Heat flow, heat production, and lithospheric thermal regime in the Iberian Peninsula

Fernàndez, M.; Marzán, Ignacio; Correia, A.; Ramalho, Elsa Cristina

doi:10.1016/s0040-1951(98)00029-8

Cited by 190 publications

(186 citation statements)

References 40 publications

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“…As mentioned above, granitic rocks outcrop extensively in the Central System, while geophysical data suggest that metamorphic rocks prevail in the basement underlying the Duero and Tajo basins (Aeroservice, 1964;Querol, 1989). Average heat production for granitic rocks has been quoted as 3.26 AW m À3 , higher than values for metamorphic rocks, which range from f 0.8 to f 2.3 AW m À3 (Fernández et al, 1998). Thus, relatively low differences in heat flow values may be related to upper crust composition (Lachenbruch, 1968(Lachenbruch, , 1970.…”

Section: Thermal Modellingmentioning

confidence: 98%

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Thermal and mechanical structure of the central Iberian Peninsula lithosphere

Tejero

Ruíz

2002

Tectonophysics

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The central Iberian Peninsula (Spain) is made up of three main tectonic units: a mountain range, the Spanish Central System and two Tertiary basins (those of the rivers Duero and Tajo). These units are the result of widespread foreland deformation of the Iberian plate interior in response to Alpine convergence of European and African plates. The present study was designed to investigate thermal structure and rheological stratification in this region of central Spain. Surface heat flow has been described to range from f 80 to f 60 mW m À2 . Highest surface heat flow values correspond to the Central System and northern part of the 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 m À2 (Duero Basin) to 27 mW m À2 (Tajo Basin), and increases with diminishing surface heat flow. Strength predictions made by extrapolating experimental data indicate varying rheological stratification throughout the area. In general, in compression, ductile fields predominate in the middle and lower crusts and lithospheric mantle. Brittle behaviour is restricted to the first f 8 km of the upper crust and to a thin layer at the top of the middle crust. In tension, brittle layers are slightly more extended, while the lower crust and lithospheric mantle remain ductile in the case of a wet peridotite composition. Discontinuities in brittle and ductile layer thickness determine lateral rheological anisotropy. Tectonic units roughly correspond to rheological domains. Brittle layers reach their maximum thickness beneath the Duero Basin and are of least thickness under the Tajo Basin, especially its northern area. Estimated total lithospheric strength shows a range from 2.5Â10 12 to 8Â10 12 N m À1 in compression, and from 1.3Â10 12 to 1.6Â10 12 N m À1 in tension. Highest values were estimated for the Duero Basin. Depth versus frequency of earthquakes correlates well with strength predictions. Earthquake foci concentrate mainly in the upper crust, showing a peak close to maximum strength depth. Most earthquakes occur in the southern margin of the Central System and southeast Tajo Basin. Seismicity is related to major faults, some bounding rheological domains. The Duero Basin is a relative quiescence zone characterised by higher total lithospheric strength than the remaining units. D

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Section: Thermal Modellingmentioning

confidence: 98%

“…Thus, heat production needs to be known to estimate geotherms. Fernández et al (1998) recently published updated heat flow and heat production maps of the Iberian Peninsula. Despite irregular sampling surface distribution, the heat flow map of the Iberian Peninsula indicates variations in the study area.…”

Section: Thermal Modellingmentioning

confidence: 99%

Thermal and mechanical structure of the central Iberian Peninsula lithosphere

Tejero

Ruíz

2002

Tectonophysics

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“…The sedimentary cover has a thickness of ~2500 m in the Duero Basin (Gómez- Ortiz et al 2005a;De Vicente et al, 2007), while it reaches ~3400 m in the Madrid basin (Racero Baena 1988;Querol Müller 1989;Tejero et al 1996;Gómez-Ortiz et al 2005a;De Vicente et al, 2007;De Vicente and Muñoz,Martín, 2012). The lithosphere-asthenosphere boundary is located at a mean depth of ~100 km in the peninsular interior (Banda et al, 1981;Fernàndez et al, 1998;Tejero and Ruiz 2002;Martín-Velázquez and De Vicente, 2012).…”

Section: Structure Composition and Heat Flowmentioning

confidence: 99%

“…The surface heat flow ranges from 60 to 85 mW m -2 , with the highest values in the Central System (Fernàndez et al, 1998;Jiménez-Díaz et al, 2012). The heat production in the upper crust ranges from 0.2-4.7 µW m -3 in the granitic rocks and from 0.8-2.3 µW m -3 in the metamorphic rocks (Fernàn-dez et al 1998;Jiménez-Díaz et al, 2012), whereas it barely exceeds 1 µW m -3 in the lower crust (Villaseca et al, 1999(Villaseca et al, , 2005Jiménez-Díaz et al, 2012).…”

Section: Structure Composition and Heat Flowmentioning

confidence: 99%

“…According to the complex stress conditions in the peninsular centre, brittle strength [3] was calculated in thrust, strike-slip and normal fault regimes, and thus α was respectively 3.0, 1.2 and 0.75, assuming a coefficient of friction 0.75 (Ranalli, 1995). A hydrostatic pore fluid pressure f P was assumed in (Fernàndez et al, 1998;Tejero and Ruiz, 2002;Villaseca et al, 2005;Villaseca and Orejana, 2008;Jiménez-Díaz et al, 2012), and the slight discrepancies are caused by differences in the lithospheric structures and thermal parameters.…”

Section: Model and Materials Parametersmentioning

confidence: 99%

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Strength of the Iberian intraplate lithosphere: Cenozoic deformations and seismicity

Martín-Velázquez

Muñoz

Gómez-Ortíz

et al. 2016

Journal of Iberian Geology

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Previous studies about the strength of the lithosphere in the center of Iberia fail to resolve the depth of earthquakes because of the rheological uncertainties. Therefore, new contributions are considered (the crustal structure from a density model) and several parameters (tectonic regime, mantle rheology, strain rate) are checked in this paper to properly examine the role of lithospheric strength in the intraplate seismicity and the Cenozoic evolution. The strength distribution with depth, the integrated strength, the effective elastic thickness and the seismogenic thickness have been calculated by a finite element modelling of the lithosphere across the Central System mountain range and the bordering Duero and Madrid sedimentary basins. Only a dry mantle under strike-slip/extension and a strain rate of 10 -15 s , causes a strong lithosphere. The integrated strength and the elastic thickness are lower in the mountain chain than in the basins. This heterogeneity has been maintained since the Cenozoic and determine the mountain uplift and the biharmonic folding of the Iberian lithosphere during the Alpine deformations. The seismogenic thickness bounds the seismic activity in the upper-middle crust, and the decreasing crustal strength from the Duero Basin towards the Madrid Basin is related to a parallel increase in Plio-Quaternary deformations and seismicity. However, elasto-plastic modelling shows that current African-Eurasian convergence is resolved elastically or ductilely, which accounts for the low seismicity recorded in this region.Keywords: lithospheric strength, effective elastic thickness, seismogenic thickness, Iberia, finite element modelling ResumenLos estudios previos sobre resistencia de la litosfera en el centro de Iberia no logran resolver la profundidad de los terremotos debido a las incertidumbres reológicas. Por eso, en este trabajo se han considerado nuevas contribuciones (estructura cortical obtenida de un modelo de densidad) y se han comprobado varios parámetros (régimen tectónico, reología del manto, tasa de deformación) para examinar adecuadamente el papel de la resistencia de la litosfera en la sismicidad intraplaca y en la evolución Cenozoica. Mediante una modelización de elementos finitos, se ha calculado la distribución de la resistencia con la profundidad, la resistencia integrada, el espesor elástico efectivo y el espesor sismogénico en una sección litosférica que atraviesa la cadena montañosa del Sistema Central y las cuencas sedimentarias del Duero y Madrid. Sólo un manto seco en desgarre/extensión y una tasa de deformación de 10 -15 s -1, o bajo extensión y 10 -16 s -1 , origina una litosfera resistente. La resistencia integrada y el espesor elástico son más bajos en el sistema montañoso que en las cuencas. Estas anisotropías se han mantenido desde el Cenozoico y determinan el levantamiento de la cadena y el plegamiento biarmónico de la litosfera Ibérica durante las deformaciones alpinas. El espesor sismogénico limita la actividad sísmica en la corteza superior-media, y l...

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Vertical GPS ground motion rates in the Euro‐Mediterranean region: New evidence of velocity gradients at different spatial scales along the Nubia‐Eurasia plate boundary

Faccenna²,

et al. 2013

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[1] We use 2.5 to 14 years long position time series from >800 continuous Global Positioning System (GPS) stations to study vertical deformation rates in the Euro-Mediterranean region. We estimate and remove common mode errors in position time series using a principal component analysis, obtaining a significant gain in the signal-to-noise ratio of the displacements data. Following the results of a maximum likelihood estimation analysis, which gives a mean spectral index~À0.7, we adopt a power law + white noise stochastic model in estimating the final vertical rates and find 95% of the velocities within ±2 mm/yr, with uncertainties from filtered time series~40% smaller than from the unfiltered ones. We highlight the presence of statistically significant velocity gradients where the stations density is higher. We find undulations of the vertical velocity field at different spatial scales both in tectonically active regions, like eastern Alps, Apennines, and eastern Mediterranean, and in regions characterized by a low or negligible tectonic activity, like central Iberia and western Alps. A correlation between smooth vertical velocities and topographic features is apparent in many sectors of the study area. Glacial isostatic adjustment and weathering processes do not completely explain the measured rates, and a combination of active tectonics and deep-seated geodynamic processes must be invoked. Excluding areas where localized processes are likely, or where subduction processes may be active, mantle dynamics is the most likely process, but regional mantle modeling is required for a better understanding.

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Heat flow, heat production, and lithospheric thermal regime in the Iberian Peninsula

Cited by 190 publications

References 40 publications

Thermal and mechanical structure of the central Iberian Peninsula lithosphere

Thermal and mechanical structure of the central Iberian Peninsula lithosphere

Strength of the Iberian intraplate lithosphere: Cenozoic deformations and seismicity

Vertical GPS ground motion rates in the Euro‐Mediterranean region: New evidence of velocity gradients at different spatial scales along the Nubia‐Eurasia plate boundary

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