Geothermal models of the crust and uppermost mantle of the Fennoscandian Shield in South Norway and the Danish Embayment

A narrow heat flow transition zone between the Fennoscandian Shield and the North Sea Basin has been investigated along a profile from the Precambrian of South Norway to the Danish Embayment in North Jylland. Along this profile the surface heat flow varies from about 42 mWm-2 (measured) in South Norway to 60–70 mWm-2 (estimated) in Denmark. Geothermal, seismic, gravity and other geophysical and geological data have formed the basis for construction of heat production and thermal conductivity models in the depth interval 0–50 km. The related steady-state temperatures and heat flow distributions are calculated by a numerical solution of the heat conduction equation in two dimensions. Three models are presented, a preferred model and two others which yield temperatures assumed to be close to the lowest and highest possible values. The preferred model gives temperatures of about 350 °C at the crust-mantle boundary in the Shield and approximately 700 °C beneath the Danish Embayment. These differences are associated with considerable variations in the heat flow from the mantle. In the main model variations from 16-17 mWm-2 in the shield region to about 40 mWm-2 in the Danish Embayment have been found. Some geophysical and petrological implications are discussed. In the sedimentary basin partial melting in the lower crust and at shallow depth in the uppermost mantle seems to be likely.           ARK: https://n2t.net/ark:/88439/y020204 Permalink: https://geophysicsjournal.com/article/254 &nbsp