Study of fluids related to hydrothermal alteration of biotite granites from Gerês and Guarda (Portugal) [Estudo dos fluidos associados com a epissienitização de granitos biotíticos do Gerês e da Guarda (Portugal)]

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Jaques, L (Author) Other; Bobos, I (Author) FCUP; Noronha, F (Author) FCUP

Journal

Title: Comunicações Geológicas

Vol. 97

Pages: 81-98

ISSN: 0873-948X

Publisher: LNEG - Laboratório Nacional de Energia e Geologia

Indexing

ISI Web of Knowledge

Scopus - 6 Citations

Other information

Authenticus ID: P-008-E7X

Abstract (EN): In granites, particularly from Gerês and Guarda regions, occur reddish altered rocks, commonly known as "episyenites". These rocks resulted from a hydrothermal alteration process and involved alkali metasomatism, magmatic quartz dissolution and transformation of the primary minerals present in granites. The hydrothermal fluids, directly associated with the episyenitization process, were trapped in quartz microfractures - Fluid Inclusion Planes (FIP), consistent with the most important directions of altered structures. These fluids are low-salinity aqueous fluids from the H2O-NaCl system and homogenization temperatures lower than 300 °C. They have an alkaline character, possibly with a meteoric origin and circulated to a depth lower than 5 km during the final events of the Hercynian orogeny. © INETI 2010.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 18