Paper No. 6-4
Presentation Time: 9:05 AM
EFFECTS OF VARIABLE GEOTHERMAL HEAT FLUX ON GLACIATED LANDSCAPES
A variety of influences, from volcanic to tectonic and erosional to depositional, have sculpted modern geomorphology. In particular, glaciers and associated processes have had major influences on the form of many regions throughout the world. In tectonically active, mountainous topography, the combination of erosional and tectonic influences can lead to distinct large-scale characteristics, such as those described by assumptions like the glacial buzzsaw. However, glacier development and subsequent landscape evolution are affected by many factors beyond just uplift, such as geothermal heat flux. Geothermal heat flux varies widely across the earth due to differences in crustal thickness, lithology and volcanism. For example, an area like Iceland with active rifting and volcanic activity will have significantly higher than average heat flux. Past studies have been done to assess the influence of geothermal heat flux on specific glaciers, but there is a lack of study on the impact of geothermal heat flux on general glacier development as well as its affect on glacial landscape evolution. This study uses the ICE-Cascade landscape evolution model to determine the impact of geothermal heat flux on glacier area, thickness and erosion rates. Multiple runs were done using identical initial conditions and only modifying the heat flux values. Each run produced three glaciations of varying area and thickness over a 250 kyr time period. From the runs done with uniform heat flux, it can be seen that glacier area and thickness decreases with an increase in geothermal heat flux. Heat flux was increased from the continental crust average (68 mW/m2) to the Iceland average (175 mW/m2) (Davies and Davies, 2010; Hjartarson, 2015). Due to this increase, there was an 11.1% decrease in mean thickness and a 21.1% decrease in mean area over the 250 kyr runs. Erosion rates were also affected by the change in geothermal heat flux. The maximum average glacial erosion rate increased 24.0% in the high heat flux run. It is expected that similar results will be seen with the spatially variable heat flux runs, although the impact will likely be more localized. Overall, this study indicates that geothermal heat flux can have a significant impact on the formation and evolution of glaciated landscapes, especially over long time scales.