%0 Journal Article
%A Tejero López, Rosa
%A Ruiz Pérez, Javier
%T Thermal and mechanical structure of the centralIberian Peninsula lithosphere
%D 2002
%@ 0040-1951
%U https://hdl.handle.net/20.500.14352/56769
%X The central Iberian Peninsula (Spain) is made up of three main tectonic units: a mountain range, the Spanish Central Systemand two Tertiary basins (those of the rivers Duero and Tajo). These units are the result of widespread foreland deformation ofthe Iberian plate interior in response to Alpine convergence of European and African plates. The present study was designed toinvestigate thermal structure and rheological stratification in this region of central Spain. Surface heat flow has been describedto range from f80 to f60 mW m2. Highest surface heat flow values correspond to the Central System and northern part ofthe Tajo Basin. The relationship between elevation and thermal state was used to construct a one-dimensional thermal model.Mantle heat flow drops from 34 mW m2 (Duero Basin) to 27 mW m2 (Tajo Basin), and increases with diminishing surfaceheat flow. Strength predictions made by extrapolating experimental data indicate varying rheological stratification throughoutthe area. In general, in compression, ductile fields predominate in the middle and lower crusts and lithospheric mantle. Brittlebehaviour is restricted to the first f8 km of the upper crust and to a thin layer at the top of the middle crust. In tension, brittlelayers are slightly more extended, while the lower crust and lithospheric mantle remain ductile in the case of a wet peridotitecomposition. Discontinuities in brittle and ductile layer thickness determine lateral rheological anisotropy. Tectonic unitsroughly correspond to rheological domains. Brittle layers reach their maximum thickness beneath the Duero Basin and are ofleast thickness under the Tajo Basin, especially its northern area. Estimated total lithospheric strength shows a range from2.51012 to 81012 N m1 in compression, and from 1.31012 to 1.61012 N m1 in tension. Highest values were estimatedfor the Duero Basin. Depth versus frequency of earthquakes correlates well with strength predictions. Earthquake fociconcentrate mainly in the upper crust, showing a peak close to maximum strength depth. Most earthquakes occur in the southernmargin of the Central System and southeast Tajo Basin. Seismicity is related to major faults, some bounding rheologicaldomains. The Duero Basin is a relative quiescence zone characterised by higher total lithospheric strength than the remainingunits.
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