Descripció:
Fluid inclusions in quartz and scheelite from two localities of a vein
field have been studied. The veins are related to a latehercynian granitic
intrusion. The ore minerals from the veins are arsenopyrite, pyrite, pyrrhotite,
chalcopyrite, gold and sulphosalts of the PbS-Bi z-S,-Sb2S 3 system.
Two kinds of fluid inclusions have been found in both localities: a biphasic
type and a CO2 rich triphasic type. Homogeneization temperatures of
the first type inclusions are around +150 °C in the locality nearer to the
intrusion, and around +200 °C in the other one. Therefore, zonation of
the temperatures with regard to the granitic outcrop is inverted.
Studies in the chemistry of the mineralizing solutions have been also
carried out. The homogeneity in the type of inclusions can be followed
in both localities, by means of similar salinities, and it is around 17 % weight
NaCI for biphasic inclusions. In these inclusions the presence of CaC12
in the solutions is showed by a drecrease of euthectic temperatures from
the theoretical —21 °C in the pure NaCI-H20 system. The amount of Ca02
is variable, but higher in inclusions found in the scheelite compared to coexisting
quartz. The CO2 liquid density is also very variable even in adjacent
inclusions from the same specimen, but is comparatively higher in veins
from localities far away from the intrusion, where the wall rock is calcareous.