Constraints on the geothermal heat flow of Antarctica and surrounding oceans from new seismic structure models

Douglas A. Wiens1, Weisen Shen1, Andrew Lloyd1, Andrew Nyblade2, Richard Aster3, Terry Wilson4

1Washington University In St Louis, Saint Louis, USA, 2Penn State University, University Park, USA, 3Colorado State University, Fort Collins, USA, 4Ohio State University, Columbus, USA

Geothermal heat flow has a major effect on ice sheet dynamics, but there are few direct measurements of Antarctic heat flow. Previous studies have estimated the geothermal heat flow of Antarctica from seismic structure models, but these efforts have had very limited resolution due to poor seismic station coverage. We have recently constructed two new seismic structure models of Antarctica using complementary methodologies that incorporate data collected from more than 200 temporary broadband seismic stations deployed across Antarctica over the last 15 years. One model seeks to obtain the highest possible resolution within the upper 200 km depth in the well-instrumented region of central and West Antarctica using a joint inversion of Rayleigh wave velocities and receiver functions (Shen et al., submitted). We obtain an estimate of the geothermal heat flux via a Bayesian inversion of Rayleigh wave observations for thermal structure using relationships between seismic velocity and temperature (see Weisen Shen presentation). The second seismic structure model is an adjoint full-waveform inversion for mantle structure beneath the entire continent and surrounding oceans, extending down to mantle transition zone depths (Lloyd et al., in prep). This model allows for lithospheric thickness to be mapped across the entire Antarctic plate, and for corresponding implications for geothermal heat flow to be made. Very thin or absent lithosphere along the Ross Sea Coast from Northern Victoria Land to the Southern Transantarctic Mountains, along the Amundsen coast and continental shelf, and beneath the Antarctic Peninsula suggest the likelihood of higher geothermal heat flow in these locations. Although most of East Antarctica shows thick, cold lithosphere, we also find younger or tectonically modified thinner lithosphere beneath portions of Dronning Maude Land and the Lambert Graben, suggesting the possibility of somewhat higher mantle contributions to heat flux in these areas.

 

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