Whole-mantle body-wave tomography under the hotspot of La Réunion

留尼汪岛热点下的全地幔体波断层扫描

• 批准号: 247995824
• 负责人: Professor Dr. Heiner Igel
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/247995824?language=en
• 关键词: Whole; mantle; body; wave; tomography

The island of La Reunion is one of the most active and long-Iived volcanoes in the world. Its time- progressive, 5500-km long hotspot track emerges from the Deccan Traps of India, one of the largest flood basalt provinces on earth, which had a massive impact on global climate and life when they erupted. We want to establish the heat source and "plumbing system" that has been fueling this powerful hotspot for 65 million years. Through the RHUM-RUM project, a German- French effort funded mainly by the DFG and the ANR, we have deployed more than 90 broadband, ocean-bottom and Sand seismometers across the western Indian Ocean since 2011.The goal of RHUM-RUM is to seismically image a mantle plume - or lack of plume - from the surface down to the core-mantle boundary, and to understand the results in terms of material and heat flow. This comprises vertically ascending flow in the plume conduit, as well as any lateral flow spreading into the upper mantle of the western Indian Ocean. Here we are asking for funding for a Ph.D. Student to work the acquired waveform data into three-dimensional, whole-mantle P- and S-wave models of the mantle. We will be using multi-frequency tomography, a state-of-the art waveform Inversion method. Technical novelties or near-novelties include(i) the fully finite-frequency processing and Inversion of ocean-bottom and island seismograms across the entire usable frequency range of body waves.(ii) embedding of the RHUM-RUM data into a hemisphere-scale, whole-mantle model by joint Inversion with all other broadband data available for the hemisphere.(iii) the inclusion of core-diffracted waves, thanks to fully numerical waveform modeling. The goal is a significant improvement in structure of the lowermost mantle, the presumed footing region of deep mantle plumes.

留尼汪岛是世界上最活跃、最长寿的火山之一。它的时间进步，5500公里长的热点轨道出现在印度的德干陷阱，印度是地球上最大的洪水玄武岩省份之一，当它们喷发时，对全球气候和生活产生了巨大影响。我们想要建立热源和“管道系统”，它为这个强大的热点地区提供了6500万年的燃料。通过主要由DFG和ANR资助的德法合作项目-Rhum-Rum项目，自2011年以来，我们已经在西印度洋部署了90多台宽带海底和沙子地震仪。Rhum-Rum的目标是从地震角度成像从地表到核-地幔边界的地幔热柱-或没有地幔热柱，并从物质和热流的角度了解结果。这包括羽流管道中的垂直上升流，以及任何向西印度洋上地幔扩散的侧向流。在这里，我们申请资助一名博士生，将获得的波形数据转换成三维的、全地幔P波和S波模型。我们将使用多频率层析成像，这是一种最先进的波形反演方法。技术创新或近乎创新包括：(1)在整个体波可用频率范围内对海底和岛屿地震记录进行完全有限频率的处理和反演。(2)通过与半球现有的所有其他宽带数据联合反演，将Rhum-rum数据嵌入到半球尺度的全地幔模型中。(3)由于全数字波形模拟，包括了岩心绕射波。目标是显著改善最低地幔的结构，这是深部地幔羽流的假定落脚区。