A New Approach to Investigate the Seismic Velocity Structure beneath Antarctica

Abstract: Intellectual Merit: Numerous candidate models for the geologic processes that have shaped the Antarctic continent have been proposed. To discriminate between them, detailed images of the upper mantle structure are required; however, the only existing continental-scale images of seismic structure beneath Antarctica lack sufficient resolution to delineate important, diagnostic features. Using newly available data from various Antarctic seismic networks, the PI will employ the adaptively parameterized tomography method to develop a high-resolution, continental-scale seismic velocity model for all of Antarctica. The proposed tomography method combines regional seismic travel-time datasets in the context of a global model to create a composite continental-scale model of upper mantle structure. The proposed method allows for imaging of finer structure in areas with better seismic ray coverage while simultaneously limiting the resolution of features in regions with less coverage. This research will help advance understanding of important global processes, such as craton formation, mountain building, continental rifting and associated magmatism. Additionally, the proposed research will have important impacts on other fields of Antarctic science. Constraints provided by tomographic results can be used to develop thermal models of the lithosphere needed to characterize the history and dynamics of ice sheets. Also, further constraints on lithospheric structure are required by climate-ice models, which are focused on understanding the cooling history of the Antarctic continent.

Broader impacts: The PI is a new faculty member at the University of Alabama after having been funded as a National Science Foundation Postdoctoral Fellow in Polar Regions Research. The graduate student supported by this project is new to polar research. Through the UA-Tuscaloosa Magnet School partnership program, the PI will educate K-12 students about the Antarctic environment and associated career opportunities through various online and hands-on activities. University of Alabama dedicates a significant percentage of its enrollment space to underrepresented groups.

摘要：
学术价值：针对塑造南极大陆的各类地质过程，学界已提出诸多候选模型。要对这些模型进行甄别，需要获取上地幔结构的精细成像数据；然而目前已有的南极大陆尺度下的地震结构成像资料，分辨率不足，无法勾勒出关键的诊断性构造特征。本项目负责人（Principal Investigator，PI）将利用各类南极地震台网的最新公开数据，采用自适应参数化层析成像方法，构建覆盖全南极的高分辨率大陆尺度地震速度模型。所提出的层析成像方法将区域地震走时数据集与全球模型框架相结合，可生成上地幔结构的综合大陆尺度模型。该方法能够在地震射线覆盖度较高的区域实现更精细的结构成像，同时对覆盖度较低区域的构造分辨率进行合理限制。本研究将有助于加深学界对克拉通形成、造山作用、大陆裂谷作用及相关岩浆作用等重要全球地质过程的认知。此外，本研究还将对南极科学的其他领域产生重要影响：层析成像结果提供的约束条件，可用于构建岩石圈热模型，以表征冰盖的演化历史与动力学特征；聚焦于南极大陆冷却历史研究的气候-冰盖模型，也需要更多针对岩石圈结构的约束条件。

推广影响力：本项目负责人此前以美国国家科学基金会极地研究博士后研究员身份获得资助，现为阿拉巴马大学的新任教职人员。本项目资助的研究生此前尚未涉足极地研究领域。通过与阿拉巴马大学塔斯卡卢萨磁石学校的合作项目，本项目负责人将通过各类线上及实操活动，向K12阶段学生科普南极环境相关知识，并介绍相关职业发展机会。阿拉巴马大学将其大量招生名额分配给代表性不足的群体。