Late Cretaceous–Paleocene metamorphic evolution of the Sierra Nevada de Santa Marta: Implications for Caribbean geodynamic evolution

A Late Cretaceous–Paleocene metamorphic event in the Santa Marta massif (northern Colombia) is characterized by a P–T path with a pressure increase after an initial temperature increase or temperature increasing simultaneously with pressure. In either case, this path indicates loading of pre-heated crust in agreement with the proposed models for the origin of the Caribbean plate and with the current configuration of the Caribbean–South America plate boundary. The P–T path constructed in a pelitic schist from the inner Santa Marta metamorphic belt indicates that garnet grew during a loading event that caused a pressure increase of up to 1.5 kbar in a subduction setting. Sample P–T path and Santa Marta massif tectonic features are compatible with metamorphism on an accretionary wedge with heating prior to loading or synchronous loading and thermal relaxation during thickening of the wedge, this could result from a sedimentary pile accumulated in an anomalously hot oceanic crust. P–T path is also compatible with low angle subduction similar to the current configuration of the subduction of the Caribbean plate below the South America plate and to extensive retrograde metamorphism most likely related to exhumation.

► We construct a P–T path in a pelitic schist from the Sierra Nevada de Santa Marta.
► P–T path characterizes Late Cretaceous–Paleocene metamorphism in the massif.
► P–T path signature indicates loading of a pre-heated crust.
► Result is in agreement with the two current models of Caribbean plate evolution.