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

CSEDI：过渡带俯冲板片动力学：具有自洽状态方程的可压缩对流

• 批准号: 0855446
• 负责人: Scott King
• 金额: $ 25.37万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0855446&HistoricalAwards=false
• 关键词: CSEDI; Dynamics; Subducted; Slabs; Transition

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.

地震学家已经拍摄了俯冲带下各种几何形状的快速异常图像。这些异常被解释为变形的俯冲大洋岩石圈在某些位置位于过渡带的底部，而俯冲的大洋岩石圈穿过过渡带，而在其他位置几乎没有明显的阻力。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)如何影响俯冲海洋岩石圈的动力学和形态。虽然许多研究表明，俯冲洋壳的形态受表面板块边界的演化控制，但研究人员表明，过渡带的物质性质和相变也对俯冲物质的形态产生重大影响。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热力学上不一致的简化状态方程，要解决的第一个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(例如，板坯强度、过渡区克拉皮龙斜率、板坯年龄、板材速度、沟槽迁移)控制着从平卧板坯到贯通板坯的转变。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具体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指导，即哪些参数(S)对俯冲动力学具有最显著的影响。这将提供反馈，说明哪些参数应侧重于改进测量。这项提议将开发一个明确记录的、模块化的软件包，提供给定压力和温度下地幔材料的热力学性质。目标是使未来的研究人员能够在获得新信息时更新热力学数据库的元素，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。将开发这一软件，以便与当前和未来的地幔对流代码对接，并将通过地球动力学计算基础设施网站向研究界提供。