Structure of rifted continental margins and gas hydrates

裂谷大陆边缘是在大陆岩石圈分裂期间形成的，是地球板块构造周期的主要组成部分。本提案的目的是通过定义横跨加拿大东部裂谷边缘及其相关边缘共轭形成的结构来研究这一过程的性质。这些构造是通过将广角地震速度模型与深部多通道反射数据相结合来确定的，从而得出综合深度剖面。我们最近在加拿大东部边缘地区收集了一些这样的概况。我将完成对这些数据的分析，并将它们与横跨西北非洲和西北欧洲共轭边缘的类似概况相结合。重建大陆伸展过程中地壳和沉积物的几何形状，并与最近的理论模型进行比较，将有助于确定伸展过程的基本属性。一个关键的因素是要了解大陆-海洋过渡区内基底和地幔的神秘性质。现有的地震模型表明，该带沿边缘走向表现出明显的变异性，这可能与裂谷几何形状突变的容纳带位置有关。我将使用新的地震数据和新的处理和建模程序，研究先前确定的加拿大近海和格陵兰岛的两个这样的区域。大陆边缘还蕴藏着世界上主要的碳氢化合物资源，既有传统形式的深层油气储层，也有非常规形式的浅层甲烷水合物储层。如果释放到大气中，这些甲烷也可能形成一种强有力的温室气体来源，可能导致气候迅速变暖。该提案的第二个重点将是更好地定义加拿大东部水合物的性质，这是最近才确定的。

Rifted continental margins form during breakup of the continental lithosphere, as a major part of the Earth's plate tectonic cycle. The purpose of this proposal is to investigate the nature of this process by defining structures formed across the rifted margins of eastern Canada and their associated margin conjugates. These structures are determined by combining wide-angle seismic velocity models with deep multi-channel reflection data to produce integrated depth profiles. We have recently collected a number of such profiles across the eastern Canadian margins. I will complete the analysis of these data and combine them with similar profiles across the conjugate margins of NW Africa and NW Europe. Reconstructing the geometry of the crust and sediment during continental extension and comparison with recent theoretical models will help to identify fundamental attributes of the extensional processes. A key element is to understand the enigmatic nature of basement and mantle within the continent-ocean transition zone. Existing seismic models indicate that this zone can exhibit significant variability along strike of the margin, possibly related to the location of accommodation zones where rifting geometries suddenly change. I will study two such regions previously identified offshore Canada and Greenland using new seismic data with improved resolution and new processing and modeling procedures. Continental margins also contain major deposits of the world's hydrocarbon resources, both in conventional form as deep oil and gas reservoirs and in unconventional form as shallow methane trapped in hydrate structures. If released to the atmosphere, this methane could also form a potent source of greenhouse gas, potentially resulting in rapid warming. A second focus of this proposal will be to better define the nature of hydrates off eastern Canada, which have only recently been identified.