Constrainting Subglacial Heat Flux in Antarctica from Thermal Conductivity and Subglacial Lakes

• Main Author: Willcocks, Simon Robert
• Other Authors: Hasterok, Derrick, Hand, Martin, School of Geology and Earth Science
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: Antarctica; Geothermics; Thermal Conductivity; Geothermal Heat Flux; Thermal Refraction; Subglacial Topography; Subglacial Lakes; Antarctic; Paterson; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://hdl.handle.net/2440/137900

Developing accurate models for the dynamics of ice sheets requires detailed knowledge of the temperature field within. An important constraint on internal ice sheet temperature is provided by geothermal heat flux, the heat flow from the solid Earth to the base of the ice sheet (Fowler 2006). This flow of heat is not uniform, varying as a result of differences in thermal properties (i.e., thermal conductivity and heat production) and variations in heat transfer across the lithosphere asthenosphere boundary. Since temperature can affect a range of ice properties, from strain rate to hardness and melting rate (Paterson 1994), it is important that we have a detailed understanding of the heat flux both below and within the Antarctic Ice Sheet so that I can accurately map internal temperature. In this thesis, I examine the heat flux in Antarctic environments as well as the properties and factors that distort it. I also take an indirect approach to test geothermal heat flux models by using melting associated with subglacial lakes as a constraint. Heat can move both vertically and horizontally in order to find the path of least thermal resistance to the surface. The path is dictated by the thermal conductivity of the crustal material as heat will attempt to move through the most conductive material. In a subglacial valley, or buried bedrock high, most heat will move through the more conductive bedrock, resulting in heat being moved away from subglacial valleys and into bedrock in regions of geological contacts whereby heat will move into the more conductive of the two mediums. The result is the creation of localized regions where heat flux at the base of the ice sheet can be 80 to 120% of the regional heat flux creating localized regions of elevated/reduced temperature. Having demonstrated the underlying bedrock thermal geology is critical to mapping the flow of heat through the Antarctic ice sheet, I collected the thermal conductivity on 49 Antarctic rock samples and combined them with a larger global database to ...