Thermal and Fluid State of the Lithosphere Beneath South Pole Region, East Antarctica, from Magnetotelluric Measurements

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OPP 9615254 Wannamaker Abstract The award supports a project to extend knowledge of the thermal and physico-chemical state (fluids, melts) of the deep crust and upper mantle of Antarctica with magnetotelluric (MT) profiling of the South Pole area. In the MT method, temporal variations in the Earth's natural electromagnetic (EM) field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 100 kilometers (km), or more. Geophysical methods such as MT are appropriate in Antarctica because of the predominance of thick ice cover (95% of the surface) and the difficult operating environment. The effort will consist of about 16 sites over a length of 90 km, offset from South Pole station about 5 km and oriented grid NE-SW, normal to the Transantarctic Mountains (TAM). The main purposes are three- fold. First, the method will test the cratonic character of the lithosphere of this part of East Antarctica to depths of 100-150 km and will allow comparison of its resistivity structure with that imaged in extensional central West Antarctica (CWA) by the same research group. Second, this experiment will be conducted over the very thick and cold ice sheet extant at South Pole, conditions that are very different those at CWA, so that this project should make MT surveying more feasible over the entire continent. Third, the results will provide the crustal response baseline for possible long-term MT monitoring to lower mantle depths at South Pole. This experiment should lead to important advances in understanding of the crustal and mantle structure of the central part of the Antarctic continent.