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

该奖项支持一项利用地震和雷达方法深入研究地理南极附近冰下南极湖泊的项目。这些基于地面的实验比机载方法更适合于确定水的存在及其厚度。我们假设对这一特征有两种端元解释：要么该湖泊已经解冻，但仍在冻结（并且很可能在当前间冰期的大部分时间里一直在冻结），要么它是一个冻结的、残缺的湖泊，其高基础雷达反射率是由于冰下永久冻土层中的粒间水造成的。我们提出的地震实验是检验这些备选方案的理想选择。中间的情况，例如，融化的饱和沉积基底或光滑的结晶基底层也可以通过这个实验来解决。地震反射对声阻抗的变化很敏感，而声阻抗随流体含量、孔隙度和岩性变化很大。相对于大多数岩石，水的密度低，相对于冰和岩石，水的地震速度低（无横波速度）。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。该项目在南极冰川学和地质学直接影响领域之外具有重大影响。这个湖（要么是解冻的，要么是基质颗粒周围有薄薄的液体层的沉积物）将有可能庇护新的生命形式。这个实验有可能扩大我们对地球上生命最新领域的了解。地震学界和海洋声学学界的pi之间的合作将促进跨学科的思想、技术和工具的交流。除了传统的地震技术外，声学学家开发的新的数据分析方法将作为湖泊性质的独立测量方法应用于该问题。我们将培养学生拥有比传统海洋声学或传统地球科学地震学专业更广阔的地震学视野。

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.