Geochemistry and Geochronology of the Guajira Eclogites, northern Colombia : evidence of a metamorphosed primitive Cretaceous Caribbean Island-arc
Weber, M. (Universidad Nacional de Colombia)
Cardona, A. (Smithsonian Tropical Research Institute)
Valencia, V. (The University of Arizona. Department of Geosciences)
Altenberger, U. (Potsdam Universität)
López-Martínez, M. (Centro de Investigación Científica y de Educación Superior de Ensenada (Mèxic). Departamento de Geología)
Tobón, M. (Universidad Nacional de Colombia)
Zapata, S. (Universidad Nacional de Colombia)
Zapata, G. (Universidad Nacional de Colombia)
Concha, A. E. (Universidad Nacional de Colombia)

Date:	2011
Abstract:	The chemical composition of eclogites, found as boulders in a Tertiary conglomerate from the Guajira Peninsula, Colombia suggests that these rocks are mainly metamorphosed basaltic andesites. They are depleted in LILE elements compared to MORB, have a negative Nb-anomaly and flat to enriched REE patterns, suggesting that their protoliths evolved in a subduction related tectonic setting. They show island-arc affinities and are similar to primitive islandarc rocks described in the Caribbean. The geochemical characteristics are comparable to low-grade greenschists from the nearby Etpana Terrane, which are interpreted as part of a Cretaceous intra-oceanic arc. These data support evidence that the eclogites and the Etpana terrane rocks formed from the same volcano-sedimentary sequence. Part of this sequence was accreted onto the margin and another was incorporated into the subduction channel and metamorphosed at eclogite facies conditions. 40Ar-39Ar ages of 79. 2±1. 1Ma and 82. 2±2. 5Ma determined on white micas, separated from two eclogite samples, are interpreted to be related to the cooling of the main metamorphic event. The formation of a common volcano-sedimentary protolith and subsequent metamorphism of these units record the ongoing Late Cretaceous continental subduction of the South American margin within the Caribbean intra-oceanic arc subduction zone. This gave way to an arc-continent collision between the Caribbean and the South American plates, where this sequence was exhumed after the Campanian.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Eclogites ; Primitive island-arc ; Geochronology ; Guajira Peninsula ; Colombia ; Caribbean
Published in:	Geologica acta, Vol. 9, Núm. 3-4 (setembre-desembre 2011) , p. 425-443, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/247930
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001740
DOI: 10.1344/105.000001740

20 p, 4.4 MB

The record appears in these collections:
Articles > Published articles > Geologica acta
Articles > Research articles