Geochronology of Proterozoic basement inliers in the Colombian Andes: tectonic history of remnants of a fragmented Grenville belt

Abstract

Basement inliers of high-grade metamorphic rocks within the eastern Colombian Andes record a Grenvillian history. Among them, the Garzón Complex and the Dibulla, Bucaramanga and Jojoncito gneisses were studied using different geochronological methods to produce better correlations in the context of the reconstruction of the Grenville belt and of the supercontinent of Rodinia. The dynamic evolution of all of these units includes a final collisional event with exhumation of high-grade rocks. Such a tectonic history bears strong similarities with the Grenville Province in Canada and seems to confirm that these domains took part in the aggregation of Rodinia. Mesoproterozoic U-Pb zircon ages indicate heritage from magmatic protoliths, and the Sm-Nd model ages, as well as the εNd values, suggest derivation from an evolved continental domain, such as the Amazonian craton, with some mixing with juvenile Neoproterozoic material. When these continental fragments are correlated with similar terrains in Mexico and the Central Andes, a large crustal fragment is implied; very probably it made up the southern portion of the Grenville belt within Rodinia, which was disrupted when Laurentia separated from Gondwana forming the Iapetus Ocean, leaving behind cratonic fragments that were later accreted to the South American Platform.

Laurentia-Baltica-Amazonia relations during Rodinia assembly

“…This event has been linked to collision between northern Amazonia and Baltica (Cardona et al, 2010;Ibanez-Mejia et al, 2011;Keppie et al, 2001;Keppie et al, 2004;Weber et al, 2010). Argon-argon ages in the range 970-920 Ma from the Colombian basement inliers are related to regional exhumation and cooling of the orogen (Cordani et al, 2005).…”

Ortoneises en la Franja Silos-Babega, Macizo de Santander, Colombia: evidencias de la orogenia famatiniana en los Andes del norte

“…El grado metamórfico de esta unidad corresponde a la zona de la sillimanita en facies anfibolita. El protolito de esta unidad se ha considerado Meso-Proterozoico, siendo el evento metamórfico de edad 1020 Ma (Cordani et al, 2005).…”

Occurrence and growth history of texturally sector- and sigmoidal-zoned garnet in the San Lo renzo Schists in the Sierra Nevada de Santa Marta massif (Co lombia)

“…Most of this province is covered by Jurassic volcanic rocks (Tschanz et al, 1974;Restrepo-Pace et al, 1997;Ordoñez et al, 2002;Cordani et al, 2005). The Province of Sevilla is bounded on the east by the Seville lineament and on the west by the Guachaca fault; it is composed of mylonitic granitoids and amphibole and micaschists of Paleozoic age (Tschanz et al, 1969(Tschanz et al, , 1974Cardona et al, 2006).…”