Petrogenetic constraints on the felsic vein magmatism in northern Portugal based on petrological and geochemical data

• Type: Article in International Scientific Journal
• Date: 2021

Authors

Oliveira, AJT (Author) Other; H. C. B. Martins (Author) FCUP; Sant'Ovaia, H (Author) FCUP

Journal

Title: Comptes Rendus - Geoscience

Vol. 353

Pages: 377-398

ISSN: 1631-0713

Publisher: Academie des Sciences

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 1 Citation

Other information

Authenticus ID: P-00V-Z3W

DOI: 10.5802/crgeos.100

Abstract (EN): Three of the largest granite porphyries of northern Portugal were studied to improve current knowledge on the regional felsic vein hypabyssal magmatism. All porphyries exhibit microcrystalline groundmasses of variable granularity (composed of quartz, K-feldspar, and muscovite), quartz, K-feldspar, plagioclase, biotite, and cordierite phenocrysts, antirapakivi and rapakivi feldspars, embayments in quartz, and enrichments in rare metal incompatible elements. The veins were emplaced along fractures generated during the last phase of the Variscan orogeny. Textural features were presumably conditioned by fast cooling, volatile loss, subsolidus annealing, and the magnitude of thermal contrasts at the time of emplacement. All veins were altered by subsolidus hydrothermal fluids, as suggested by several petrographic and geochemical evidence. The generation of mantled feldspars is probably related to isothermal decompression and magma mixing, which is compatible with the epsilon Nd-i signatures (-3.76 to -4.40). Based on this research, both processes have contributed to the petrogenesis of the studied porphyries.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 23