HYDROLOGICAL DISTURBANCES OF THE CONDUCTIVE HEAT-FLOW IN THE UPPER CRUST - PROBLEMS OF CORRECTING MEASURED HEAT-FLOW DATA

The upper crustal-scale convection of fluids is one of the main factor s distorting the conductive geothermal field. Geothermal anomalies cau sed by water circulation, as a rule, exceed the contributions from oth er factors (relief, sedimentation, structural and climatic effects). T he measured temperature gradient has to be corrected before being used for calculation of the heat flow. In the present work, certain 2-D hy drothermal convection models have been analyzed using various permeabi lity distributions and spatial configurations of fluid systems. Permea bility anisotropy has also been included in some of the models, and va riations of this parameter in the range 10(-10)-10(-16) m(2) have been considered. Numerical simulations reveal the possibility of considera ble advective disturbances to the heal Bow. These disturbances depend on the physical parameters, and strongly on the geometry of fluid circ ulation. The magnitude of the hydrologic correction has been assessed for a variety of geological environments.