Anisotropic Ice and Stratigraphic Disturbances

各向异性冰和地层扰动

• 批准号: 1246045
• 负责人: Edwin Waddington
• 金额: $ 24万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1246045&HistoricalAwards=false
• 关键词: Anisotropic; Ice; Stratigraphic; Disturbances

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.

Waddington/1246045 该奖项支持一个研究极地冰盖地层中褶皱和其他扰动的发生和增长的项目。这项工作的智力价值在于，它将导致人们更好地理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哪些过程可以引发此类扰动等问题。 极地冰原上的雪通常是平坦的，厚度沿各层缓慢变化。 然而，冰芯和透冰雷达表明，在某些情况下，在转化为冰并经过长时间掩埋后，冰层可能会折叠，形成捏胀结构（boudinage），并被冰流剪切，在尺度从厘米到数百米不等。造成这些干扰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而级联到更大的尺度。导致厘米级层变形的晶体尺度过程将使用微观结构建模软件包 Elle 进行建模，并受到来自西南极冰盖冰芯的织物薄片和颗粒伸长测量的约束。全应力连续各向异性冰流模型与冰结构演化模型相结合，将用于研究各向异性冰的整体流动，以了解米级和更大尺度上流动扰动的演化和增长。这项研究的结果将有助于未来的冰芯选址、冰芯和雷达地层学的解释，并将为冰盖流动模型提供流变学和地层学的改进描述。更广泛的影响是它将带来更多的了解负责地层扰动的冰动力学。这些信息对于限制冰芯的深度-年龄关系以进行古气候研究很有价值。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方面未来重要问题所需的人才。该研究将通过外展活动向公众传达，研究结果将通过公众和专业会议以及期刊出版物传播。该项目不需要在南极洲进行实地工作。