67 documents found, page 1 of 7
Strain partitioning in transpression; a major feature in the evolution of the I...
Dias, Rui; Araújo, Alexandre; Couto, Helena; Cruz, Cláudia; Ferreira, Joana; Gonçalves, Ana Marta; Lima, Alexandre; Lopes, Luís; Moreira, NoelAs the wavy pattern of fold belts is a common feature, since its recognition, the transpressive regimes were expected to be a pervasive mechanism on their evolution. Nevertheless, even in regions where oblique shortening is inferred, typical structures of transpression (e.g. transected cleavage and en echelon folds, shear or veins) are often absent. Instead, what is frequently observed is the juxtaposition of n...
Caracterização mineralógica do jazigo de ferro de Vila Cova (Marão)
Lopes Dias, Joana Mafalda; Vianez, Ricardo; Sant'Ovaia, Helena; Guedes, Alexandra; Cruz, Cláudia; Ferreira, Joana; Noronha, FernandoRESUMO: A caracterização mineralógica de amostras do jazigo de Vila Cova, situado no norte de Portugal, foi realizada a partir do estudo petrográfico, metalográfico, de catodoluminescência e de microscopia eletrónica de varrimento com espectroscopia por dispersão de energias. Assim, foram identificados minerais como quartzo, clorite, magnetite, pirite, arsenopirite, calcopirite, galena, tetradimite, rútilo, zir...
Caracterização mineralógica do minério de ferro dos jazigos de Cabeço de Mua e ...
Vianez, Ricardo; Lopes Dias, Joana Mafalda; Guedes, Alexandra; Sant'Ovaia, Helena; Ferreira, Joana; Cruz, Cláudia; Noronha, FernandoRESUMO: tecnologia e das infraestruturas de um país. Com o intuito de melhor conhecer os minérios de ferro de Portugal, especificamente dos jazigos de Cabeço da Mua e da Carvalhosa, foram efetuados estudos petrográficos, metalográficos e de microscopia eletrónica de varrimento com espetroscopia por dispersão de energias (MEV-EDE). Os minerais principais identificados foram quartzo, hematite e goetite, havendo a...
Tectonic Evolution of Portuguese Variscan Granites: Insights from Anisotropy of...
Sant'Ovaia, Helena; Cruz, Claudia; Gonçalves, Ana; Nogueira, Pedro; Noronha, FernandoThe anisotropy of magnetic susceptibility (AMS) data from 19 Portuguese Variscan granite plutons, spanning 320–296 Ma, has been consolidated and reinterpreted. This comprehensive dataset, including 876 sampling sites and over 7,080 AMS measurements, provides new insights into the tectonic evolution of the region. Magnetic susceptibility (Km) values range from 30 to 10,436 × 10 SI, with most granites exhibiting ...
Variscan plutonism in the geodynamic evolution of the central Iberian zone of P...
Cruz, Cláudia; Sant’Ovaia, Helena; Martins, Helena C. B.; Antunes, Isabel Margarida Horta Ribeiro; Rocha, Armando; Noronha, FernandoA multidisciplinary analysis of the Pennsylvanian Castelo Branco pluton of Central Iberian Zone (Iberian Variscan belt) was made, focusing on its magnetic behavior and fabric, microstructures, microfractures, and radiometric and gravimetric anomalies. The findings reveal that the Castelo Branco pluton is an ilmenite-type granite, characterized by low magnetic susceptibility values. The petrographic observations...
New insights from an emplacement model for the Santa Eulália Plutonic Complex (...
Cruz, Claudia; Nogueira, Pedro; Máximo, Jaime; Noronha, Fernando; Sant'Ovaia, HelenaThe Santa Eulália Plutonic Complex is formed by two main granites: G0 and G1. The G0 granite hosts metasedimentary carbonate and pelitic rocks (roof pendants) and elongated masses of mafic–intermediate rocks (the M-group). The host rocks form a diverse sequence of igneous, metasedimentary and metamorphic rocks. The study area is constrained by Variscan structures formed in a transpressional/transtensional sinis...
Combining Δ18o Isotope Data and In-Situ La-Icp-Ms Trace Element Analysis of Mag...
Maia, Miguel; Barrulas, Pedro; Nogueira, Pedro; Mirão, José; Noronha, FernandoThe Ossa-Morena Zone (OMZ, SW of the Iberian Peninsula) is a geotectonic domain that comprises a set of diversified ore deposits formed from Cambrian to Carboniferous-Permian ages. The Montemor-o-Novo – Ficalho Fe-Zn-(Pb) belt was a productive mining sector until the first half of the 20th century with potential for future mineral exploration, although the mechanisms responsible for ore deposition are, in some ...
Geodiversity Assessment Through the Évora–Montemor-o-Novo Region: on the Scope ...
Maia, Mi; Nogueira, Pedro; Mirão, José; Noronha, FernandoThe SW of Iberia registers diverse examples of mining remnants from activities that ceased during the twentieth century, namely in the Ossa-Morena Zone. Such activities exposed outcrops that are part of the mining heritage of the Alentejo region (Portugal), and examples of that are found throughout the Évora–Montemor-o-Novo region at the ancient Montemor- o-Novo iron mines. GeSologically, the area is comprised ...
In situ LA-ICP-MS trace element analysis of magnetite as a vector towards miner...
Maia, Miguel; Barrulas, Pedro; Nogueira, Pedro; Mirão, José; Noronha, FernandoThe Azenhas and Alvito Fe-deposits are located at SW of the Iberian Variscan belt, in a wide Fe-Zn ore district (Montemor-Ficalho Belt), part of the Ossa-Morena Zone. Both deposits are dominantly composed of magnetite ores that display distinct ore formation processes and, at the Azenhas deposit, massive magnetite ores are mainly hosted in amphibolites (Middle Cambrian – Ordovician), with a genesis arguably ass...
Ore Geology Reviews 142 (2022) 104736 Available online 3 February 2022 0169-136...
Maia, Miguel; Roseiro, José; Nogueira, Pedro; Noronha, Fernando; Fuertes-Fuente, Mercedes; Cepedal, Antonia; Mirão, JoséThe Escoural gold district belongs to the Montemor-Ficalho metallogenic belt which is part of the Portuguese section of Ossa-Morena Zone (OMZ), at the SW of Iberia. The Escoural gold district includes twelve gold pros- pects and/or deposits largely controlled by the NW-SE Montemor-o-Novo Shear Zone (MNSZ) and associated fault zones, extending for approximately 30 km. Ubiquitously, gold-arsenopyrite-loellingite ...