Heat Flow, Geotherms, Density and Lithosphere Thickness in SW of Iberia (South of Portugal)

Duque, Maria Rosa Alves

doi:10.31214/ijthfa.v1i1.9

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…Lithosphere thickness values of 96 Km were obtained. These values are similar to the values found in the South of Portugal (Duque, 2018a).…”

Section: Resultssupporting

confidence: 90%

Numerical Simulations of Terrestrial Heat Flow in the Beiras Region, Mainland Portugal

Duque

2020

ijthfa

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Numerical simulations of heat flow density have been made for ten localities in the Beiras region of central Portugal where observational data are absent. The procedure adopted is based on results of deep crustal geophysical surveys and consider that the heat flow measured at the surface of the Earth results from the addition of heat generated in the crust by radioactive sources to that coming from the mantle. Radioactive heat sources in the region are heterogeneous and heat flow values at the surface depends on the thickness of upper crustal layers. Geotherms were obtained considering heat flow by conduction in the vertical direction. The models employed make use of data derived from geophysical surveys of Moho depths and detailed results related with seismic velocity distribution in the crust. In addition, results of radiometric surveys were employed in deriving heat production values for upper layers of the crust. A value around 35 mW m-2 was assumed for heat flow from the mantle. The resulting heat flow density values are similar to those found for areas with similar tectonic characteristics in NW Africa and in Southern Portugal.

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“…Lithosphere thickness values of 96 Km were obtained. These values are similar to the values found in the South of Portugal (Duque, 2018a).…”

Section: Resultssupporting

confidence: 90%

Numerical Simulations of Terrestrial Heat Flow in the Beiras Region, Mainland Portugal

Duque

2020

ijthfa

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“…This difference of 22% between the maximum and minimum values may be explained by two different phenomena. The highest values of heat flow measured in the Iberian Pyrite Belt, in the Southern part of the territory needs the addition of another source of heat to that generated by radioactive decay (the heat generated in chemical reactions of Pyrite and water [11]). In the Northeastern part of the country a region with low content of radioactive elements can be seen in Gamma-Ray Charts [12].…”

Section: Heat Flow Density Data In Mainland Portugalmentioning

confidence: 99%

“…Different values of heat flow density measured/obtained at the surface are related to heat sources distribution in the crust and different thickness of formation layers with the sources. Heat from exothermic chemical reactions was added to the heat generated in the radioactive decay of Uranium Thorium and Potassium elements in some regions [11].…”

Section: Introductionmentioning

confidence: 99%

Geotermalny przepływ ciepła w Portugalii kontynentalnej

Duque

2024

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Heat flow density measurements in Portugal were made in boreholes used for mining prospecting. Heat flow density values in the sedimentary basins of the western and southern margins of the country were obtained using data from oil or gas prospecting works. Due to the scarcity of data in the central and northern regions of the country, numerical models based on some characteristics of the region were used to obtain more heat flow values. The total of heat flow values used in this work is 69, with 17 values obtained using numerical models, 36 obtained in boreholes and 16 obtained from oil/gas prospecting wells data. The analysis and location of these data allows to define different regions in the territory and characterize them using average values of heat flow density, temperature gradient and thermal conductivity. Statistical values with all the data in the territory are also presented.

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Heat Flow in SW of Galicia And NW of Portugal. The Interpretation of a Seismic Anomaly

Duque

2020

IOP Conf. Ser.: Earth Environ. Sci.

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Four heat flow density values and five temperature-depth profiles were obtained in a heterogeneous region considering heat flow by conduction in the vertical direction, and heat sources in the crust due to radioactivity decay. The heat produced in the upper layers of the crust was obtained based on gamma-ray charts and published data of laboratory radioactivity measurements on samples taken from the region. Seismic data were used to obtain the thickness of the different layers of the upper and middle crust and the depth of the Moho discontinuity considered coincident with the crust/mantle boundary. The heat flow at the surface is obtained by adding the heat flow from the mantle with the heat generated by the radioactive sources in the crust. The method was applied to a region with one measured heat flow density value (Ourense) and four points without any heat flow density measurement. A heat flow value from the mantle was obtained with Ourense data. Special attention was given to a region (A) with a seismic anomaly near the surface. The anomaly was explained by mass deficit near the surface that gives rise to an abnormal density value and an increase in seismic wave velocity values. The decrease in density is due to the presence of water in the region forming an aquifer. Geothermometer values obtained from samples of water in the thermal springs of Tuy (Spain) and Monção (Portugal) were used as the water temperature at the bottom of the aquifer. Isostatic balance in the region was considered to obtain density values and the amount of water in the region. Thermal conductivity and radioactivity heat source values in the region were obtained considering the amount of water in the region. Values from 86 to 97 mW/m2 were obtained using the same value of heat flow from the mantle. This is due to different values of heat produced in the crust due to different thickness layer values or/and to different heat production values.

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Heat Flow, Geotherms, Density and Lithosphere Thickness in SW of Iberia (South of Portugal)

Cited by 4 publications

References 16 publications

Numerical Simulations of Terrestrial Heat Flow in the Beiras Region, Mainland Portugal

Numerical Simulations of Terrestrial Heat Flow in the Beiras Region, Mainland Portugal

Geotermalny przepływ ciepła w Portugalii kontynentalnej

Heat Flow in SW of Galicia And NW of Portugal. The Interpretation of a Seismic Anomaly

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