Sedimentary signatures in Jambaló Blueschist : Tectonic implications

Abstract

The aim of this contribution is to analyze the sedimentary influence on the protoliths that gave rise to the blue schists of Jambaló, Cauca, Colombia, through the detailed identification of their mineralogical and structural characteristics. The hypothesis posits that the protolith of the Jambaló blue schists exhibits significant signs of a sedimentary component, which may reflect the proximity of an oceanic arc to the western margin of South America during the Cretaceous period. Fieldwork and petrographic analyses were conducted to characterize the blue and green schists in the area. Previous geochemical data were also reanalyzed. The results indicate that both types of schists share a common origin but followed distinct metamorphic paths. Geochemistry suggests a mixture of pelagic and terrigenous sediments in the protoliths, with a higher proportion of pelagic sediments. This supports the hypothesis of the proximity of an oceanic arc that accumulated these sediments. In conclusion, the Jambaló blue schists represent a metamorphic belt distinct from those previously proposed for the region. Their protoliths reflect the approach of an intra-oceanic arc to the continental margin during the Cretaceous.