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Geometria de rochas granitóides através da inversão de dados de campo-potencial na região centro de Portugal
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Advisor(s)
Abstract(s)
RESUMO: O principal objectivo deste trabalho é conhecer em profundidade
a geometria das rochas granitóides e, deste modo, contribuir com dados
relevantes para a avaliação do potencial geotérmico na região. A área em
estudo localiza-se na região centro de Portugal, onde afloram rochas
granitóides variscas pertencentes ao batólito granítico das Beiras, que intruíram
as sequências metassedimentares do Complexo Xisto-Grauváquico. Para
tal, realizaram-se campanhas de prospecção geofísica, por métodos
gravimétricos e magnéticos, que permitem obter as cartas das anomalias de
campo-potencial. Estas anomalias são modeladas em conjunto,
demonstrando que a fracturação regional condiciona a geometria dos granitos e da sequência encaixante. A estimativa da profundidade média e
máxima dos corpos graníticos é de 5 km e de 11,6 km. O estudo
desenvolvido mostra que as áreas com maior potencial geotérmico e mais
promissoras para as aplicações geotérmicas, localizam-se em zonas de
fraqueza estrutural e onde os corpos graníticos apresentam maior espessura.
ABSTRACT: The main goal of this work is to obtain a better understanding of the subsurface geometry of the granitic rocks in the central Portugal region for the assessment of the geothermal potential of the region. The study area is located in the Centro Iberian Zone where the Beiras granite batholiths outcrop. These granitoids were emplaced into the metasedimentary sequences of the Complexo Xisto-Grauváquico (CXG) and are attributed to the magmatic activity associated to the post-collisional stages of the Variscan orogeny during the D3 stage. To achieve the study goal, magnetic and gravimetric surveys where performed in order to obtain the Bouguer and magnetic anomalies. Considering and integrating all the available geological and geophysical data the mentioned potential fields were simultaneously modelled. In this way it was possible to characterize the subsurface geometry of the granitic bodies in the region (Tábua-Santa Comba Dão (TSCD) and Serra da Estrela (SE) plutons). The modelling results show that the regional tectonic setting controls the geometry of the granitic rocks as well as the structure of the CXG sequence. Through the modelling of the potential field the overall geometry of the granitic bodies in the study area was obtained. The modelled average depth for the granitic bodies is 5 km, with a maximum depth of 11.6 km. This study demonstrates that the areas with greatest potential for future geothermal applications are located in zones of structural weakness and where the granitic bodies have a greater thickness.
ABSTRACT: The main goal of this work is to obtain a better understanding of the subsurface geometry of the granitic rocks in the central Portugal region for the assessment of the geothermal potential of the region. The study area is located in the Centro Iberian Zone where the Beiras granite batholiths outcrop. These granitoids were emplaced into the metasedimentary sequences of the Complexo Xisto-Grauváquico (CXG) and are attributed to the magmatic activity associated to the post-collisional stages of the Variscan orogeny during the D3 stage. To achieve the study goal, magnetic and gravimetric surveys where performed in order to obtain the Bouguer and magnetic anomalies. Considering and integrating all the available geological and geophysical data the mentioned potential fields were simultaneously modelled. In this way it was possible to characterize the subsurface geometry of the granitic bodies in the region (Tábua-Santa Comba Dão (TSCD) and Serra da Estrela (SE) plutons). The modelling results show that the regional tectonic setting controls the geometry of the granitic rocks as well as the structure of the CXG sequence. Through the modelling of the potential field the overall geometry of the granitic bodies in the study area was obtained. The modelled average depth for the granitic bodies is 5 km, with a maximum depth of 11.6 km. This study demonstrates that the areas with greatest potential for future geothermal applications are located in zones of structural weakness and where the granitic bodies have a greater thickness.
Description
Keywords
Anomalia de Bouguer Anomalia magnética Inversão Granitos Potencial geotérmico Bouguer anomaly Magnetic anomaly Inversion Granites Geothermal potential
Citation
Machadinho, Figueiredo & Pereira 2020, ‘Geometria de rochas granitóides através da inversão de dados de campo-potencial na região centro de Portugal’, Comunicações Geológicas, vol. 107, nº 1 (especial), pp. 83-87. https://doi.org/10.34637/a8h0-2m98
Publisher
LNEG - Laboratório Nacional de Energia e Geologia