Refinements and Interpretation of Images of the Antarctic Crust and Upper Mantle

该奖项由极地方案办公室南极地质和地球物理方案提供，为南极洲的地震研究提供资金。南极洲下面的地壳和上地幔仍然是直接位于地球表面之下的最不为人所知的区域。地震面波频散特别适合于提供关于南极洲地壳和上地幔的信息，因为面波层析成像在接收站相对较少和地震活动较远的地区效果良好。这项研究有三个主要目标：继续改进南极洲和周围海洋之下地壳和上地幔的地震图像，改进量化这些图像质量的方法，以及开始阐明上地幔中一些较突出的地震速度异常的性质和原因。先前的工作致力于发展和应用估计和评估南部高纬度地震模型的能力。这项研究将继续推进这些能力，但更大一部分的努力将致力于了解南极板块下的地壳和上地幔的结果图像。工作将分为以下五个主题领域：（1）连续的面波频散测量和数据处理，（2）面波层析成像、分辨率分析和反演的方法改进，（3）确定方位各向异性是否可以稳健估计的实验，（4）估计南半球高纬度地壳和上地幔的精细模型，（5）发展和应用解释新模型的方法，以获得对南极软流圈、岩石圈和地壳的温度、组成和演化的地球物理见解。来自全球网络和南极洲及其周围地区临时阵列的地震数据集迅速增加，有望将联合收割机与表面波层析成像和反演的改进结合起来，大大改善南极板块下地壳和上地幔地震结构的图像。这些改进将有助于为更好地了解南极岩石圈地球物理学提供基础。特别值得进一步阐明的结构和构造特征包括：西南极裂谷系与新生代东、西南极洲分离的关系，东南极克拉通与世界其他克拉通的关系，东南印度洋脊与澳-南不整合面附近的最上地幔，南极板块下上地幔的热结构和成分结构，以及南极洲和南大洋的各向异性（径向和方位）分布。这一研究将有助于我们更广泛地了解南极地壳和上地幔。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, provides funds for a seismological study of Antarctica. The crust and upper mantle beneath Antarctica remain among the most poorly understood regions directly underlying Earth's surface. Seismic surface wave dispersion is uniquely suited to providing information about the crust and upper mantle beneath Antarctica because surface wave tomography can perform well in regions with relatively few receiving stations and remote seismicity. There are three principal goals for this research: to continue to refine the seismic images of the crust and upper mantle beneath Antarctica and surrounding oceans, to improve methods to quantify the quality of these images, and to begin to elucidate the nature and cause of some of the more prominent seismic velocity anomalies in the uppermost mantle. Prior work was devoted to developing and applying the capabilities to estimate and assess seismic models at high southern latitudes. This research will continue to advance these capabilities, but a larger fraction of the efforts will be devoted to understanding the resulting images of the crust and upper mantle underlying the Antarctic Plate. The work will be divided into the following five subject areas: (1) continued surface wave dispersion measurements and data processing, (2) methodological improvements in surface wave tomography, resolution analysis, and inversion, (3) experiments to determine whether azimuthal anisotropy can be estimated robustly, (4) estimation of a refined model of the crust and upper mantle at high southern latitudes, and (5) development and application of methods to interpret the new model to gain geophysical insight into the temperature, composition, and evolution of the Antarctic asthenosphere, lithosphere, and crust. The rapidly growing seismic data sets from both global networks and temporary arrays in and around Antarctica promise to combine with improvements in surface wave tomography and inversion to significantly refine the images of the seismic structure of the crust and upper mantle beneath the Antarctic Plate. These refinements will help to provide the basis for an improved understanding of the geophysics of the Antarctic lithosphere. Structural and tectonic features that are of particular interest for further elucidation include: the West Antarctic Rift system with implications concerning the separation between East and West Antarctica during the Cenozoic, the East Antarctic craton in relation to other cratons in the world, the SE Indian Ridge with emphasis on the uppermost mantle near the Australian-Antarctic Discordance, the thermal and compositional structure of the upper mantle beneath the Antarctic Plate, and the distribution of anisotropy (radial and azimuthal) across Antarctica and the southern oceans. This research should help to advance broadly our understanding of the Antarctic crust and upper mantle.