CSEDI: Dynamics of Subducted Slabs in the Transition Zone: Compressible Convection with Self-Consistent Equation of State

地震学家对俯冲带下的各种几何形状快速异常进行了成像。这些异常被解释为在某些位置变形的洋俯冲岩石圈位于过渡带底部之上，而在其他位置洋俯冲岩石圈以很小的明显阻力穿过过渡带。研究人员将研究状态方程（即密度作为压力、温度和成分的函数）如何影响俯冲的海洋岩石圈的动力学和形态。虽然许多研究表明，洋壳俯冲形态受表面板块边界演化的控制，但研究人员发现，过渡带的物质性质和相变化对俯冲物质形态也有重要影响。这项研究将把矿物性质的实验室测量与地幔对流计算结合起来。大多数可压缩对流计算目前使用的是一种简化的状态方程，它在热力学上是不一致的，而将要解决的第一阶问题是，何时以及是否有理由使用简单的状态方程。第二个问题是，哪些参数（如板强度、过渡带克拉珀龙坡相转变、板龄、板速度、沟移）控制着平卧板向穿透板的转变。这项工作的第三个组成部分是评估热力学数据库中哪些矿物和特定参数对俯冲动力学有最显著的影响。这为矿物物理研究界提供了关于哪些参数对俯冲动力学影响最大的指导。这将提供关于哪些参数需要重点改进测量的反馈。该提案将开发一个清晰的文档化、模块化的软件包，该软件包将提供地幔材料在给定压力和温度下的热力学特性。目标是使未来的研究人员能够更新热力学数据库的元素，因为新的信息变得可用，或通过系统地改变热力学数据库的特定元素来进行参数研究调查。该软件将被开发用于与当前和未来的地幔对流代码接口，并将通过地球动力学计算基础设施网站提供给研究界。

Seismologists have imaged a variety of geometries fast anomalies beneath subduction zones. These anomalies have been interpreted as deformed subducted oceanic lithosphere lying atop the base of the transition zone at some locations and subducted oceanic lithosphere traversing the transition zone with little apparent resistance at other locations. The investigators will investigate how the equation of state (i.e., density as a function of pressure, temperature, and composition) impacts the dynamics and morphology of subducted oceanic lithosphere. While a number of studies have shown that the morphology of subducted oceanic crust is controlled by the evolution of the plate boundary at the surface, the investigators have shown that the material properties and phase changes in the transition zone also have a significant impact on the morphology of subducted material. This research will bring together laboratory measurements of mineral properties with mantle convection calculations. Most compressible convection calculations currently use a simplified equation of state that is thermodynamically inconsistent and the first-order question that will be addressed is when and whether it is justified to use a simple equation of state. A second question is which parameters (e.g., slab strength, Clapyron slope of the transition zone phase transformations, slab age, plate velocity, trench migration) control the transition from flat lying slabs to penetrating slabs. The third component of this work is to assess which minerals and specific parameters in the thermodynamic database have the most significant effect on the dynamics of subduction. This provides guidance to the mineral physics research community as to which parameter(s) have the most significant influence on the dynamics of subduction. This will provide feedback as to which parameters to focus on improving measurements. This proposal will develop a clearly documented, modular, software package that will provide the thermodynamic properties of a mantle material at a given pressure and temperature. The goal is to enable future researchers to update elements of the thermodynamic database as new information becomes available or to perform parameter study investigations by systematically changing specific elements of the thermodynamic database. This software will be developed to interface with current and future mantle convection codes and will be made available to the research community through the Computational Infrastructure for Geodynamics website.