ISOTOPIC FEATURES FOR THE GEOTHERMAL AQUIFER OF DECEPTION ISLAND, SOUTH SHETLAND, ANTARCTICA

PARICA, C A,; REMESAL, M. B.; SALANI, F. M.

Heidelberg

Otro; 22nd International Collquium on Latein Amerikan Earth Sciences; 2011

Ruprecht-Karls-Universität Heidelberg

Deception Island is an active volcano in the Bransfield Strait sited in a marginal basin between the Antarctic Peninsula and the South Shetland Islands. Several ages had been proposed for its origin, based just on the stratigraphy 5 Ma, on palaeomagnetic studies by Valencio et al. (1979) the age is related to the Bruhnes cycle, which means 780.000 years. Keller et al. (1991) on K/Ar ages presented an age of 153.000 ± 46 years. Evolutive studies based on isotopes were developed by Parica et al. (1990), Ortíz Ramis, et al. (1987). For a better interpretation of the geothermal aquifer, several streams, fumaroles, sea water, snow and ice, and glassy rocks were sampled for different isotopic analyses, 18O, 2H and 87Sr/86Sr. The interaction in the volcanic system is clear, access of sea water to the geothermal aquifer, also fresh water in lesser proportions. Everything has the isotopic signature to understand the interaction. The glassy rocks, also are representative of the presence of sea water in the geothermal aquifer, when the glass is dry has 87Sr/86Sr typical for these rocks and origin (0.7031 and 0.7032), but in hydrated glasses the 87Sr/86Sr ratios the sea water signature were recognized (0.7093). Some others chemistry (Cl-) and isotopic analysis by Dapeña et al. (2005) were also useful to understand the dynamic of this volcano.