Tectonomagmatic setting and provenance of the Santa Marta Schists,northern Colombia: Insights on the growth and approach of Cretaceous Caribbean oceanic terranes to the South American continent |
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| Institution: | 1. Departamento de Procesos y Energía, Facultad de Minas, Universidad Nacional de Colombia, Medellín, Colombia;2. Grupo de Investigación en Geología y Geofísica (EGEO), Universidad Nacional de Colombia, Medellín, Colombia;3. Smithsonian Tropical Research Institute, Balboa, Ancon, Panama;4. Departamento de Materiales y Minerales, Facultad de Minas, Universidad de Colombia, Medellín, Colombia;5. Departamento de Física y Geociencias, Universidad del Norte, Barranquilla, Colombia;6. School of the Environment, Washington State University, Pullman, WA, USA;7. Departamento de Ciencias de la Tierra, Universidad EAFIT, Medellín, Colombia;8. Instituto de Geociências, Universidade de São Paulo, São Paulo, Brazil;1. Department of Earth and Environmental Sciences, University of Geneva, Rue des Maraichers 13, 1205 Geneva, Switzerland;2. Institute of Mineralogy and Geochemistry, University of Lausanne, 1015 Lausanne, Switzerland;3. Instituto Colombiano del Petróleo, Ecopetrol, Bucaramanga, Colombia;2. CRU, London, United Kingdom;3. Departamento de Geología, Facultad de Ingeniería en Geología y Petróleos, Escuela Politécnica Nacional, Quito, Ecuador;4. Norway Geological Survey, Trondheim, Norway;5. School of Geosciences, The University of Edinburgh, Edinburgh, Scotland;6. Geological Institute, ETH Zürich, Zürich, Switzerland |
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| Abstract: | Metamorphosed volcano-sedimentary rocks accreted to the northern South American continental margin are major vestiges of the Caribbean oceanic plate evolution and its interactions with the continent. Selected whole rock geochemistry, Nd–Sr isotopes and detrital zircon geochronology were obtained in metabasic and metasedimentary rocks from the Santa Marta and San Lorenzo Schists in northernmost Colombia. Trace element patterns are characterized by primitive island arc and MORB signatures. Similarly initial 87Sr/86Sr-εNd isotopic relations correlate with oceanic arcs and MORB reservoirs, suggesting that the protoliths were formed within a back-arc setting or at the transition between the inta-oceanic arc and the Caribbean oceanic crust. Trace element trends from associated metasedimentary rocks show that the provenance was controlled by a volcanic arc and a sialic continental domain, whereas detrital U/Pb zircons from the Santa Marta Schists and adjacent southeastern metamorphic units show Late Cretaceous and older Mesozoic, Late Paleozoic and Mesoproterozoic sources. Comparison with continental inland basins suggests that this arc-basin is allocthonous to its current position, and was still active by ca. 82 Ma. The geological features are comparable to other arc remnants found in northeastern Colombia and the Netherland Antilles. The geochemical and U/Pb detrital signatures from the metasedimentary rocks suggest that this tectonic domain was already in proximity to the continental margin, in a configuration similar to the modern Antilles or the Kermadec arc in the Pacific. The older continental detritus were derived from the ongoing Andean uplift feeding the intra-oceanic tectonic environment. Cross-cutting relations with granitoids and metamorphic ages suggest that metamorphism was completed by ca. 65 Ma. |
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