Structure of rifted continental margins and gas hydrates

大陆边缘是在大陆岩石圈解体时形成的，是地球板块构造旋回的重要组成部分。这项提议的目的是通过界定加拿大东部裂谷边缘形成的构造及其相关的边缘共轭来调查这一过程的性质。这些构造是通过将广角地震速度模型与深部多道反射数据相结合来确定的，以产生完整的深度剖面。我们最近在加拿大东部边缘地区收集了许多这样的资料。我将完成对这些数据的分析，并将它们与非洲西北部和欧洲西北部共轭边缘的类似剖面相结合。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。一个关键因素是了解大陆-海洋过渡带内基底和地幔的神秘性质。现有的地震模型表明，该带沿边缘走向可以表现出显著的变异性，可能与裂谷几何形状突然发生变化的调节带的位置有关。我将使用分辨率更高的新地震数据以及新的处理和建模程序来研究以前确定的加拿大近海和格陵兰岛两个这样的地区。大陆边缘还蕴藏着世界上主要的碳氢化合物资源，既有常规形式的深层油气藏，也有非常规形式的捕获在水合物结构中的浅层甲烷。如果释放到大气中，这种甲烷也可能成为温室气体的一个重要来源，有可能导致快速变暖。这项提案的第二个重点将是更好地定义加拿大东部近海水合物的性质，这些水合物最近才被发现。

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.