Temperatures in the Crust and Lithosphere

Heat flow measurements place important constraints on the temperature profile of the crust and lithosphere. Pollack et al. [1993] reported a global synthesis of 24,744 heat flow measurements that constrain the global heat loss to be 44.2 x 10 W/yr, some 4-8% higher than earlier estimates. The global heat flow pattern correlates well with seismic tomographic maps [ Zhang and Tanimoto, 1993] at shallow depths, implying that seismic shear velocity variations at these depths are strongly correlated with temperature. Stein and Stein [1992] used improved oceanic heat flow data to construct a new model for oceanic lithosphere that is both hotter (1400C at its base) and thinner (95 km) than previous models. New oceanic lithospheric temperature profiles have also been constructed that are consistent with heat flow and bathymetry constraints and incorporate temperature-dependent mineral properties [ Denlinger, [1992]. General steady-state geotherms for the continental crust that satisfy heat flow data and use thermal parameters appropriate for crustal compositions have been developed as well [ Chapman and Furlong, 1992].