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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS017 Poster presentation 2389
Heat and groundwater flow modeling in the lithosphere of the Eastern
Carpathians Bend
Dr. Venera Dobrica
Natural Fields Institute of Geodynamics, Bucharest, Romania IASPEI
Helmut Wilhelm
The geothermal regime in the Earths lithosphere is given mainly by the transport to the surface of heat
from the mantle and of heat that is generated by the decay of radioactive isotopes in the rocks. The
main mechanisms of heat transfer are conduction and convection by moving fluids. The circulating fluids
can have an important effect on the heat transport in sediments during basin development, producing
deviations from a purely conductive thermal regime within sedimentary basins. The thermal regime of
the lithosphere in the East Carpathian bend and its foreland was analyzed, based on geothermal
measurements performed in 41 boreholes. The temperature-depth profiles show a large range of the
lateral variation of geothermal gradients, from 23 mKm-1 to 53 mKm-1, and an increase of the gradient
with depth, in the studied area. The increase of the temperature gradients with depth may be a
consequence of the presence of a fluid flow component, but it may also be explained by a decrease of
the thermal conductivity with depth which may follow from transition from wet to dry conditions or by
undercompaction. We modeled the thermal regime of the foreland of the Eastern Carpathians from the
point of view of groundwater flow in relation to the heat transfer. Depending on the flow strength, the
geothermal regime in the basin can be influenced, with cooling effects in recharge areas, and warming
effects in discharge areas. Using quantitative modeling techniques, models which take into account the
coupled effects of heat and migration of water given by topographic relief, buoyancy forces and
sediment compaction, would be constructed. The accuracy of models depends on hydrologic properties
of sediments.
Keywords: heat flow data, basin scale fluid flow, modeling