Advanced Seismic Imaging of Eastern Canadian Margins and Crustal Analogues

加拿大东部边缘和地壳类似物的高级地震成像

• 批准号: 8459-2012
• 负责人: Louden, Keith
• 金额: $ 1.97万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568592
• 关键词: Advanced; Seismic; Imaging; Eastern; Canadian

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.

大陆岩石圈的扩展和破裂形成了裂痕的大陆边缘，这是地球板块构造循环的主要组成部分。它们还包含世界碳氢化合物资源的主要存款。裂谷的性质因产生的熔体量而大不相同：从几乎没有或没有熔体的边缘（岩浆贫民）到融化量大的边缘（岩浆富含岩浆）。该提议的目的是通过在加拿大东部的裂痕边缘和印度山脊东南部的这些结构的类似物中形成的成像结构来研究裂谷过程的性质。在整个延伸历史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识别扩展过程的基本属性。三个关键要素是更好地理解：i）大陆地壳变形的深度依赖性分布，ii）在海洋 - 陆地过渡区和超声东部山脊上的地下室和地幔的性质，以及iii）岩浆富裕和岩浆偏见之间变化的原因。现有图像可以定义边缘的基本总体结构，但是这些图像中特定的区域或过渡通常定义很差。例如，海洋过渡区可以表现出复杂的结构，包括高度扩展的大陆壳，暴露的地幔和薄的海洋外壳，这些结构很难用现有数据来区分。这些复杂性对于对广泛持有的概念的理解至关重要，例如大陆 - 海界，分手不整合以及早期海洋海底扩散的性质。在类似的裂痕边缘环境中，在大陆烤树木（例如阿尔卑斯山和加拿大北部山内利拉）中也认识到挖掘地幔的发生。因此，这些研究广泛地应用于广泛的基本地球过程，并具有额外的应用价值，以进一步理解离岸碳氢化合物资源的形成。