THE USE OF RAMAN MICROSPECTROMETRY FOR FLUID INCLUSION CHARACTERISATION IN A Li-PEGMATITE FROM COVAS DO BARROSO AREA, NORTHERN PORTUGAL

摘要

Aiming to characterise the P-T-X conditions of the fluids associated with Li-mineralisations inBarroso-Alvão, fluid inclusion studies were carried out in a pegmatite vein from the “BarrosoMine”, Covas do Barroso.The Barroso-Alvão aplite-pegmatite field comprises several lithium-rich veins with spodumeneand/or petalite mineralisation, hosted by metasediments of upper Ordovician to lower Devonianage, which have been regionally metamorphosed to the andalusite zone. Hercynian granites alsooccur in the region, namely syntectonic two-mica granites and post-tectonic biotite granites.Micro-thermometric studies were conducted in selected fluid inclusions in quartz (clear quartz andmilky quartz) and spodumene from a representative sample of the Li-pegmatite vein, usingChaixmeca and Linkam PR600 stages on a Nikon microscope. The Raman analysis of the volatilespecies and solids present in the fluid inclusions was performed using a Horiba Jobin-YvonLabRam (632.8 nm, He-Ne laser), according to procedures and calibration described by Prieto etal. .