Romeu Vieira

Dr. Romeu Vieira

orcid

Research Focus & Metrics

Academic Career Length

18Years (2009-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
8 May 2017 in Geology
Verified
Journal Article
Closed access
PLPilar Lecumberri-Sanchez
Pilar Lecumberri-Sanchez
RVRomeu Vieira
Romeu Vieira
CHC.A. Heinrich
C.A. Heinrich
FPFilipe Pinto
Filipe Pinto
MWM. Wӓlle
M. Wӓlle


21 March 2011 in American Mineralogist: Journal of Earth and Planetary Materials
Verified
Journal Article
Closed access
PDF file
RVRomeu Vieira
Romeu Vieira
EREncarnación Roda-Robles
Encarnación Roda-Robles
APAlfonso Pesquera
Alfonso Pesquera
ALALEXANDRE Lima
ALEXANDRE Lima
Field, textural, paragenetic, and chemical data for micas from pegmatites of the Fregeneda-Almendra pegmatitic field (Central-Iberian Zone) are used to characterize and evaluate their petrogenesis. These pegmatites show a zonal distribution from barren to evolved, with an increase in degree of evolution with increasing distance from the Mêda-Penedono-Lumbrales leucogranite. Five types of evolved pegmatites have been recognized: (1) petalite-rich, (2) spodumene-rich, (3) Li-mica + spodumene-rich, (4) Li-mica-rich, and (5) cassiterite-rich pegmatites, plus six types of barren and intermediate pegmatites. Representative micas from the different pegmatite types and from the leucogranite were analyzed for major and trace elements. All micas belong to the muscovite-lepidolite series. Lithium is incorporated into Li-micas via the Li3Al−1□−2 and Si2LiAl−3 substitutions, where □ represents vacancies. The Al4Si−3□−1 and Al2□1R2+−3 substitutions, where R2+ = (Fe + Mg + Mn), account for the compositional variability of micas from the Li-mica-free pegmatites. The Li, Rb, Cs, Be, Ta, and Nb contents of micas increase in the order: leucogranites and barren pegmatites < intermediate pegmatites < spodumene-bearing and petalite-bearing dikes < Li-mica-bearing pegmatites. The Ba content decreases in the same order, and Sn and Zn are relatively abundant in the intermediate pegmatites. These variations are consistent with rare-element enrichment via fractionation processes combined with partitioning of rare elements from the pegmatite melt into the minerals and volatile phases. However, some pegmatite types occurring in this area, such as the cassiterite-rich dikes, do not seem to form part of the same evolutionary trend.

1 February 2016 in Mineralogical Magazine
Verified
Journal Article
Open access
EREncarnación Roda-Robles
Encarnación Roda-Robles
APA. Pesquera
A. Pesquera
PGPedro P. Gil-Crespo
Pedro P. Gil-Crespo
RVRomeu Vieira
Romeu Vieira
ALALEXANDRE Lima
ALEXANDRE Lima
JTJ. Torres-Ruiz
J. Torres-Ruiz
Lithium mineralization is common in the Central Iberian Zone and, to a lesser extent, in the Galizia-Trás-OsMontes Zone of Spain and Portugal, occurring along a ∼500 km-long NNW-SSE striking belt. There are different styles of Li mineralization along this belt; they are mainly associated with aplite-pegmatite bodies and, to a much lesser extent, with veins of quartz and phosphate. Lithium mineralization in the Central Iberian Zone may be classified into four types: aplite-pegmatite dykes occurring in pegmatitic fields, Li mineralization associated with leucogranitic cupolas, beryl-phosphate pegmatites and quartz-montebrasite veins. The main Li minerals of these bodies include Li-mica, spodumene and/or petalite in the pegmatitic fields and leucogranitic cupolas; triphylite–lithiophilite in the beryl-phosphate pegmatites, and amblygonite–montebrasite in the quartz-montebrasite veins. The origin of these different styles of mineralization is considered to be related to differentiation of peraluminous melts, which were generated by partial melting of metasedimentary rocks during the Variscan orogeny. On the basis of paragenesis and chemical composition, the pegmatitic fields and Li mineralization associated with granitic cupolas record the highest fractionation levels, whereas the beryl-phosphate pegmatites and quartz-montebrasite veins show lower degrees of fractionation. There are a number of textural and mineralogical indicators for Li exploration in the Central Iberian Zone and in the Galizia-Trás-Os-Montes Zone, with the highest economic potential for Li being in the pegmatite fields.

1 June 2018 in Journal of Geochemical Exploration
Verified
Journal Article
Closed access
MGMario Goncalves
Mario Goncalves
Antonio Manuel Nunes MateusAntonio Manuel Nunes Mateus
Antonio Manuel Nunes Mateus
FPFilipe Pinto
Filipe Pinto
RVRomeu Vieira
Romeu Vieira