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、寿命最长的火山之一。它的时间递进，5500公里长的热点轨迹出现在印度的德干暗色岩中，这是地球上最大的洪水玄武岩省之一，当它们爆发时，对全球气候和生命产生了巨大的影响。我们想要建立一个热源和“管道系统”，它已经为这个强大的热点提供了6500万年的燃料。通过rham - rum项目，一个主要由DFG和ANR资助的德法合作项目，自2011年以来，我们已经在西印度洋部署了90多个宽带、海底和沙滩地震仪。rum - rum的目标是从地表到地核-地幔边界的地幔柱（或没有地幔柱）的地震成像，并从物质和热流的角度了解结果。这包括地幔柱导管中垂直上升的流动，以及任何向西印度洋上地幔扩散的横向流动。在这里，我们正在为一名博士生申请资金，将获得的波形数据转化为地幔的三维、全地幔P波和s波模型。我们将使用多频断层扫描，一种最先进的波形反演方法。技术上的新颖或近乎新颖包括(i)在整个体波可用频率范围内对海底和岛屿地震图进行完全有限频率的处理和反演。（ii）通过与所有其他半球可用的宽带数据联合反演，将rum - rum数据嵌入到半球尺度的全地幔模型中。（iii）由于采用了完整的数值波形模拟，包含了核心绕射波。目标是显著改善最下层地幔的结构，即假定的深部地幔柱的基础区域。