Learning From Finland: Variability of Subglacial Heat Flow in Greenland Explored From Geological Units and Radiogenic Heat Production

Abstract

It is well known that geothermal heat flow influences the dynamics of ice sheets. Especially small-scale variations may lead to strong effects, but are not resolvable in most available models. Here, we establish a relationship between large-scale radiogenic heat production (RHP) and geological units for Greenland to assess the local variability of geothermal heat flow (GHF). Our approach combines information on the variability of RHP from samples at coastal regions with geological maps to simulate small-scale variations of RHP under the ice and consequently GHF. We first test our approach for Finland where a unique RHP database is available before applying it to Greenland. RHP is simulated based on two different available geological maps for Greenland leading to different RHP variability. The different geological units with their unique RHP variability have a strong influence on the GHF, leading to significantly different results. For example, in central Greenland, the estimated GHF of the different maps has a difference of more than 20 mW/m². This demonstrates the importance of reliable knowledge of subglacial geology and thermal parameters in order to provide reasonable estimates of the basal conditions of the ice-sheet.