An Investigation into Thermochemical Piles beneath Africa and the Pacific

对非洲和太平洋海底热化学桩的调查

• 批准号: 0510383
• 负责人: Allen McNamara
• 金额: $ 19.99万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0510383&HistoricalAwards=false
• 关键词: Investigation; into; Thermochemical; Piles; beneath

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 [phone] FAX [phone]Upcoming 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

地震学研究揭示了非洲和太平洋下方的下地幔中存在大型低速异常，并且越来越多的证据表明这些异常可能是由化学不均匀性引起的，可能是由于更致密的地幔成分造成的。将通过对类地对流强度（包括地球白垩纪至今的俯冲历史）进行完全 3D 球形热化学对流计算，对下地幔热化学堆的发育进行全面的地球动力学研究。所提出的工作涉及联合地球动力学-断层扫描方法，通过直接比较地球动力学预测和地震观测断层扫描来对异质地幔模型施加约束。这项工作的目标是：(1) 开发一种“层析成像过滤”和空间关联方法，将地球动力学输出转换为更接近观测层析成像的预期结果。(2) 通过确定等化学模型是否可以预测地震学观测结果来研究热化学模型的必要性。之前的工作已经暗示这不太可能，然而，只观察到了有限的参数集。（3）进行全面的参数搜索，以了解流变学、热力学和材料特性如何影响致密热化学堆的地理位置、面积范围和高度。（4）最终对被提议位于非洲和非洲下方的致密堆的密度和体积进行限制。 与这项工作相关的更广泛的影响包括向 GEON 项目提供结果数据，该项目一直积极开发新的交互式方法来可视化 3D 地球动力学数据集，其最终目标是促进科学和教育方面的合作。此外，新代码的开发将与地球动力学计算基础设施（CIG）共享。拟议的研究也将构成博士学位的基础。学生的论文，并将涉及地震学和地球动力学之间的合作。-- Robin Reichlin 地球物理学项目主任 National Science Foundation 4201 Wilson Blvd., Room 785 Arlington, VA 22230 电话 [phone] 传真 [phone]即将截止日期：地球物理学：2004 年 12 月 1 日（NEW EAR 计划公告 NSF 04-613)http://www.nsf.gov/pubsys/ods/getpub.cfm?nsf04613CSEDI：2005 年 8 月 25 日（计划公告 NSF 04-593） http://www.nsf.gov/pubs/2004/nsf04593/nsf04593.htmGuidelines：NSF 最新的拨款提案指南为 NSF 04-23 http://www.nsf.gov/pubsys/ods/getpub.cfm?gpg