Three-dimensional modelling of deep temperature and heat flow anomalies with applications to geothermics of the Pannonian basin

Abstract

Abstract On the basis of the solution of the three-dimensional, stationary equation of heat conduction with variable thermal conductivity and heat generation, a geothermal model of the crust and upper mantle beneath the Pannonian basin is constructed. Present calculations indicate that the heat flow in the area investigated has an average positive anomaly of 40 mW/m 2 . The average temperature anomaly on the Moho-surface is 500 K, increasing with depth. The melting temperature is reached at depths of 70–80 km (in some particular areas at 65 km). The upper boundaries of the high-conductivity layer and the low-velocity zone in the Pannonian basin are also about the same depths as indicated above, and contours of the melted region coincide well with the zone of the Miocene andesite-rhyolite volcanism. The thermal state of the crust, likewise its structural composition, is rather uniform. In the upper mantle, however, significant local temperature inhomogeneities exist. Additional, non-radiogenic heating is of primary importance in the formation of temperature anomalies of the Pannonian basin. It results from part of the crust and upper mantle having been heated in the past up to melting, or to temperatures close to melting, which is now cooling. The nature of this extra heat source is not yet clear. The results of this study suggest that the terrestrial heat flow measured in the Pannonian basin might have been overestimated.