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Notes: Steady-state heat conduction modelling was carried out to calculate the crustal temperature field and thermal lithosphere thickness in the Baltic shield. The radiogenic sources at the surface were fixed depending on the age of the crust. Below the uppermost 10 kilometres, a relationship between heat generation and P-wave velocity was applied and seismic structure was used to define individual crustal blocks of specific thermal parameters. Small-scale surface heat-flow density anomalies are interpreted as lateral variations of heat generation within the upper part of the crust, whereas the large anomaly in the southern part of the shield is attributed to an anomalously high mantle heat-flow density. The results are shown on maps outlining mantle heat-flow density, Moho temperature and thermal lithosphere thickness. A relationship between subcrustal temperature and Moho depth was found, except for southern Sweden. The lithospheric thickness is found to exceed 200 km in the Bothnian Gulf–northern-central Finland and part of the Kola peninsula, where temperatures at the Moho are less than 500 °C; the temperature gradient at the top of the mantle has, on the average, a value of 7.5 mK m−1 and the mantle heat-flow density varies from 19 to 25 mW m−2. Towards the south, the lithospheric thickness decreases until it attains a value lower than 100 km under southern Sweden. In this latter area, the Moho temperature and mantle heat-flow density are remarkably high, 700°–900°C and 30–45 mW m−2, respectively, as well as the temperature gradient, which amounts to 10 mK m−1.

Notes: The structural setting beneath the Ligurian Sea resuJts from several tectonic events reflected in the nature of the crust. The central-western sector, called the Ligurian basin, is part of the northwestern Mediterranean. It is a marginal basin that was generated in Oligocene-Miocene time by subduction of the Adriatic plate beneath the European plate and by the eastward drift of the Corsica-Sardinia block. The eastern sector belongs to the Tyrrhenian basin system and is characterized by extensional activity which since Tortonian time superimposed an earlier compressional regime. Our effort has been addressed in particular towards simplifying the complex nature of the crust of the Ligurian basin by modelling its genesis using uniform extension and sea-floor depth variation with age. In the rift stage of the basin's evolution, the initial subsidence reaches the isostatic equilibrium level of the asthenosphere by a thinning factor of 3.15. The additional passive process, corresponding to the cooling of the lithosphere since 21 Ma, leads to a total tectonic subsidence of 3.4 km, representing the boundary of the extended continental crust. For values up to 4.1 km a transitional-type crust is expected, whereas for higher tectonic subsidence values a typical oceanic crust should exist. After setting these constraints, the boundaries of the different crust types have been drawn based on total tectonic subsidence observations deduced from bathymetry and post-rift sediment thickness. Although there is a general agreement with the previous reconstructions deduced from other experimental data, the oceanic realm has wider extent and more complex shape. The northernmost part of this realm shows crust of sub-oceanic type altemating basement highs with lower subsidence values. The observed surface heat flux is consistent with the predicted geothermal held in the Alpine-Provençal continental margin and in the oceanic domain. However, a characteristic thermal asymmetry is clearly visible astride the basin, due to the enhanced heat flux of the Corsica margin. Even if the uniform extension model accounts well at a regional level for the present basement depth, a remarkable tectonic subsidence excess has been found in the Alpine-Provençal continental margin. This evidence agrees with the reprise in compression of the margin; the direction of the greatest principal stress is N120°E on average.