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

智力价值：这项研究将把维多利亚陆地盆地南部的沉降史置于定量的地球动力学背景下，并将评估与新近纪晚期火山加载相关的挠曲对Erebus火山群对地壳的影响。为此，将扩展西南极裂谷系统的伸展地球动力学模型，以包括假设发生在古近纪晚期和中新世的伸展间歇，并开发一个新的火山加载和相关岩石圈挠曲的地球动力学模型。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，以检验拟议的伸展间歇期对伸展样式的影响，重点是发展一种基于过程的理解，即从晚白垩世弥漫的裂谷样式转变为新生代更集中的裂谷样式。这些模型将检验伸展间歇导致裂谷风格改变的假设，并将对间歇的时间和持续时间施加限制。该项目的第二阶段将使用先前模型的热学和流变学性质来约束岩石圈的弯曲刚性，以模拟对火山载荷的弯曲响应，以测试以下假设：挠曲下沉导致ANDRILL和-1A站点的地面和浮冰之间的循环变化，使从该岩心对气候记录的解释复杂化，以及挠曲有助于AND-2B站点的应力方向，这与预期的区域伸展应力方向不一致。广泛的影响：该项目将培训一名本科生和一名理工科学生。外展活动包括在地区性高中、专科学校和有地质学课程的四年制大学进行一系列有计划的讲座。

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.