Characterization of Lake Amundsen-Scott, S. Pole: A Ground Geophysical Program

阿蒙森-斯科特湖南极点的表征：地面地球物理计划

• 批准号: 0538097
• 负责人: Sridhar Anandakrishnan
• 金额: $ 23.47万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538097&HistoricalAwards=false
• 关键词: Characterization; Lake; Amundsen; Scott; S.

0538097AnandakrishnanThis award supports a project to intensively study a subglacial Antarctic lake near the geographic South Pole using seismic and radar methods. These ground-based experiments are better suited to determine the presence of water and its thickness than are airborne methods. We hypothesize that there are two end-member explanations for this feature: either the lake is thawed, but freezing on (and likely to have been freezing on through much of the current interglacial period), or it is a frozen, relict lake for which the high basal radar reflectivity is due to intergranular water in a permafrost-like layer beneath the ice. The seismic experiment we propose is ideally suited to examine these alternatives. Intermediate cases of, e.g., a thawed saturated sedimentary base or a smooth crystalline basement layer would also be resolved by this experiment. Seismic reflections are sensitive to changes in acoustic impedance which is strongly variable with fluid content, porosity, and lithology. Water has low density relative to most rocks and low seismic velocity (and nil shear wave velocity) relative to both ice and rock. Thus, discriminating between subglacial water and subglacial rock is a task ideally suited to the seismic reflection technique. This project has significant impacts outside the directly affected fields of Antarctic glaciology and geology. The lake (either thawed or sediments with thin liquid layers around the matrix particles) will have the potential for harboring novel life forms. The experiment has the potential for expanding our information about the newest frontier in life on Earth. The collaboration between PIs in the seismic community and the marine acoustics community will foster cross-disciplinary pollination of ideas, techniques, and tools. In addition to traditional seismic techniques, new methods of data analysis that have been developed by acousticians will be applied to this problem as an independent measure of lake properties. We will train students who will have a wider view of seismology than would be possible in a traditional ocean acoustics or traditional geoscience seismology program of study.

0538097 Anandakrishnan该奖项支持一项利用地震和雷达方法对地理南极附近的冰下南极湖泊进行深入研究的项目。与空中方法相比，这些地面实验更适合于确定水的存在及其厚度。我们假设，对于这一特征有两种最终成员的解释：要么是湖泊解冻，但结冰(很可能在当前间冰期的大部分时间里一直冻结)，要么是一个结冰的残留湖，其高基础雷达反射率是由于冰下类似冻土层的颗粒间水。我们提出的地震实验非常适合于检验这些替代方案。例如，融化的饱和沉积基底或光滑的结晶基底层的中间情况也将通过该实验得到解决。地震反射对声阻抗的变化很敏感，声阻抗随流体含量、孔隙度和岩性而变化很大。相对于大多数岩石，水的密度较低，相对于冰和岩石，水的地震速度(和零横波速度)也很低。因此，区分冰下水和冰下岩石是一项非常适合地震反射技术的任务。该项目对南极冰川学和地质学的直接影响领域之外具有重大影响。湖泊(无论是融化的或基质颗粒周围有薄薄液体层的沉积物)将有可能蕴藏新的生命形式。这项实验有可能扩大我们关于地球上生命最新前沿的信息。地震界和海洋声学界的PI之间的合作将促进思想、技术和工具的跨学科授粉。除了传统的地震技术外，声学家开发的新的数据分析方法将作为湖泊性质的独立衡量标准应用于这一问题。我们将培养学生对地震学有比传统海洋声学或传统地学地震学课程更宽广的视野。