INVESTIGADORES
GALLI Claudia Ines
congresos y reuniones científicas
Título:
Geochemistry of interstitial brines of Guayatayoc Playa Lake, Northern Argentina Puna Plateau. Preliminary results
Autor/es:
LOPEZ STEINMETZ, R.L.; GALLI, C.I.; CHAYLE, W.
Lugar:
Córdoba
Reunión:
Congreso; 11th International Conference on Salt Lake Research; 2011
Institución organizadora:
International Society for Salt Lake Research
Resumen:
The Guayatayoc
playa lake is a 200 km² endorheic-evaporitic dry lake located at 3400 meters in
the northwestern part of the Argentinean Puna Plateau, between 23°11?S -
23°26?S and 65°57?W - 65°49?W. The region has BSK type weather and rainfalls
are generally less than 300 mm per year. The topographic depression of
Guayatayoc is bordered by structural ranges which define the well developed shaped
alluvial fans in both west and east margins. Playa lake surrounding major
lithologies include Ordovician basement marine
metasedimentary rocks, Jurassic-Cretaceous dioritic and granitic plutons,
Cretaceous-Paleogene sinrift and
post-rift marine calcareous sandstones and continental red beds and Miocene
dacitic and andesitic volcanic rocks with ignimbrite prevalence. The quaternary
filling sediments of the Guayatayoc playa lake are characterized by green clays
with ulexite cotton balls at half a meter deep. At the top, the surface holds a
thinner than 10 cm halite crust.
Interstitial
brines were sampled during the last dry season. Preliminary
results of chemical analysis are showing Na+ ? (K+) / CI-
? (SO4=) brine types developing in a neutral-sulfated pathway. Its
pH is 7.5, then only HCO3= represents alkalinity. Salinities are
approximately 117.8 psu (KCl) while maximum analytical content of Na,K,LiCl is
123 g/l. Major ion ratios founded were 1:7.8 for Na+/Cl-
and 1:9.4 for Ca2+/SO4=. An Ordovician rocks parental
link is assigned to B3+. Based on Guayatayoc brine ion concentration
ratios, Li+ and Mg2+ seems to have the same origin (Li/Mg
1:1.07) unlike other cations which appear to be unrelated: Li/K 1:168, Mg/K
1:157, B/K 1:46.7 and Li/B 1:3.6. Aeolian recycling salts seem to have some
influence in the Na+ and Cl- ion concentrations for some
of input waters coming from west margin.