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

该项目使用计算机模型来研究在过去1亿年中控制南极西部裂谷系统（WARS）形成的过程，这是世界上最大的大陆裂谷带之一。战争的一个神秘特征是它从早期的一个宽裂谷系统转变为最近的一个窄裂谷系统。宽裂缝和窄裂缝是地球上的共同特征。该研究利用了战争的独特行为来研究决定这些类型的裂谷行为如何以及为什么发展的因素。将建立计算机模型，使WARS的伸展样式与裂谷中的火山活动和岩浆活动的时空模式相匹配。这些模型将限制裂谷下地壳和地幔的温度，这些温度被认为对裂谷行为的类型施加了强有力的控制，并将测试几个关于裂谷相关岩浆活动原因的假设。该项目通过提高对大陆如何分裂以及大陆裂谷和裂谷沉积盆地如何演化的理解，有助于推进基础科学。对这些过程的进一步了解为评估现代裂谷系统（如美国西部宽阔的科迪勒兰裂谷和狭窄的东非裂谷）中常见的火山、地震和滑坡灾害提供了基础知识。项目成果还将为勘探活动裂谷中的地热资源和古裂谷系统（如美国东部和墨西哥湾大陆边缘的裂谷系统）形成的沉积盆地中的化石能源资源提供基于过程的地质背景。在此项目中进行的研究将成为开发动手科学实验的基础，旨在为初中和高中科学课展示裂缝行为。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？图书馆吗?由科罗拉多州立大学（CSU）维护。在科罗拉多州立大学校园定期举行的夏季教师研讨会上，K-12教师将接受使用科学工具包的培训。该研究将在一名博士生和一名本科生的帮助下进行，这两名学生也将参与K-12教师？S工作坊及发展课堂科学教材。本项目将对南极西部裂谷系（WARS）自1.05亿年前伸展开始以来的地幔热演化产生新的约束。这对于理解WARS伸展是至关重要的，因为对比模型认为，由上升的热地幔柱驱动的主动裂谷，以及由板块内引力和构造板块边缘施加的远场边界力驱动的被动裂谷。将开发一套有限元模型来检验不同的裂谷情景，以确定具有热地幔的模型是否与WARS结构演化相一致。将创建多个模拟来确定最热和最冷的裂谷情景。这些温暖和寒冷的端元温度场将被用来测试羽流或羽流是造成战争裂谷的假设。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，将测试与裂谷有关的岩浆作用的各种岩石成因模型。在满足裂谷构造演化和岩浆产生和组成时空格局的双重要求下，本项目将建立两个自一致的裂谷和岩浆作用模型（暖端和冷端）。

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.