C. Delascuevas et Jj. Pueyo, THE INFLUENCE OF MINERALOGY AND TEXTURE IN THE WATER-CONTENT OF ROCK-SALT FORMATIONS - ITS IMPLICATION IN RADIOACTIVE-WASTE DISPOSAL, Applied geochemistry, 10(3), 1995, pp. 317-327
The consideration of the use of salt formations as possible radioactiv
e waste disposal sites led us to attempt to determine the extent to wh
ich their brine content could influence the performance of the disposa
l system. Bedded rock salt from the Cardona, Zaragoza and Guendulain F
ms., as well as diapiric rock salt from northern and southeastern Spai
n, have been selected and their water contents characterized by thermo
gravimetry. Free water content (intergranular water and water in fluid
inclusions) in the studied formations ranges from 0.01 to 1.24% weigh
t. In addition, the presence of hydrated minerals increases the amount
of total water in the rock (up to 3.50%). Clear differences between t
he studied formations are observed in the total amount of water and in
the form of water entrapment in rock salt. The results obtained have
allowed the classification of the studied rock salt formations with re
spect to their free-brine content as water-poor (around 0.1% in averag
e), intermediate water-rich (around 0.2%) and water-rich (higher than
0.3%). The petrographical features of the rock salt, such as mineralog
ical content and halitic textures, play an important role in its water
content. Whilst brine in fluid inclusions is related to the halite te
xture, intergranular brine depends mainly on the content of clay and s
ulphate minerals.