Global heat flow: A new look

Abstract

A global heat flow map has been derived from existing observations supplemented in areas without data by an empirical predictor based on tectonic setting and age. In continental areas the predictor is based on the observed correlation of heat flow with age of last tectono-thermal event, and in oceanic regions on the observed relation of heat flow to age of ocean floor. The predictor was used to assign mean heat flow values to 5[deg] x 5[deg] grid areas on the globe, weighted according to the relative area of tectonic provinces represented. A spherical harmonic analysis to degree 12 of the heat flow field yields a mean value of 59 mW m-2, a rms residual of 13 mW m-2, and an amplitude spectrum which decreases gradually and almost monotonically from n = 1. The spherical harmonic representation of the heat flow field is free of the unreal distortions which have characterized earlier analyses based on a geographically sparse data set. Areas with residuals greater than 15 mW m-2 comprise less than 19% of the area of the globe, thus indicating that most heat flow provinces have characteristic dimensions adequately represented in a 12-degree analysis.