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裂解形成的，是地球板块构造旋回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。裂谷作用的性质因产生的熔融量不同而有很大不同：从很少或没有熔融的边缘(岩浆贫乏)到边缘有大量熔融(富含岩浆)。这项提议的目的是通过成像横跨加拿大东部裂谷边缘形成的构造和东南印度洋海脊上这些构造的类似物来研究裂谷过程的性质。重建地壳和沉积物在整个伸展历史中的几何形状，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。有三个关键因素需要更好地理解：i)大陆地壳形变随深度的分布，ii)大洋-大陆过渡带和超低洋中脊内基底和地幔的性质，以及iii)富岩浆裂谷作用和贫岩浆裂谷作用之间差异的原因。现有图像可以定义页边距的基本整体结构，但此类图像中的特定区域或过渡通常定义不佳。例如，大洋-大陆过渡带可能表现出复杂的结构，包括高度伸展的陆壳、裸露的地幔和薄的洋壳，这些结构很难与现有数据区分开来。这些复杂性对于更好地理解诸如大陆-海洋边界、裂解不整合和早期大洋海底扩张的性质等广泛存在的概念至关重要。在大陆造山带，如阿尔卑斯山和加拿大北部的科迪莱拉，也发现了类似裂谷边缘环境中的地幔出土。因此，这些研究对广泛的基本地球过程具有广泛的应用价值，对于进一步了解近海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.