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

SIEDCAR(与里奥格兰德裂谷相关的边缘驱动对流的地震调查)是部署在大平原西部边缘的75台宽带地震仪的2D阵列。SIEDCAR的设计目的是确定大平原边缘、里奥格兰德裂谷带以东的小范围边缘驱动对流是否正在发生，如果是，它的横向尺寸是什么。SIEDCAR的提案没有包括为地球动力学建模部分提供资金的请求，以解决其另外两个问题：1)什么条件导致边缘驱动对流；2)边缘驱动对流的构造(表面)影响是什么(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，但它被皮？S、审查员和项目官员视为SIEDCAR提案的关键组成部分。本提案旨在为SIEDCAR的地球动力学模拟部分寻求资金，并与SIEDCAR PI Pulliam和Gland合作开发。数值实验表明，岩石圈厚度的突然变化可以对上地幔流动产生深远影响。在岩石圈的不连续面处有一股下流，在较薄的岩石圈下方有一股上涌。地幔中的这种小规模对流(边缘驱动对流)是否是一种重要的真实世界现象，如果是，对地表地质的影响是什么，目前尚不清楚。SIEDCAR将提供沿大平原边缘的上地幔断层图像，那里可能发生边缘驱动对流。我们的目标是回答以下问题：1)关于边缘驱动对流过程：边缘驱动对流发生在什么时候？什么流变学或其他参数会影响这一过程？边缘驱动对流在3D中是什么样子的？岩石圈的哪一部分可能脱离并沉入软流圈(仅限于地幔岩石圈或下地壳？)什么是表面效应？预计在哪里(如果有)部分熔化？2)关于SIEDCAR拍摄的快速结构：这个快速结构与边缘驱动对流有关吗？快速异常的性质是什么？3)关于地壳和地表效应：边缘驱动对流如何与新墨西哥州东南部的构造、表面过程(垂直运动)和火山活动有关？我们将使用数值软件Citcom对边缘驱动对流进行地球动力学模拟研究。此外，我们的博士生将进行波形建模，以验证和校准之前产生的断层扫描。我们建议的研究将与SIEDCAR重叠一年。10名高中教师参加了SIEDCAR现场和数据分析工作和研讨会。SIEDCAR项目包括一个组成部分，为德克萨斯州和新墨西哥州的少数族裔教师提供现场和数据分析经验，并与旨在增加地球科学多样性的单独E&A；O项目合作。通过与德克萨斯大学奥斯汀分校的GeoFORCE德克萨斯州公私财团合作，以及为少数族裔服务的K-12科学教育工作者通过专业发展加强多样性途径的项目(由NSF的地球科学机会增强(OEDG)计划资助)，我们访问了德克萨斯州地区卓越科学教育合作组织，以招聘高中教师。SIEDCAR项目汇聚了一支热情、敬业的教师队伍。我们建议将该计划再延长一个暑期，以便在教师讲习班中增加地球动力学部分，并确保最终产品最终定稿：有条不紊、有据可查。因此，我们建议在本项目的第一年为十名教师举办一个为期十天的研讨会，作为SIEDCAR研讨会的后续活动。这些课程将组织良好，文件完整，内容齐全，并将广泛分发给感兴趣的教师。它们将与SIEDCAR PI合作执行。

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.