C, O, Sr ISOTOPE AND RARE EARTH ELEMENTS (REE) STUDY IN SEDIMENTARY CRETACEOUSROCKS FROM THE EAST CORDILLERA (DPTO. DE SANTANDER, COLOMBIA):PALEOHYDROGEOLOGICAL IMPLICATIONS
Published 2013-07-18
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Abstract
The study of calcareous materials (from rocks and veins) of the Cretaceous Rosablanca, Paja and Tablazo Formationsoutcropping to the South of the Dpto. Santander allowed the distinction of two carbonates groups on the basis of theirisotopic (δ18O y δ13C) signature: a) Carbonates type I: with a range of δ18O values between 20.15‰ and 22.28‰ and relativityhomogeneous δ13C values -1.1‰<δ13C<0.9‰; b) Carbonates type II: with δ18O values between 20.31‰ and 21.60‰, and1.8‰ <δ13C< 5.8‰ values. Some differences in the isotopic signature of calcareous rocks and veins could indicate theinfluence of aloctonous waters. Geochemical data analysis of REE of the Cretaceous Paja and Rosablanca Formations, provethe marine features of these two units, as indicated by the negative Eu and Ce anomalies. The absence of a negative anomalyin Eu of the K-mica agregates from veins, is the result of the oxic conditions at the time of the hydrothermal event. The Srgeochemistry (87Sr/86Sr) in the studied samples, indicates a mixed source derived from both: continental and marine. On theother hand, the Sr of circulating waters through fractured rocks, show that it was derived exclusively from theses host rocks.
Key words: Departamento de Santander, carbonates, stable isotopes, fluids, REE and Sr geochemistry.
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References
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