- 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 island-arc 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. Ar-40-Ar-39 ages of 79.2 +/- 1.1Ma and 82.2 +/- 2.5Ma determined on white micas, separated from twoThe 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 island-arc 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. Ar-40-Ar-39 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.…
MetadatenVerfasserangaben: | Marion Weber, A. Cardona, V. Valencia, Uwe AltenbergerORCiDGND, M. Lopez-Martinez, M. Tobon, Sebastian Henao ZapataORCiDGND, G. Zapata, A. E. Concha |
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DOI: | https://doi.org/10.1344/105.000001740 |
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ISSN: | 1695-6133 |
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Titel des übergeordneten Werks (Englisch): | Geologica acta |
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Verlag: | Facultat de Geologia, Divisio III, Ciències Experimentals i Matemàtiques, Universitat de Barcelona |
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Verlagsort: | Barcelona |
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Publikationstyp: | Wissenschaftlicher Artikel |
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Sprache: | Englisch |
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Jahr der Erstveröffentlichung: | 2011 |
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Erscheinungsjahr: | 2011 |
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Datum der Freischaltung: | 26.03.2017 |
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Freies Schlagwort / Tag: | Caribbean; Colombia; Eclogites; Geochronology; Guajira Peninsula; Primitive island-arc |
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Band: | 9 |
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Ausgabe: | 3-4 |
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Seitenanzahl: | 19 |
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Erste Seite: | 425 |
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Letzte Seite: | 443 |
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Fördernde Institution: | Universidad Nacional de Colombia through DIME [30805975] |
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Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
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Peer Review: | Referiert |
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Publikationsweg: | Open Access |
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