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Hudson Bay Lithospheric Experiment

哈德逊湾岩石圈实验

基本信息

批准号：
NE/D012317/1
负责人：
Michael Kendall
金额：
$ 43.46万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD012317%2F1
关键词：
Hudson Bay Lithospheric Experiment

项目摘要

The surface of the Earth is continually changing due to convection in the mantle and the movement of rigid plates (lithosphere) across its surface. Throughout Earth history the continents have been constantly migrating, being fused together and ripped apart. Nevertheless, at the heart of continents lies shield regions that have remained remarkably intact. Large continental roots lie beneath such cratonic regions and they are resistant to both thermal and mechanical alteration. How these roots are formed, what they are comprised of, and why they remain intact for so long are points of contentious debate. We propose a passive seismic experiment centred on the Preambrian core of North America, the largest Precambrian craton on Earth. Hudson Bay, which lies near the centre of this craton, is the site of the large positive deflection in the Earth's gravitational field. Despite being one of the most striking features of North America, the cause of the Hudson Bay intracratonic basin is not well understood. Gravity data and seismological images show that the mantle is anomalous in this region and various theories have been proposed to explain the anomaly. The southeast shore of Hudson Bay forms a nearly perfect arc of a semicircle and is called the Nastapoka Arc. It has been proposed that this arc is the signature of a huge meteorite impact crator, but this idea is speculative. Theories as to why such basins are formed and the nature of continental roots can be tested with a detailed seismological experiment. In collaboration with scientists in Canada and Germany we will deploy land and ocean-bottom seismometers for a two-year period, recording distant and local earthquakes. These data will be then used to study the velocity structure of the underlying mantle, the nature of mantle and lithospheric deformation and the formation of continental roots. We will test theories of the nature of the Nastapoka Arc. We will also look local seismicity in the region, which is anomalous and not well understood.

由于地幔中的对流和刚性板块（岩石圈）在其表面的运动，地球的表面不断变化。在整个地球历史中，大陆一直在不断迁移，融合在一起，撕裂。尽管如此，在大陆的中心，仍然存在着非常完整的盾牌区域。大型的大陆根位于这些火山区之下，它们对热和机械蚀变都有抵抗力。这些根是如何形成的，它们是由什么组成的，以及为什么它们能保持如此长的时间是有争议的争论点。我们提出了一个被动地震实验中心的北美，地球上最大的前寒武纪克拉通的前寒武纪核心。哈德逊湾位于克拉通中心附近，是地球引力场发生大的正偏转的地方。尽管哈德逊湾克拉通内盆地是北美最显著的特征之一，但其成因尚不清楚。重力资料和地震图象显示该区地幔存在异常，并提出了各种解释异常的理论。哈德逊湾的东南海岸形成了一个近乎完美的圆弧，被称为纳斯塔波卡弧。有人提出，这个弧形是一个巨大的陨石撞击crater的签名，但这个想法是推测性的。关于为什么会形成这样的盆地和大陆根的性质的理论可以通过详细的地震学实验来检验。我们将与加拿大和德国的科学家合作，部署陆地和海底地震仪，为期两年，记录远距离和当地的地震。这些数据将用于研究下伏地幔的速度结构、地幔和岩石圈变形的性质以及大陆根的形成。我们将测试纳斯塔波卡弧的性质的理论。我们还将研究该地区的局部地震活动，这是异常的，也不是很清楚。