Geodynamic Models of Subsidence and Lithospheric Flexure at the ANDRILL Drill Sites: Implications for Cenozoic Tectonics and Ice Sheet History

智力优势：这项研究将把南部维多利亚陆地盆地的沉降历史纳入定量地球动力学背景，并将评估与Erebus火山群对地壳的晚第三纪火山负荷相关的挠曲影响。这将通过扩展西南极裂谷系伸展的地球动力学模型来实现，以包括假设在晚古近纪和中新世期间发生的伸展间断，并通过开发火山负荷和相关岩石圈挠曲的新地球动力学模型来实现。将使用有限元和有限差分建模方法。在该项目的第一阶段，将开发一系列伸展地球动力学模型，以研究拟议的伸展间断对伸展样式的影响，重点是开发一个基于过程的理解，了解裂谷样式从晚白垩世的扩散到新生代的集中。这些模型将检验伸展间断导致裂谷样式变化的假设，并将对间断的时间和持续时间进行限制。该项目的第二阶段将使用先前模型的热和流变特性来约束岩石圈的抗弯刚度，以便模拟对火山载荷的弯曲响应，以测试弯曲沉降导致ANDRILL AND-1A站点的接地冰和浮冰之间的周期性变化的假设，使对该核心的气候记录的解释复杂化，弯曲对AND-2B场地的应力方向有贡献，这与预期的区域伸展应力方向不一致。更广泛的影响：该项目将培训一名本科生和一名硕士。学生.外联活动包括在地区高中、大专和有地质学课程的4年制大学举办一系列计划中的讲座。

Intellectual Merit: This research will place the subsidence history of the southern Victoria Land Basin into a quantitative geodynamic context and will assess the influence of flexure associated with late Neogene volcanic loading of the crust by the Erebus Volcanic Group. This will be done by extending geodynamic models of extension in the West Antarctic Rift System to include extensional hiatuses hypothesized to have occurred during the Late Paleogene and Miocene, and by developing a new geodynamic model of volcanic loading and associated lithosphere flexure. Finite element and finite difference modeling methods will be used. In the first phase of the project, a series of extensional geodynamic models will be developed to examine the effect that proposed extensional hiatuses have on the style of extension, with emphasis placed on developing a process based understanding of the change in rift style from diffuse during the Late Cretaceous to more focused during the Cenozoic. The models will test the hypotheses that extensional hiatuses led to the change in rifting style, and will place constraints on the timing and duration of the hiatuses. The second phase of the project will use the thermal and rheological properties of the previous models to constrain the flexural rigidity of the lithosphere in order to model the flexural response to volcanic loading to test the hypotheses that flexural subsidence contributed to cyclic changes between grounded and floating ice at the ANDRILL AND-1A site, complicating interpretations of the climatic record from this core, and that flexure contributes to the stress orientation at the AND-2B site, which is inconsistent with the expected regional extensional stress orientation.Broader impacts: The project will train an undergraduate student and an M.S. student. Outreach activities include a planned series of talks at regional high schools, junior colleges, and 4-year colleges that have geology programs.