CAREER: A Comprehensive Seismic Investigation to the Crust and Uppermost Mantle Beneath the South Pole, East Antarctica

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NontechnicalUnderstanding the subsurface structure near the South Pole will answer some of the most exciting scientific questions in Antarctic Earth Science, ranging from the origin of the high subglacial mountains and the southernmost volcanic rocks to the existence of nearby subglacial lakes. However, it has been difficult to answer these questions since the area is remote and the ice cover is thick. Using seismic stations deployed on top of the ice sheet provides an alternative tool to image the continent through the ice, as seismic signals record sensitive information about the geology of the crust below. For example, crustal rocks with more radioactive elements may have caused the ice sheet to melt, creating subglacial lakes, and these rocks can be identified by their unique seismic signatures. This project plans to fill a knowledge gap by deploying new seismic sensors in the South Pole area and collecting data to perform a suite of modern seismic data analyses to produce a variety of seismic observables. These observables will be translated into maps illustrating the physical properties and chemical composition of the underlying crust, and further help determine the thermal properties of the underlying crust near the South Pole. These observations will provide a first-order assessment of the sub-ice geology and insights into the origins of the features such as the Transantarctic Mountains and numerous subglacial lakes. The project will collaborate with K-12 school districts and community colleges in Long Island and provide free geoscience tutoring, public lectures, and inviting K-12 educators to teach students from the field. These efforts will highlight the importance of polar geosciences in a changing climate and elevate the awareness of earth science as a viable career path for high school students. Technical The area within 300 km of the South Pole and its sub-ice structures are equally, if not more, critical in studying Antarctic earth sciences. Given its gateway locality between the high southern Transantarctic Mountains and East Antarctic craton, the area is critical for studying geological history and modern tectonism of the continent, modeling continental dynamics, and developing more accurate ice sheet dynamic models to predict their response to the global climate change. However, these properties have not been systematically studied due to both the remoteness of the continent and its thick ice coverage. In this proposed study, the team will deploy ~ 180 high-frequency 3-component portable seismic nodes and eight broadband sensors near the South Pole, encompassing the nearby southern Transantarctic Mountains and the polar subglacial basins. A combination of linear nodal arrays and 2-dimensional broadband arrays will provide both spatial coverage and the capability to resolve high-resolution subsurface structural variations. Once the data are collected the team will apply a suite of data processing schemes tailored for the array and study area, including 1) a comprehensive surface wave analysis that determines both the isotropic and anisotropic structure of its crust and uppermost mantle; 2) 2-layer receiver function analysis that measures sub-ice layering and Poisson’s ratio; 3) a joint surface wave and receive function inversion that builds seismic models with uncertainties; 4) a novel crustal compositional analysis which uses the seismic attributes to quantify the silica content of the crust, and 5) a joint Monte Carlo thermal inversion that combines Curie-depth measurements with seismologically constrained crustal heat generation to construct a self-consistent, uniform crustal geotherms. This research is complemented by a comprehensive educational component that provides high-quality earth science education to graduate students, as well as to high-need K-12 school districts and community colleges in Long Island.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.