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- Litoteca do LNEG Aljustrel, um espólio científico fundamental para a investigação da Faixa Piritosa Ibérica e da Zona de Ossa-MorenaPublication . Matos, João Xavier; Morais, Igor; Santos, Sara; Gonçalves, Pedro; Batista, Maria Joao; de Oliveira, Daniel Pipa Soares; Dias, Ruben PereiraSUMMARY: Since 2018 the LNEG’s Aljustrel drill core shed is dedicated to the southern Portugal collections distributed by Iberian Pyrite Belt (IPB) and Ossa-Morena Zone (OMZ). The archive includes exploration drill hole cores, soil, stream sediments and rock samples, technical reports, and a complete and detail map collection (1/5.000 and 1/25.000 scales), all organized in databases. Drill hole relog allow a better understanding of the subsurface being essential in stratigraphy, structural mapping, mineral exploration and metallogeny. Following the regional Smart Specialization Strategy defined by CCDR Alentejo to Geological Resources, the LNEG Aljustrel develops R&D programs dedicated to thematic mapping and mineral resources. Critical Raw Materials mineralizations are present at the archives like IPB VMS Cu-Zn-Pb(Au-Ag-Sn-Sb) and Fe-Mn deposits and OMZ sulphide-magnetite (Zn-Pb,Cu(Au)), magnetite and Cu(Au) veins. The preservation of the subsurface geological heritage is critical to the IPB and OMZ research and an institutional LNEG mission.
- Carta geoambiental da região da Grande BeiraPublication . Oliveira, José Tomás; Milisse, Dino; Daudi, Elias Félix; Ramalho, Elsa; Fernandes, Judite; Quental, Lídia; Batista, Maria Joao; Dias, Ruben Pereira; Ussene, Ussene Vasco; Magaia, Almiro; Muchanga, André; Muchibane, Aníbal; Zeferino, Cátia Lídia; Balate, Gabriel; Gomane, Gertrudes; Cune, Grácio; Rebêlo, Luís Pina; Nave, Silvia; Manhiça, Vladimiro; Pereira, Aurete
- Characterization of an Intraplate Seismogenic Zone Using Geophysical and Borehole Data: The Vila Franca de Xira Fault, PortugalPublication . Carvalho, João; Alves, Daniela; Cabral, João; Ghose, Ranajit; Borges, José Fernando; Dias, Ruben Pereira; Ramalho, Elsa; Caldeira, Bento; Casacão, J.; Leote, JaimeABSTRACT: The Vila Franca de Xira (VFX) fault is a regional fault zone located about 25 km northeast of Lisbon, affecting Neogene sediments. Recent shear-wave seismic studies show that this complex fault zone is buried beneath Holocene sediments and is deforming the alluvial cover, in agreement with a previous work that proposes the fault as the source of the 1531 Lower Tagus Valley earthquake. In this work, we corroborate these results using S-wave, P-wave, geoelectric, ground-penetrating radar and borehole data, confirming that the sediments deformed by several fault branches are of Upper Pleistocene to Holocene. Accumulated fault vertical offsets of about 3 m are estimated from the integrated interpretation of geophysical and borehole data, including 2D elastic seismic modeling, with an estimated resolution of about 0.5 m. The deformations affecting the Tagus alluvial sediments probably resulted from surface or near-surface rupture of the VFX fault during M similar to 7 earthquakes, reinforcing the fault as the seismogenic source of regional historical events, as in 1531, and highlighting the need for preparedness for the next event.
- A soil classification for seismic hazard assessment and mitigation of the AlgarvePublication . Carvalho, João P. F.; Dias, Ruben Pereira; Pinto, Carlos C.; Leote, Jaime; Victor, L. MendesThe Algarve province of Portugal is located near the E-W Eurasia-Africa plate boundary. It is characterized by a moderate seismicity, with some important historical earthquakes causing important damage and economical losses. Not only has it suffered the effects of large plate boundary events but also the impact of local onshore moderate-sized earthquake sources. The seismic hazard evaluation and mitigation of the area is therefore of great importance to the local populations and the large number of tourists that frequent the region. This paper focuses the evaluation of the most interesting and useful geotechnical near-surface parameters and a soil classification. The classification based upon the European Code 8 for civil engineering and SPT bedrock data, was carried out for land use planning and design of critical facilities. P-wave and S-wave seismic velocities were obtained through the acquisition, processing and interpretation refraction profiles. Hundreds of SPT parameters from available boreholes drilled for engineering and water supply were used and subsoil classification based on geophysical and geotechnical parameters is presented. Other parameters, such as Vp/Vs ratios and the Poisson coefficient were estimated and were computed to provide information for future site effect studies. The experimental procedure tested here is relatively fast, economical and easy to perform and can be useful to estimate soil microzoning and seismic hazard mapping in the absence of local earthquake records.
- Alterações pedogenéticas de idade indeterminada : Paleogénico-QuaternárioPublication . Dias, Ruben Pereira; Barbosa, Bernardo; Pais, João; Azerêdo, Ana Cristina; Pimentel, Nuno; Cabral, Maria Cristina
- Mação-Penhascoso laccolite granite: age and its implications, SW-Central-Iberian ZonePublication . Romão, José; Dunning, G. R.; Marcos, A.; Dias, Ruben Pereira; Ribeiro, AntónioO lacólito granítico de Mação-Penhascoso ocorre no bordo SE da Zona Centro-Ibérica próximo da fronteira com a Zona de Ossa Morena. Uma idade U/Pb (ID-TIMS) de 483 Ma foi obtida em zircões magmáticos da sua litofácies microgranítica. A Formação do Quartzito Armoricano (FQA) é condicionada pela sua intrusão e discordantemente recoberta pela Formação do Brejo Fundeiro de idade Oretaniana. Isto sugere que a FQA, já compactada, é do Tremadociano ou do Câmbrico superior. Concluímos que as fácies da FQA são diacrónicas entre o Câmbrico superior e o Arenigiano de SW para NE no terreno Ibérico, tendo sido alimentadas a partir de um promontório do Continente Gondwana.
- Geofísica aplicada à gestão da água subterrânea e ao ordenamento do território da cidade da BeiraPublication . Daudi, Elias Félix; Ramalho, Elsa; Fernandes, Judite; Batista, Maria Joao; Quental, Lídia; Dias, Ruben Pereira; Milisse, Dino; Ussene, Ussene Vasco; Oliveira, José Tomás; Cune, Grácio; Balate, Gabriel; Manhiça, Vítor
- Riscos geológicos e geologia urbanaPublication . Dias, Ruben Pereira
- Improving the knowledge on seismogenic sources in Lower Tagus Valley for seismic hazard purposesPublication . Carvalho, João; Pinto, Carlos C.; Costa, M.; Duarte, H.; Terrinha, Pedro; Rabeh, Taha; Borges, José Fernando; Dias, Ruben Pereira; Caldeira, Bento
- Dados Copernicus na caracterização e monitorização de recursos geológicos em Portugal [Resumo]Publication . Quental, Lídia; Gonçalves, Pedro; de Oliveira, Daniel Pipa Soares; Patinha, Pedro; Dias, Ruben Pereira