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，这些板块在下方深层地幔的对流驱动下围绕地球表面移动。 变形和火山作用发生在板块边界处，相邻板块会聚、发散或相互滑过。 我的研究重点是现代发散和汇聚板块边界的过程。 板块因大陆裂谷而分裂，然后海底扩张。裂谷影响的区域可能相当广泛，在某些情况下，“失败”的裂谷盆地不会进展到海洋开口，而是搁浅在大陆架上。北大西洋有几个失败的裂谷盆地（圣女贞德、北海、罗卡尔、豪猪），其中一些盆地富含石油。 因此，板不是刚性的，特别是靠近其边缘的地方，我们需要考虑板内的拉伸变形。 在北大西洋板块重建项目中，我们将使用新型可变形板块模型，根据地震图像和其他数据来估计断层和地壳减薄引起的延伸随时间的变化。这些结果关系到基本的地球过程以及在盆地中寻找石油和天然气的前景。 板块沿着火山弧汇聚。在弧连接的地方，下部下降（“俯冲”）板块的撕裂可能会沿着“俯冲变换边缘传播器”（STEP）断层产生两个弧的偏移。 在地中海东部，由于希腊弧下方的下非洲板块俯冲向南“回滚”，希腊弧逐渐向塞浦路斯弧以南偏移。俯冲板块的撕裂是在与塞浦路斯岛弧交界处形成宽阔的STEP断层带的原因。 断层带有非常深的盆地（罗德和菲尼克盆地）和高海山（阿那克西曼德），所有这些都在活跃变形。 我的研究是制作并解释地震剖面变形图像。研究结果将有助于了解（i）与撕裂板块相关的构造过程，以及（ii）该地区的地震灾害。