C, O, Sr isotope and rare earth elements (REE) study in sedimentary cretaceous rocks from the east cordillera (Dpto. de Santander, Colombia): Paleohydrogeological implications

The study of calcareous materials (from rocks and veins) of the cretaceous Rosablanca, Paja and Tablazo formations outcropping to the south of the Department Santander allowed the distinction of two carbonates groups on the basis of their isotopic (δ18 O y (δ13C) signature: a) carbonates type 1: with a range of (δ18O values between 20.15% and 22.28% and relativity homogeneous (δ13C values 1-1% < (δ13C<0.9%; b) carbonates type II: with (δ18O values between 20.31% and 21.60%, and 1.8% < (δ13C < 5.8% values. Some differences in the isotopic signature of calcareous rocks and veins could indicate the influence of aloctonous waters. geochemical data analysis of REE of the cretaceous Paja and Rosablanca formations, prove the marine features of these two units, as indicated by the negative Eu and Ce anomalies. The absence of a negative anomaly in Eu of the K-mica aggregates from veins is the result of the oxic conditions at the time of the hydrothermal event. The Sr geochemistry (87sr l86sr) in the studied samples indicates a mixed source derived from both: continental and marine. On the other hand, the Sr of circulating waters through fractured rocks; show that it was derived exclusively from theses host rocks