Geothermal gradient model (2023) created by Geognostics with support from government and industry. The geothermal gradient describes how temperature increases with depth inside the Earth.

It is expressed in degrees Celsius per kilometre (°C/km). The linear geothermal gradients are from the top of SEEBASE to the surface. These were calculated using the combined heat-flow contribution of multiple crustal heat sources including upper mantle, radiogenic upper crust, and sediment thickness. The highest calculated geothermal gradients are generally related to areas interpreted to be underlain by granitic intrusions in the basement. The composition and heat production characteristics of the granites are largely unconstrained by analyses