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

这个项目使用计算机模型来研究过去1亿年来控制西南极裂谷系统(WARS)形成的过程，西南极裂谷系统是世界上最大的大陆裂谷带之一。这场战争的一个神秘特征是，它从早期历史上的宽阔裂痕系统过渡到了最近的狭窄裂痕系统。宽裂缝和窄裂缝都是地球上常见的特征。这项拟议的研究利用战争的独特行为来检查决定这些类型的裂痕行为如何发展以及为什么发展的因素。将开发计算机模型，以将战争中的扩张风格与裂谷中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方地壳和地幔的温度，这些温度被认为对裂谷行为的方式施加了强有力的控制，并将检验与裂谷相关的岩浆活动原因的几个假说。该项目通过改善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了解，促进了基础科学的发展。对这些过程的更深入了解为评估火山、地震和山体滑坡提供了基础知识，这些危险在现代裂谷系统中很常见，例如美国西部的宽阔的科迪勒裂谷和狭窄的东非裂谷。项目成果还将为勘探活动裂谷中的地热能资源和古裂谷系统形成的沉积盆地中的化石能源提供基于过程的地质背景，例如那些与美国东部和墨西哥湾大陆边缘接壤的沉积盆地。在这个项目中进行的研究将成为开发实践科学实验的基础，该实验旨在展示初中和高中科学课堂上的裂痕行为。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？借阅图书馆？由科罗拉多州立大学(CSU)维护。在CSU校园定期举办的暑期教师讲习班上，K-12教师将接受使用科学工具包的培训。这项研究将在一名博士生和一名本科生的帮助下进行，他们两人都将参加K-12教师S的研讨会和课堂科学工具包的开发。技术项目描述该项目将对西南极裂谷系统(WARS)自1.05亿年前开始伸展以来的地幔热演化产生新的限制。这对于理解战争的延伸至关重要，因为不同的模型认为，由上升的地幔热柱驱动的主动裂谷，以及由施加在构造板块边缘的板内重力和远场边界力驱动的被动裂谷。将开发一套有限元模型来研究不同的裂谷情景，以确定具有热地幔的模型是否与战争的结构演化一致。将创建多个模拟来确定最热和最冷的裂谷情景。这些温暖和凉爽的终端成员的温度场将被用来检验这样的假设，即一个或多个羽流应为战争中的裂痕负责。各种与裂谷有关的岩浆活动的岩石成因模型将通过使用终端成员模型中的P-T场来计算每个假设来源的潜在岩浆贡献来检验。该项目将产生战争中裂谷作用和岩浆作用的两种自洽模式(温端成员和冷端成员)，受裂谷结构演化和岩浆生产和组成的时空模式相匹配的双重要求的制约。

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.