Seismological studies of the evolution of young plate margins and associated basins

年轻板块边缘及相关盆地演化的地震学研究

• 批准号: 36592-2012
• 负责人: Hall, Jeremy
• 金额: $ 3.35万
• 依托单位: Memorial University of Newfoundland
• 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=568754
• 关键词: Seismological; studies; evolution; young; plate

The top 100-200 km of the solid Earth consists of a small number of (more or less) rigid 'plates', which move around Earth's surface driven by convection in the deep mantle below. Deformation and volcanism occur at plate boundaries, where adjacent plates converge, diverge or slide past one another. My research is focussed on processes at modern divergent and convergent plate boundaries. Plates diverge by continental rifting and then seafloor spreading. The rifting affects a region which may be quite wide and, in some cases, 'failed' rift basins, which do not progress to ocean opening, are left stranded on the continental shelves. In the North Atlantic there are several failed rift basins (Jeanne d'Arc, North Sea, Rockall, Porcupine) some of which are petroliferous. So, the plates are NOT rigid, especially close to their margins, and we need to account for the within-plate extensional deformation. We will estimate the variation of extension with time from faults and crustal thinning, determined from seismic images and other data, in a North Atlantic Plate Reconstruction Project using a novel deformable plate model. The results bear on fundamental Earth processes and on the prospects for finding oil and gas in the basins. Plates converge along volcanic arcs. Where arcs join, a tear in the lower, descending ('subducting') plate may produce an offset of the two arcs along a 'Subduction Transform Edge Propagator' (STEP) fault. In the eastern Mediterranean, the Hellenic arc is increasingly offset to the south of the Cyprus arc, because of the southerly 'rollback' of subduction of the lower African plate below the Hellenic arc. The causative tear in the subducting plate is responsible for a wide STEP fault zone at the junction with the Cyprus arc. The fault zone has very deep basins (Rhodes and Finike basins) and high seamounts (Anaximander) all actively deforming. My research is to make, and interpret, images of the deformation from seismic profiling. The results will aid understanding of (i) the tectonic processes associated with tearing plates, and (ii) earthquake hazards in the region.

固体地球的顶部100 - 200公里由少量（或多或少）刚性“板块”组成，这些板块在下面地幔深处的对流驱动下围绕地球表面移动。 变形和火山活动发生在板块边界，在那里相邻的板块会聚，分开或滑动过去。 我的研究主要集中在现代板块边界的发散和收敛过程。 板块通过大陆裂谷和海底扩张而分开。裂谷影响的区域可能相当广泛，在某些情况下，“失败”的裂谷盆地，没有进展到海洋开放，被困在大陆架上。在北大西洋有几个失败的裂谷盆地（Jeanne d'Arc，北海，Rockall，Porcupine），其中一些是含油的。 因此，板块并不是刚性的，特别是靠近它们的边缘，我们需要考虑板块内部的伸展变形。 在北大西洋板块重建项目中，我们将使用一种新的可变形板块模型，从地震图像和其他数据中确定断层和地壳减薄，估计伸展随时间的变化。这些结果关系到基本的地球过程和在盆地中寻找石油和天然气的前景。 板块沿着火山弧会聚。在弧连接处，较低的下降（"俯冲"）板块的撕裂可能会产生两个弧沿着"俯冲转换边缘断层"（STEP）的偏移。 在地中海东部，希腊弧越来越多地向塞浦路斯弧的南部偏移，这是由于下非洲板块俯冲到希腊弧下方的向南“回滚”。俯冲板块中的成因撕裂是在与塞浦路斯弧交界处形成宽STEP断层带的原因。 断裂带有非常深的盆地（罗兹和菲尼凯盆地）和高海山（阿那克西曼德），所有这些盆地都在积极变形。 我的研究是制作和解释地震剖面的变形图像。这些结果将有助于理解（i）与板块撕裂相关的构造过程，以及（ii）该地区的地震灾害。