The thermal state of the continental and oceanic lithosphere is reassessed on the basis of new databases for global heat flow and lithospheric heat production, recent advances in thermophysical properties measurements of minerals at high pressures and temperatures, and a better understanding of convective heat loss in young seafloor. The updated global heat flow database incorporates >60,000 records with >44,800 heat flow determinations. The update significantly increases the quantity and spatial coverage of global heat flow data since the last update in 1993. A new family of continental geotherms is proposed that is parametric in surface heat flow and takes advantage of thermophysical property data. The range of geotherms is constrained by xenolith P–T estimates; a cratonic geotherm consistent with a surface heat flow of 40 mW/m2 is particularly well constrained. Upper crustal heat production represents ∼26% of the total surface heat flow. Average heat production for the continental lower crust and mantle are 0.4 μW/m3 and 0.02 μW/m3, respectively. Recent controversy about the interpretation of heat flow observations in young seafloor is resolved by careful filtering of data based on sediment thickness and distance from seamounts and weighting marine studies where the environment of heat flow measurements is carefully documented. Oceanic geotherms, fit to bathymetry and heat flow data, are produced for a plate model with 7 km thick crust, a plate thickness of 95 km, and mantle potential temperature of 1425°C. While the current estimate of global heat loss (44 TW) is reasonable, these new reference models will be instrumental in refining and estimating uncertainty in the solid Earth's global heat loss.
|Advisor:||Chapman, David S.|
|Commitee:||Aster, Richard C., Bartley, John, Nash, Barbara, Wannamaker, Philip E.|
|School:||The University of Utah|
|Department:||Geology and Geophysics|
|School Location:||United States -- Utah|
|Source:||DAI-B 71/07, Dissertation Abstracts International|
|Subjects:||Geophysics, Plate Tectonics|
|Keywords:||Continental lithosphere, Geotherms, Heat flow, Oceanic lithosphere, Radioactivity, Thermal conductivity|
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