Hydrothermal alteration of the Beira schists around the W-Sn specialised Regoufe granite, NW Portugal

Haar, A.J. van de; Vriend, S.P.; Gaans, P.F.M. van

doi:10.1016/0375-6742(93)90029-l

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…This relationship was confirmed by the trace element composition of the granite, which is extremely enriched in Sn, W, Li, Cs, P, Ta, Rb and F in comparison with similar low-Ca granites (Vriend et al, 1985). In addition, Van de Haar et al (1993) demonstrated that the slates within the contact metamorphic aureole are enriched in Sn, F, B, W, Be, Cs and Rb relative to the average Beira slate composition.…”

Section: Geology Of the Regoufe Areamentioning

confidence: 67%

Superimposed folding and W-Sn vein-type mineralisation in the Central Iberian Zone associated with late-Variscan oroclinal buckling: A structural analysis from the Regoufe area (Portugal)

2018

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The Cantabrian orocline is a major orocline that bends the Variscan belt of Western Europe. Despite a wealth of studies, its timing and relationship with the late-Variscan folding stages in the Iberian Massif are still debated. This study provides an integrated structural analysis of the Variscan fold generations and associated W-Sn bearing vein systems within the southern Central Iberian Zone (Regoufe, Portugal), giving insight into their kinematic relationship with oroclinal buckling. Two superimposed fold generations with mutually parallel, steep to vertical fold axes have been identified. Isoclinal F1 folds with E-W striking axial planes formed during coaxial shortening and are spatially localised. F3 folds with NW-SE axial planes are associated with late-Variscan transpressional deformation and constrain the structural outline of the major folds. Temporal and kinematic considerations indicate that vertical-axis, asymmetric F3 folding corresponds with the expected deformation style within the southern limb of the Cantabrian orocline. The Regoufe area is characterised by two types of W-Sn vein-type mineralisation. Granite-hosted hydrothermal quartz veins show a concentric distribution and are associated with the stress regime during granite emplacement. The vein system within the metasedimentary host rock, however, is emplaced along a regional, subhorizontal cross-fold joint system. This cross-fold joint system developed orthogonal to the subvertical F3 fold axes, and is interpreted to be coeval with oroclinal buckling. These results impact the understanding of (i) the relative significance and geometry of the main deformation stages in the Iberian massif, reconciling the timing and kinematics of F3 regional folding with oroclinal buckling, and (ii) the kinematic relationship between late-to postorogenic deformation and W-Sn veintype mineralisation.

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Section: Geology Of the Regoufe Areamentioning

confidence: 67%

Superimposed folding and W-Sn vein-type mineralisation in the Central Iberian Zone associated with late-Variscan oroclinal buckling: A structural analysis from the Regoufe area (Portugal)

2018

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“…This granitic intrusion induced a medium-to low-grade contact metamorphism aureole in the country metasedimentary rocks of the Dúrico-Beirão Supergroup (mainly composed by phyllites and metagreywackes), which is materialised by the occurrence of biotite and phyllitic material in the low-grade regional metamorphic rocks [21]. The final stages of the granitic intrusion were characterised by hydrothermal processes that led to the precipitation of W-Sn ores in the quartz veins [21,24] and also caused hydrothermal alteration in both granite [21,24] and metasedimentary rocks [25].…”

Section: Geological Settingmentioning

confidence: 99%

Environmental Impact Assessment in the Former Mining Area of Regoufe (Arouca, Portugal): Contributions to Future Remediation Measures

Durães

Portela

Sousa

et al. 2021

IJERPH

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The W-Sn Regoufe mine, closed since the 1970s, was once intensively exploited for tungsten concentrates. Throughout its activity, considerable amounts of arsenopyrite-rich mine wastes were produced and, to this day, are still exposed to weathering conditions. Thus, this work aims at assessing soil contamination, using a combination of chemical, physicochemical and mineralogical analyses and sequential selective chemical extraction of the main potentially toxic elements (PTEs) in topsoils. Results show that Regoufe soils are enriched in most of the PTEs associated with the ore assemblage, but As and Cd contents far outstrip both international and national guidelines. The estimated contamination factor reveals that 67% of soil samples are classified as highly to ultra-highly contaminated. Similar distribution patterns, with the main focus around the unsealed mine adits, are observed when spatially projecting the modified degree of contamination (mCd) and arsenic contents. Fe-oxyhydroxides and organic matter demonstrate to have a preponderant role in the retention of Cd and As. In fact, despite the high PTE contents in soils, local surface waters are characterised by low metal(loid) contents and nearly neutral pH, with PTE concentrations below national thresholds for irrigation waters.

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Geochemistry of stratabound scheelite mineralisation and associated calc-silicate rocks from Chitral, NE Hindu Kush, Pakistan

2016

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Hydrothermal alteration of the Beira schists around the W-Sn specialised Regoufe granite, NW Portugal

Cited by 4 publications

References 14 publications

Superimposed folding and W-Sn vein-type mineralisation in the Central Iberian Zone associated with late-Variscan oroclinal buckling: A structural analysis from the Regoufe area (Portugal)

Superimposed folding and W-Sn vein-type mineralisation in the Central Iberian Zone associated with late-Variscan oroclinal buckling: A structural analysis from the Regoufe area (Portugal)

Environmental Impact Assessment in the Former Mining Area of Regoufe (Arouca, Portugal): Contributions to Future Remediation Measures

Geochemistry of stratabound scheelite mineralisation and associated calc-silicate rocks from Chitral, NE Hindu Kush, Pakistan

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