Abstract

SILVA-ARIAS, Alejandro et al. Basement characteristics in the lower magdalena valley and the sinú and san jacinto fold belts: evidence of a late cretaceous magmatic arc at the south of the colombian caribbean. C.T.F Cienc. Tecnol. Futuro [online]. 2016, vol.6, n.4, pp.5-36. ISSN 0122-5383.  https://doi.org/10.29047/01225383.01.

The onset of subduction in the Caribbean Plate under the South American Plate allowed the development of an Active Continental Margin; the age of onset, the mechanism and the plates involved are a discussion topic, especially at the Colombian South Caribbean Margin, due to the lack of geological information related to the basement. This article integrates petrographic, geochemical analyses and U/Pb dating of basement samples, in addition to the inclusion of published magnetic anomalies maps from the North of Colombia, in order to generate a compositional distribution map of the basement and determine the presence of a magmatic arc under the sediments of the Lower Magdalena Valley (LMV), which supports the existence of a Late Cretaceous active continental margin represented by a magmatic arc, called Magmatic Arc of Magangué. Dating of the arc yield a Late Cretaceous Age (84-74 Myr), and petrographic and geochemical evidence suggests it is comprised of igneous bodies of felsic to intermediate composition, which intrude the LMV continental crust, originated in a subduction setting. The origin of the LMV continental crust seems to be related to the continent-continent collision (consolidation of Pangaea) during the Permian (300 Ma ago), and to the post-Alleganian extension event of Triassic age (232 Ma ago).

Keywords : Magmatic Arc; U-Pb geochronology; subduction; Caribbean; South America.

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