Geodynamic models with thermodynamically self-consistent mineral physics

具有热力学自洽矿物物理的地球动力学模型

• 批准号: 41509765
• 负责人: Professor Dr. Hans-Peter Bunge, Ph.D.
• 金额: --
• 依托单位: Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik (BGI)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/41509765?language=en
• 关键词: Geodynamic; models; thermodynamically; self; consistent

We propose to combine geodynamic mantle modeling with thermodynamic models of mantle mineralogy in order to gain a better understanding of the thermal and elastic structure of Earth s mantle. For the geodynamic modeling we will use two dimensional (2-D) and three dimensional (3-D) mantle convection codes. For the thermodynamic mantle model we will apply the Gibbs-free-energy minimization method in order to compute mantle phase equilibria for a range of chemical mantle models. (1) temperature fields from mantle convection modeling will be postprocessed: we will assign to each Temperature (T) and Pressure (P) grid point value from the convection calculation its corresponding equilibrium mineral assemblage and physical properties. (2) We will then couple the convection and mineralogical model: we will use the density of the mineral assemblage to compute buoyancy forces (via the buoyancy term in the momentum equation) in the convection model. Thus densities derived from the mineralogical model establish convective flow and a thermal structure in the geodynamic model, while at the same time the P, T structure of the convection model is used in the computation of the equilibrium mineral assemblage. By combining the equation-of-state parameters with a shear wave model we will be able to study convection consistently with the underlying mineralogy. The proposed work will permit us to compare predictions of geodynamic mantle models directly to observed seismic properties. This is important because recent seismic studies of the mantle show results that are not easily understood in terms whole mantle convection. We will test the hypothesis that the seismic results can be attributed in part to complexities in the mineralogy. The mineralogical model will be made available for general use through a website, as a research and teaching tool for the geophysical and high pressure mineralogical community.

为了更好地了解地球地幔的热弹性结构，我们建议将地球动力学地幔模型与地幔矿物学的热力学模型结合起来。对于地球动力学建模，我们将使用二维（2-D）和三维（3-D）地幔对流代码。对于热力学地幔模型，我们将应用Gibbs-free-energy minimization方法来计算一系列化学地幔模型的地幔相平衡。(1)对地幔对流建模得到的温度场进行后处理：我们将对流计算得到的温度(T)和压力(P)网格点值赋给每个点对应的平衡矿物组合和物理性质。(2)然后，我们将耦合对流和矿物学模型：我们将使用矿物组合的密度来计算对流模型中的浮力（通过动量方程中的浮力项）。因此，由矿物学模型导出的密度在地球动力学模型中建立了对流流和热结构，同时利用对流模型的P、T结构计算平衡矿物组合。通过将状态方程参数与横波模型相结合，我们将能够与下伏矿物学一致地研究对流。提出的工作将使我们能够将地球动力学地幔模型的预测直接与观测到的地震特性进行比较。这一点很重要，因为最近对地幔的地震研究得出的结果不容易从整个地幔对流的角度来理解。我们将检验这样一个假设，即地震结果可以部分归因于矿物学的复杂性。矿物学模型将通过一个网站提供给一般使用，作为地球物理和高压矿物学界的研究和教学工具。