Role of Variscan granites in the genesis of Freixo de Numao W(Sn) district (Northern Portugal)

• Type: Article in International Scientific Journal
• Date: 2022

Authors

Gonçalves, A (Author) Other; Sant'Ovaia, H (Author) FCUP; Noronha, F (Author) FCUP

Journal

Title: Journal Of Iberian Geology

Vol. 48

Pages: 309-353

ISSN: 1698-6180

Publisher: Springer Nature

Indexing

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Other information

Authenticus ID: P-00W-ZMT

DOI: 10.1007/s41513-022-00195-2

Abstract (EN): Geochemistry of granites from Vila Nova de Foz Coa coupled with fieldwork, metallography, and magnetic susceptibility (K-m) studies provide a better knowledge about geology, magmatic differentiation degree, and relationships with tungsten and tin mineralizations. The region is characterized by three small isolated circumscribed Variscan plutons (Custoias, Numao and Freixo de Numao) intruding Lower Cambrian metasediments from Schist Greywacke Complex (SGC). Custoias (CG) is a homogeneous pluton, Numao pluton is composed of four granites (Cachao Arnozelo, CAG; Numao, NG; Arnozelo, AG and Quinta Silva, QSG), and Freixo de Numao pluton is composed of Freixo de Numao (FNG) and Frei Tome (FTG) granites. The geochemistry showed two magmatic differentiation trends: (a) FNG and CAG; and (b) NG, CG, FTG, AG and aplite. K-m decreases with the increasing magmatic differentiation. The high values of Sn, Rb, Nb and W and low values of Sr, Zn, Zr, Ba and Th allowed distinguishing Sn-bearing granites. A single W and Sn mineralizing episode contemporary with the emplacement and magmatic fractionation of peraluminous magmas was established. The Sn mineralization is related to late magmatic phases and W is related to hydrothermal fluids. The similarities between the Freixo de Numao W(Sn) district and other mineralizations inside the Douro Scheelite Belt, support identical genetic links to mineralizations, with an origin related to late- to post-D-3 peraluminous granites and the deposition of W-bearing minerals controlled by the interaction hydrothermal fluids-SGC formations with distinct compositions.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 45