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Geodynamic modelling and tomographic visibility of a mantle plume under La Réunion

留尼汪岛地幔柱的地球动力学建模和层析可见性

基本信息

批准号：
247034637
负责人：
Professor Dr. Heiner Igel
金额：
--
依托单位：
Sektion 2.5: Geodynamische Modellierung
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/247034637?language=en
关键词：
Geodynamic modelling tomographic visibility mantle

项目摘要

The goal of the German-French experiment RHUM-RUM is to seismologically image a mantle plume - or its absence - under the hotspot of La Réunion, and to understand the results in terms of convective flow at all depth levels of the Earth mantle. Most of the ocean-bottom and island data will become available in late 2013.The work we propose here consists of two kinds of interrelated, a priori modeling studies, meant to accompany the data analysis components of RHUM-RUM. In Work Package 1 (one Ph.D. student) we propose to develop a new geodynamic model of the Réunion mantle plume interacting with large-scale flow, which is commonly considered to be largely driven by subducted slabs, but possibly also by active upwellings under Africa and the Indian Ocean. In Work Package 2 (one Ph.D. student), we will investigate the tomographic observability of such a priori reasonable plume structures.We propose a full-fledged parameter and uncertainty study a priori (Down to which threshold of each rheological / physical parameter should a plume still be detectable, at each depth?), rather than the very topical resolution tests that are typically shown a posteriori in order to justify a preferred model obtained from the real data. Our geodynamic models, and their expected tomographic signatures, can therefore be regarded as a true predictions. As observations become available from the RHUM-RUM data analyses by colleagues, the models will be compared to them, geodynamical parameters will be narrowed down, and modified models will be run. Both work packages contain strong components of computational method development, in terms of mantle convection simulations and broadband waveform inversion.Our overarching objectives are:1. Better geodynamical models in general, of the process of a hypothesized classical plume rising from a Large Low Shear wave Velocity Province (LLSVP) - a generation mechanism currently thought to apply to most oceanic hotspots. 2. A clear and comprehensive understanding of which structures, if present, could or could not be resolved by the actual RHUM-RUM data.3. An immediate geodynamical context for actually observed structures, once they become available, i.e., at a moment when the project experiences its maximum momentum and greatest interest from the scientific community.

德法实验RHUM-RUM的目标是对留尼旺岛热点下的地幔柱（或不存在地幔柱）进行地震成像，并了解地幔所有深度水平对流的结果。大多数海底和岛屿数据将在2013年底可用。我们在这里提出的工作包括两种相互关联的先验建模研究，旨在伴随RHUM-RUM的数据分析组件。学生），我们建议建立一个新的地球动力学模型的留尼汪地幔柱与大规模的流动，这是通常被认为是在很大程度上由俯冲板驱动，但也可能是由非洲和印度洋下的活跃隆升。在工作包2（一个博士学位。学生），我们将调查这种先验合理的羽流结构的层析可观测性。我们提出了一个成熟的参数和不确定性研究先验（下至每个流变/物理参数的阈值，羽流在每个深度仍然可以检测到？），而不是非常热门的分辨率测试，这些测试通常是事后证明的，以便证明从真实的数据中获得的首选模型的合理性。因此，我们的地球动力学模型及其预期的层析成像特征可以被视为真实的预测。随着同事们从RHUM-RUM数据分析中获得观测结果，将对模型进行比较，缩小地球动力学参数，并运行修改后的模型。这两个工作包都包含了计算方法发展的重要组成部分，包括地幔对流模拟和宽带波形反演。一般来说，更好的地球动力学模型描述了从大型低剪切波速度区（LLSVP）升起的假设经典羽流过程--目前认为这是适用于大多数海洋热点的生成机制。2.清楚全面地了解哪些结构（如果存在）可以或不能通过实际RHUM-RUM数据解决。一个直接的地球动力学背景下，实际观察到的结构，一旦他们成为可用的，即，在该项目经历其最大的势头和科学界最大的兴趣的时刻。