Constraining Rifting and Magmatism in the West Antarctic Rift using Geodynamic Modeling

非技术项目描述该项目使用计算机模型来调查在过去1亿年中控制西南极裂谷系统（WARS）形成的过程，WARS是世界上最大的大陆裂谷带之一。WARS的一个神秘特征是它从早期历史上的广泛裂谷系统过渡到最近的狭窄裂谷。宽的和窄的裂缝都是地球上常见的特征。拟议的研究利用WARS的独特行为来研究决定这些裂缝行为如何以及为什么发展的因素。将开发计算机模型，以匹配WARS中的伸展方式与裂谷中火山活动和岩浆活动的时空模式。这些模型将限制裂谷下地壳和地幔的温度，这被认为是对裂谷行为的风格施加强有力的控制，并将测试裂谷相关的岩浆活动的原因的几个假设。该项目有助于通过更好地了解大陆如何分裂以及大陆裂谷和裂谷沉积盆地如何演变来推进基础科学。对这些过程的更好理解提供了基础知识，为现代裂谷系统中常见的火山，地震和滑坡灾害的评估提供了信息，例如美国西部的宽山脉裂谷和狭窄的东非裂谷。项目成果还将提供一个基于过程的地质背景，用于勘探活动裂谷中的地热能资源和古代裂谷系统形成的沉积盆地中的化石能源资源，例如美国东部和墨西哥湾大陆边缘的边界。在这个项目期间进行的研究将成为一个动手的科学实验，旨在证明初中和高中科学课的裂痕行为的发展的基础。包含实验材料的科学工具包将被创建并添加到K-12科学材料中？借阅图书馆？由科罗拉多州立大学（CSU）维护。K-12教师将在CSU校园定期举办的暑期教师研讨会上接受使用科学工具包的培训。这项研究将在一位博士的帮助下进行。学生和一个本科生，他们都将参加K-12教师？的讲习班和课堂科学套件的发展。技术项目描述这个项目将产生新的制约下，地球的地幔热演化的西南极裂谷系统（WARS），因为开始的扩展ca。一亿零五百万年前。这对于理解WARS延伸至关重要，因为对比模型认为，主动裂谷是由上升的热地幔柱驱动的，被动裂谷是由板内重力和构造板块边缘施加的远场边界力驱动的。将开发一套有限元模型，以检查替代裂谷的情况下，以确定模型与热地幔是一致的WARS结构演变。将创建多个模拟，以确定最温暖和最冷的裂谷情景。这些温暖和凉爽的端元温度场将被用来测试的假设，一个或多个羽流是负责裂谷在战争。通过使用端元模型的P-T场计算每个假设来源的潜在岩浆贡献，将对裂谷相关岩浆作用的各种成岩模型进行测试。该项目将产生两个自洽模型的裂谷和岩浆作用的战争（温暖和冷端成员），由匹配的裂谷和岩浆生产和成分的时空模式的结构演化的双重要求的约束。

Nontechnical Project DescriptionThis project uses computer models to investigate the processes that controlled formation of the West Antarctic Rift System (WARS), one of the world's largest continental rift zones, over the past 100 million years. An enigmatic feature of the WARS is its transition from a broad rift system during its early history, to a narrow rift more recently. Both broad and narrow rifts are common features on Earth. The proposed research leverages the unique behavior of the WARS to examine the factors that determine how and why these styles of rift behavior develop. Computer models will be developed to match the style of extension in the WARS with the space-time patterns of volcanism and magmatism in the rift. These models will constrain temperatures in the crust and mantle beneath the rift, which are thought to exert strong controls on the style of rift behavior, and will test several hypotheses for the causes of rift-related magmatism. The project contributes to advancing basic science through improved understanding of how continents break apart and how continental rifts and rift sedimentary basins evolve. Improved understanding of these processes provides foundational knowledge that informs assessment of volcano, earthquake, and landslide hazards common in modern rift systems such as the broad cordilleran rift in the western U.S. and the narrow East African Rift. Project outcomes will also provide a process-based geological context for exploration of geothermal energy resources in active rifts and fossil energy resources in sedimentary basins formed by ancient rift systems such as those bounding the eastern U.S. and Gulf of Mexico continental margins. Research conducted during this project will become the basis for development of a hands-on science experiment designed to demonstrate rift behaviors for junior high school and high school science classes. Science kits containing materials for the experiment will be created and added to a K-12 science materials ?lending library? maintained by Colorado State University (CSU). K-12 teachers will be trained to use the science kit during summer teacher workshops that are regularly held on the CSU campus. The research will be conducted with help from one Ph.D. student and one undergraduate student, both of whom will also participate in the K-12 teacher?s workshops and development of the classroom science kit.Technical Project DescriptionThis project will produce new constraints on the thermal evolution of the Earth's mantle beneath the West Antarctic Rift System (WARS) since the onset of extension ca. 105 million years ago. This is critical to understanding WARS extension, as contrasting models have argued for active rifting driven by rising hot mantle plumes, and passive rifting driven by intraplate gravitational forces and far-field boundary forces applied at the edges of the tectonic plate. A suite of finite element models will be developed to examine alternative rifting scenarios in order to determine if models with a hot mantle are consistent with the WARS structural evolution. Multiple simulations will be created to identify warmest and coolest rifting scenarios. These warm and cool end-member temperature fields will be used to test the hypothesis that a plume or plumes are responsible for rifting in the WARS. Various petrogenetic models for rift-related magmatism will be tested by computing the potential magma contribution from each hypothetical source using the P-T fields from the end-member models. The project will produce two self-consistent models of rifting and magmatism in the WARS (warm and cool end members), constrained by the dual requirements of matching the structural evolution of the rift and space-time patterns of magma production and composition.