Geodynamics and Thermal Regime across the Central Transantarctic Mountains from Analysis of Magnetotelluric Measurements

University Of Utah, Salt Lake City UT

Investigators

Abstract

Intellectual Merit: The PIs propose to analyze a transect of 57 high-quality magnetotelluric (MT) soundings acquired over two Antarctic field seasons to examine competing hypotheses for the mechanism of extension and creation of the Transantarctic Mountains. These data will also be used to characterize the thermal regimes of rifted West Antarctica and stable East Antarctica. In the MT method, temporal variations in the Earth's natural electromagnetic field are used as source fields to probe the electrical resistivity structure in the depth range of 1 to 200 km below Earth's surface. Raw MT soundings contain significant information related to the thermal regime beneath the Transantarctic Mountains as it relates to support mechanisms and composition. This information will enable comparison to other rift-platform transitions, such as in the western United States. The distinct character of the MT data will also be correlated with regional aeromagnetic trends and tied to outcrops in terms of distinct lithologies such as meta-sedimentary terranes and plutonic complexes. Specifically, the goals of this research are: to establish the location of the tectonic transition between East and West Antarctica, which may help infer a support mechanism for the Transantarctic Mountains; to use MT data to estimate crustal heat flux into the ice sheet base; and to determine if regional-scale resistivity properties be used as a proxy for lithological discrimination, to support facies extrapolation and terrane reconstruction. Broader impacts: This project involves international collaborations between University of Utah, GNS Sciences Wellington NZ, and Tokyo Institute of Technology Japan. It will support a female post-doc who will gain experience in state of the art geophysical instrumentation, parameters of field survey design, practical logistical matters in remote settings, modern methods of MT inversion, and the relationship between electrical resistivity and physico-chemical state in the Earth. Heat flow estimates could improve models of ice sheet stability.