A COMPARATIVE-STUDY OF PARAMETERIZED AND FULL THERMAL-CONVECTION MODELS IN THE INTERPRETATION OF HEAT-FLOW FROM CRATONS AND MOBILE BELTS

Heat flow from Archean cratons worldwide is typically lower than from younger mobile belts surrounding them. The contrast in heat flow betwe en cratons and mobile belts has been attributed in previous studies to the greater thermal resistance of thicker lithosphere beneath the cra tons which impedes the flow of mantle heat through the cratons and for ces more mantle heat to escape through thinner mobile belt lithosphere . This interpretation is based on thermal models which employ a parame terized convection algorithm to calculate heat transfer in the sublith ospheric mantle. We test this interpretation by comparing thermal mode ls constructed using the parameterized convection scheme with models d eveloped using an algorithm for full thermal convection. We show that thermal models constructed using the two different convection algorith ms yield similar surface heat flow and thermal structure to moderate d epths within the lithosphere. Therefore, we conclude that the interpre tation of the heat-flow observations in terms of thicker lithosphere u nder Archean cratons than under mobile belts is robust in the sense th at surface heat flow is not sensitive to the details of heat transfer within the convecting mantle and how deep mantle heat is delivered to the base of the lithosphere.