GEODYNAMIC MODELING OF EDGE-DRIVEN CONVECTION IMAGED BY SIEDCAR (SEISMIC INVESTIGATION OF EDGE DRIVEN CONVECTION ASSOCIATED WITH THE RIO GRANDE RIFT)

SIEDCAR（与里约热内卢大裂谷相关的边缘驱动对流地震调查）是一个由75个宽带地震仪组成的二维阵列，部署在大平原西部边缘。SIEDCAR的设计目的是确定在b里约热内卢大裂谷带以东的大平原边缘是否发生了小规模的边缘驱动对流，如果发生了，那么它的横向尺寸是多少。SIEDCAR的提案不包括为地球动力学建模组件提供资金的请求，以解决另外两个问题：1)什么条件会导致边缘驱动对流，2)边缘驱动对流的构造（表面）效应是什么（如果有的话），以及它们如何与地质观测相匹配。虽然没有为地球动力学建模申请资金，但它被PI？(5)由评审人员和项目官员负责。本提案旨在为SIEDCAR的地球动力学建模组件寻求资金，并与SIEDCAR pi Pulliam和Grand合作开发。数值实验表明，岩石圈厚度的突变会对上地幔流动产生深远的影响。在岩石圈不连续处有一个下涌，在较薄的岩石圈下方有一个上涌。地幔中这种小规模的对流流动（边缘驱动的对流）是否是一个重要的、现实世界的现象，如果是，对地表地质的影响是什么，都是未知的。SIEDCAR将提供沿大平原边缘的上地幔的层析成像图像，据推测，边缘驱动的对流发生在那里。我们的提案的目的是回答以下问题：1)关于边缘驱动对流的过程：什么时候发生边缘驱动对流？什么流变学或其他参数影响这一过程？边缘驱动的对流在3D中是怎样的？岩石圈的哪一部分可能分离并沉入软流圈（仅是地幔岩石圈还是下地壳？）什么是表面效应？哪里（如果有的话）预计会部分熔化？2)对于SIEDCAR成像的快速构造：该快速构造是否与边缘驱动对流有关？高速异常的本质是什么？3)关于地壳和地表效应：边缘驱动的对流如何与新墨西哥州东南部的构造、地表过程（垂直运动）和火山活动相关？我们将使用数值软件Citcom进行边缘驱动对流的地球动力学模拟研究。此外，我们的博士生将做波形建模来验证和校准之前产生的断层扫描。我们提议的研究将与SIEDCAR重叠一年。10名高中教师参加了SIEDCAR的实地和数据分析工作和讲习班。SIEDCAR项目包括一个组成部分，与旨在增加地球科学多样性的单独的E&amp；O项目合作，为德克萨斯州和新墨西哥州的少数族裔教师提供实地和数据分析经验。通过与德克萨斯大学奥斯汀分校的GeoFORCE德州公共/私人财团合作，以及名为“通过为少数民族服务的K-12科学教育者的专业发展加强多样性途径”的项目（由美国国家科学基金会加强地球科学多样性的机会（OEDG）计划资助），我们进入了德克萨斯州卓越科学教育区域合作组织招募高中教师。SIEDCAR项目汇集了一支热情投入的强大教师队伍。我们建议将该项目再延长一个夏天，以便在教师研讨会中添加地球动力学成分，并确保最终产品最终确定：有组织且有充分的文件记录。因此，我们建议在该项目的第一年为10名教师举办一次为期10天的研讨会，这是继SIEDCAR研讨会之后的又一次研讨会。这些课程将被精心组织、充分记录和独立，并将广泛分发给感兴趣的教师。这些活动将与SIEDCAR pi合作进行。

SIEDCAR (Seismic Investigation of Edge driven Convection Associated with the Rio Grande Rift) is a 2D array of 75 broadband seismographs deployed along the western edge of the Great Plains. SIEDCAR was designed to determine whether small-scale, edge-driven convection is occurring along the edge of the Great Plains, east of the Rio Grande rift zone, and if so, what its lateral dimensions are. The SIEDCAR proposal did not include a request for funding for a geodynamic modeling component to address its two other questions: 1) what conditions lead to edge-driven convection, and 2) what (if any) are tectonic (surface) effects of edge-driven convection and how do they match geologic observations. Although no funding was requested for the Geodynamic Modeling, it was considered a critical component of the SIEDCAR proposal by the PI?s, by the reviewers, and by the Program Officer. The present proposal serves to pursue funding for the geodynamic modeling component of SIEDCAR, and was developed in collaboration with SIEDCAR PIs Pulliam and Grand.Numerical experiments show that an abrupt change in the thickness of the lithosphere can have a profound effect on upper mantle flow. There is a downwelling at the lithospheric discontinuity, and upwelling below the thinner lithosphere. Whether such small-scale convective flow (edge-driven convection) in the mantle is a significant, real world phenomenon and, if so, what the effects on surface geology are, is unknown. SIEDCAR will provide tomographic images of the upper mantle along the edge of the Great Plains, where edge-driven convection supposedly occurs.Our goal of this proposal is to answer the following questions: 1) Regarding the process of edge-driven convection: When does edge-driven convection occur? What rheological or other parameters influence this process? How does edge-driven convection look like in 3D? Which part of the lithosphere may detach and sink into the asthenosphere (only mantle lithosphere or also lower crust?) What are surface effects? Where (if any) is partial melting expected? 2) Regarding the fast-velocity structure imaged by SIEDCAR: Is this fast-velocity structure related to edge driven convection? What is the nature of the fast-velocity anomaly? 3) Regarding crustal and surface effects: How does edge-driven convection relate to tectonics, surface processes (vertical movements), and volcanism in southeastern New Mexico?We will use the numerical software Citcom for a Geodynamic Modeling study of edge-driven convection. In addition, our PhD student will do waveform modeling to validate and calibrate the tomography produced previously. Our proposed research would overlap one year with SIEDCAR.Ten High-school teachers have participated in SIEDCAR field and data analysis efforts and workshops. The SIEDCAR project includes a component that provides field and data analysis experiences for minority-serving teachers in Texas and New Mexico in collaboration with separate E&O projects that aim to increase diversity in the geosciences. By partnering with UT Austin's GeoFORCE Texas public/private consortium and the project entitled Strengthening Pathways to Diversity Through Professional Development for Minority-Serving K-12 Science Educators (funded by NSF's Opportunities for Enhancing Diversity in the Geosciences (OEDG) Program), we accessed the Texas Regional Collaboratives for Excellence in Science Education to recruit the high school teachers. The SIEDCAR project has assembled a strong cadre of teachers who are enthusiastic and engaged. We propose to extend the program by one more summer, in order to add a geodynamic component to the teacher workshops and to ensure that final products are finalized: organized and well-documented. We thus propose to conduct a single, ten-days workshop for ten teachers in year one of this project which follows up on a SIEDCAR workshop. These lessons will be well-organized, well-documented, and self-contained and will be broadly distributed to interested teachers. They will be performed in collaboration with the SIEDCAR PIs.