Anisotropic Ice and Stratigraphic Disturbances

Waddington/1246045该奖项支持一个项目，以调查在极地冰盖的地层中看到的褶皱和其他干扰的发生和增长。这项工作的智力价值在于，它将导致更好地了解控制冰中这些地层特征发展的颗粒尺度过程，并将有助于回答诸如什么过程可以引发这种扰动等问题。 雪沉积在极地冰盖上，通常是平坦的，厚度沿着层缓慢变化。 然而，冰芯和冰穿透雷达表明，在某些情况下，在转化为冰之后，经过长时间的埋藏，这些层可以折叠，发展出捏涨结构（石香肠），并被冰流剪切，规模从厘米到数百米不等。造成这些扰动的过程仍然知之甚少。扰动似乎首先在冰晶尺度上发展，然后随着持续的冰流和应变级联到更大的尺度。晶体尺度的过程造成厘米级层的扭曲将使用Elle，微观结构建模包，并约束从西南极冰盖划分冰芯的织物薄片和晶粒伸长测量。一个全应力连续各向异性冰流模型耦合到冰结构演变模型将被用来研究各向异性冰的整体流动，了解流量扰动的米和更大规模的演变和增长。这项研究的结果将有助于未来的冰芯选址，并解释冰芯和雷达的地层，并将提供更好的流变学和地层学的描述冰盖流动models.The更广泛的影响是，它将带来更多的理解冰动力学地层扰动负责。这些信息对冰芯深度-年龄关系的研究具有重要的参考价值。这将使研究人员能够更准确地了解当前的气候变化。该项目将为研究生提供三年的支持，并为本科生研究助理提供支持和研究经验;这将有助于培养解决冰川学和气候变化未来重要问题所需的人才。将通过外联活动向公众宣传研究结果，并通过公共和专业会议以及期刊出版物传播研究结果。该项目不需要在南极洲进行实地工作。

Waddington/1246045 This award supports a project to investigate the onset and growth of folds and other disturbances seen in the stratigraphic layers of polar ice sheets. The intellectual merit of the work is that it will lead to a better understanding of the grain-scale processes that control the development of these stratigraphic features in the ice and will help answer questions such as what processes can initiate such disturbances. Snow is deposited on polar ice sheets in layers that are generally flat, with thicknesses that vary slowly along the layers. However, ice cores and ice-penetrating radar show that in some cases, after conversion to ice, and following lengthy burial, the layers can become folded, develop pinch-and-swell structures (boudinage), and be sheared by ice flow, at scales ranging from centimeters to hundreds of meters. The processes causing these disturbances are still poorly understood. Disturbances appear to develop first at the ice-crystal scale, then cascade up to larger scales with continuing ice flow and strain. Crystal-scale processes causing distortions of cm-scale layers will be modeled using Elle, a microstructure-modeling package, and constrained by fabric thin-sections and grain-elongation measurements from the West Antarctic Ice Sheet divide ice-core. A full-stress continuum anisotropic ice-flow model coupled to an ice-fabric evolution model will be used to study bulk flow of anisotropic ice, to understand evolution and growth of flow disturbances on the meter and larger scale. Results from this study will assist in future ice-core site selection, and interpretation of stratigraphy in ice cores and radar, and will provide improved descriptions of rheology and stratigraphy for ice-sheet flow models.The broader impacts are that it will bring greater understanding to ice dynamics responsible for stratigraphic disturbance. This information is valuable to constrain depth-age relationships in ice cores for paleoclimate study. This will allow researchers to put current climate change in a more accurate context. This project will provide three years of support for a graduate student as well as support and research experience for an undergraduate research assistant; this will contribute to development of talent needed to address important future questions in glaciology and climate change. The research will be communicated to the public through outreach events and results from the study will be disseminated through public and professional meetings as well as journal publications. The project does not require field work in Antarctica.