensional processes. Three key elements are to better understand: i) the depth-dependent distribution of continental crustal deformation, ii) the nature of basement and mantle within the ocean-continent transition zone and on ultraslow mid-ocean ridges, and iii) the cause of variations between magma-rich and magma-poor rifting. Existing images can define the basic overall structure of margins but specific regions or transitions within such images are often poorly defined. For instance, the ocean-continent transition zone can exhibit complex structures, including highly extended continental crust, exposed mantle and thin oceanic crust, which are difficult to distinguish with existing data. These complexities are critically important for an improved understanding of such widely-held concepts as the continent-ocean boundary, the breakup unconformity, and the nature of early oceanic seafloor spreading. Occurrences of exhumed mantle in similar rifted margin settings have also been recognized in continental orogens, such as the Alps and the northern Canadian Cordillera. These studies thus have broad application to a wide range of fundamental Earth processes with additional applied value to further understanding the formation of offshore hydrocarbon resources.