HEAT-FLOW IN THE BALTIC SHIELD - RESULTS OF THE LITHOSPHERIC GEOTHERMAL MODELING

The results of heat flow measurements performed within the Baltic Shie ld and in its closest neighbourhood are reviewed. The regional distrib ution of the heat flow density is presented as a heat flow map. The ch aracteristic heat flow density amounts to 35-40 mW m(-2) and is notabl y smaller than heat flow in the surrounding areas. The radiogenic heat production within the crust contributes to the observed surface heat flow by about 15-20 mW m(-2). This permits to estimate the Moho heat f low in the most stable parts of the shield to about 20 mW m(-2), and o ver 25-30 mW m(-2) in the surrounding platform to the south and east. Relatively low Moho temperatures of 350-500 degrees C characterize the crust/mantle boundary of the shield, increasing to 600-700 degrees C beneath the shield margins. The thermal thickness of the lithosphere o f the shield can attain more than 200 km.