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

使用地球动力学模型约束西南极裂谷的裂谷和岩浆作用

基本信息

批准号：
1644251
负责人：
Dennis Harry
金额：
$ 31.58万
依托单位：
Colorado State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-04-01 至 2022-03-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1644251&HistoricalAwards=false
关键词：
Constraining Rifting Magmatism West Antarctic

项目摘要

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.

非技术项目描述该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，该裂谷系统是世界上最大的大陆裂谷区之一。战争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系统。宽裂缝和窄裂缝都是地球上的常见特征。拟议的研究利用战争的独特行为来研究决定这些裂痕行为如何以及为何发展的因素。将开发计算机模型，以将战争中的延伸方式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，这被认为对裂谷行为的类型有强有力的控制，并将测试与裂谷相关的岩浆作用的原因的几种假设。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可以为评估现代裂谷系统（例如美国西部广阔的科迪勒拉裂谷和狭窄的东非裂谷）中常见的火山、地震和山体滑坡灾害提供基础知识。项目成果还将为勘探活动裂谷中的地热能源和由古代裂谷系统（例如美国东部和墨西哥湾大陆边缘的边界系统）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。该项目期间进行的研究将成为开发动手科学实验的基础，该实验旨在展示初中和高中科学课程的裂痕行为。将创建包含实验材料的科学套件并将其添加到 K-12 科学材料“借阅库”中。由科罗拉多州立大学 (CSU) 维护。 K-12 教师将在科罗拉多州立大学校园定期举办的夏季教师研讨会上接受使用科学套件的培训。该研究将在一位博士的帮助下进行。一名学生和一名本科生，两人也将参加 K-12 教师讲习班和课堂科学套件的开发。技术项目描述该项目将对西南极裂谷系统 (WARS) 下地幔的热演化产生新的约束，该热演化自大约开始延伸以来。 1.05亿年前。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羽流驱动的，被动裂谷是由板内重力和施加在构造板块边缘的远场边界力驱动的。将开发一套有限元模型来检查替代裂谷情景，以确定热地幔模型是否与 WARS 结构演化一致。将创建多个模拟来识别最温暖和最冷的裂谷场景。这些温暖和凉爽的端元温度场将用于检验一个或多个羽流导致 WARS 中裂谷的假设。将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来测试与裂谷相关的岩浆作用的各种岩石成因模型。该项目将在 WARS 中产生两个自洽的裂谷和岩浆作用模型（热端元和冷端元），受到匹配裂谷结构演化和岩浆产生和成分时空模式的双重要求的约束。