Alex Burton-Johnson1, Jacqueline Halpin2, Joanne Whittaker2, Felicity Graham2, Sally Watson2
1British Antarctic Survey, Cambridge, United Kingdom, 2Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
We present findings recently published in GRL (Burton-Johnson et al., 2017) on the variability of Antarctic sub-glacial heat flux and the impact from upper crustal geology.
A new method reveals that the upper crust contributes up to 70% of the Antarctic Peninsula’s subglacial heat flux, and that heat flux values are more variable at smaller spatial resolutions than geophysical methods can resolve. Results indicate a higher heat flux on the east and south of the Peninsula (mean 81 mWm-2) where silicic rocks predominate, than on the west and north (mean 67 mWm-2) where volcanic arc and quartzose sediments are dominant. Whilst the data supports the contribution of heat producing element-enriched granitic rocks to high heat flux values, sedimentary rocks can be comparable dependent on their provenance and petrography. Models of subglacial heat flux must utilize a heterogeneous upper crust with variable radioactive heat production if they are to accurately predict basal conditions of the ice sheet. Our new methodology and dataset facilitate improved numerical model simulations of ice sheet dynamics.
The most significant challenge faced remains accurate determination of crustal structure, particularly the depths of the heat producing element-enriched sedimentary basins and the sub-glacial geology away from exposed outcrops. Continuing research (particularly detailed geophysical interpretation) will better constrain these unknowns and the effect of upper crustal geology on the Antarctic ice sheet.