An Investigation into Thermochemical Piles beneath Africa and the Pacific

地震学研究揭示了非洲和太平洋下地幔中存在大型低速异常，越来越多的证据表明，这些异常可能是由化学不均匀引起的，可能是由于更密集的地幔成分。对下地幔中热化学堆积的发展进行全面的地球动力学研究，将在类似地球的对流活力下进行全三维球面热化学对流计算，其中包括地球白垩纪至今的俯冲历史。建议的工作包括一种地球动力学-层析成像联合方法，通过地球动力学预测的层析成像与地震观测的层析成像之间的直接比较，对不均匀的地幔模型施加约束。这项工作的目标是：(1)发展一种“层析过滤”和空间相关的方法，将地球动力学输出转换成更接近观测层析成像的样子。(2)通过确定等化学模型是否可以预测来自地震学的观测，来研究热化学模型的必要性。然而，以前的工作已经暗示，这不太可能，然而，只有有限的参数集被观察到。(3)进行全面的参数搜索，以了解流变学、热力学和材料属性如何影响密集热化学堆的地理位置、面积和高度。(4)最终限制已被提议居住在非洲和太平洋下面的密集堆的密度和体积。与这项工作相关的广泛影响包括为GEON项目提供结果数据，该项目一直在积极开发新的、交互的方法来可视化3D地球动力学数据集，最终目标是促进科学和教育方面的合作。此外，新的代码开发将与地球动力学计算基础设施(CIG)共享。这项拟议的研究还将构成博士论文的基础，并将涉及地震学和地球动力学之间的合作。--罗宾·赖克林地球物理项目主任，国家科学基金会4201威尔逊大道，785室，阿灵顿，VA 22230电话(703)-2928556传真(703)-292-9025截止日期：地球物理学：2004年12月1日(新的EAR计划公告美国国家科学基金会04-613)http://www.nsf.gov/pubsys/ods/getpub.cfm?nsf04613CSEDI：8月25日，2005(计划公告NSF 04-593)http://www.nsf.gov/pubs/2004/nsf04593/nsf04593.htmGuidelines:NSF‘s最新的拨款建议指南是NSF 04-23 http://www.nsf.gov/pubsys/ods/getpub.cfm?gpg

Seismological studies have revealed the presence of large, low velocity anomaliesin the lower mantle beneath Africa and the Pacific, and there is growing evidence thatthese anomalies may be caused by chemical heterogeneity, possibly due to a more-densemantle component. A comprehensive geodynamical study into the development ofthermochemical piles in the lower mantle will be undertaken by performing fully 3Dspherical thermochemical convection calculations at Earth-like convective vigor whichincludes Earth's Cretaceous to present day subduction history. The proposed workinvolves a joint geodynamics-tomography approach to impose constraints uponheterogeneous mantle models by direct comparisons between geodynamically-predictedand seismically-observed tomography. The objectives of this work are to:(1) develop a method of 'tomographic filtering' and spatial correlation which willtransform geodynamic output to more closely resemble what it is expected toappear as from observational tomography.(2) Investigate the necessity of thermochemical models by determining whetherisochemical models can predict observations from seismology. Previous workhas hinted that this is not likely, however, only limited parameter sets havebeen observed.(3) To perform a comprehensive parameter search to understand how rheological,thermodynamic, and material properties affect the geographic position, arealextent, and height of dense thermochemical piles.(4) To ultimately place constraints upon the density and volume of dense pilesthat have been proposed to reside beneath Africa and the Pacific.Broader impacts associated with this work include providing resulting data to theGEON project which has been active in developing new, interactive methods to visualize3D geodynamical data sets with the ultimate goal of fostering collaborative efforts inscience and education. In addition, new code development will be shared with theComputational Infrastructure for Geodynamics (CIG). The proposed research will alsoform the basis of a Ph.D. student's dissertation, and will involve collaboration betweenseismology and geodynamics.-- Robin Reichlin Geophysics Program Director National Science Foundation 4201 Wilson Blvd., Room 785 Arlington, VA 22230 PHONE (703)-292-8556 FAX (703)-292-9025Upcoming Deadlines:GEOPHYSICS: December 1, 2004 (NEW EAR Program Announcement NSF 04-613)http://www.nsf.gov/pubsys/ods/getpub.cfm?nsf04613CSEDI: August 25, 2005 (Program Announcement NSF 04-593) http://www.nsf.gov/pubs/2004/nsf04593/nsf04593.htmGuidelines:NSF's latest Grant Proposal Guide is NSF 04-23 http://www.nsf.gov/pubsys/ods/getpub.cfm?gpg