Forward modelling of mantle density anomalies from geodynamic considerations

从地球动力学角度考虑地幔密度异常的正演模型

• 批准号: 30265607
• 负责人: Professor Dr. Hans-Peter Bunge, Ph.D.
• 金额: --
• 依托单位: Department für Geo- und Umweltwissenschaften
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/30265607?language=en
• 关键词: Forward; modelling; mantle; density; anomalies

We propose a detailed mass budget analysis of the solid Earth, that is mantle and lithosphere, from geodynamic a-priori considerations. For the lithosphere and upper mantle, we will build on a published 3-D density model (3SMAC, Nataf and Ricard [1996]). For the deeper mantle, we will infer thermally induced density anomalies from a history of plate motion assimilated in global mantle circulation models. Key advances to the mantle convection model include (1) a thermodynamically self-consistent formulation of the mantle mineralogy and (2) a very high numerical resolution sufficient to resolve (for the first time) global mantle flow at Earthlike convective vigor. The benefit of the latter is to resolve thermal boundary layers at time-and length-scales appropriate for Earth¿s mantle. We will use the forward models to gain better insight on the impact of hot thermal upwellings on the mantle density budget. This is important because recent geodynamic studies have favored a larger heat flux across the core mantle boundary than prior estimates. We will test the sensitivity of mantle density models to a range of core heat flux values.

我们从地球动力学的先验考虑出发，提出了固体地球（即地幔和岩石圈）的详细质量预算分析。对于岩石圈和上地幔，我们将以已发表的三维密度模型（3SMAC， Nataf和Ricard[1996]）为基础。对于较深的地幔，我们将从全球地幔环流模型中吸收的板块运动历史推断热致密度异常。地幔对流模型的关键进展包括：(1)地幔矿物学的热力学自一致公式；(2)非常高的数值分辨率，足以（首次）以类似地球的对流活力来解析全球地幔流动。后者的好处是在适合于地幔的时间和长度尺度上解析热边界层。我们将使用正演模型来更好地了解热上升流对地幔密度收支的影响。这一点很重要，因为最近的地球动力学研究表明，穿过地核地幔边界的热通量比先前估计的要大。我们将测试地幔密度模型对一系列核心热通量值的敏感性。