Presence of high-grade rocks in NW Venezuela of possible Grenvillian affinity
Published:January 01, 2009
Sebastián Grande, Franco Urbani, 2009. "Presence of high-grade rocks in NW Venezuela of possible Grenvillian affinity", The Origin and Evolution of the Caribbean Plate, K. H. James, M. A. Lorente, J. L. Pindell
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High-grade metamorphic rocks – marble, charnockite, meta-anorthosite, metapelite, clinopyroxenite and garnet amphibolite – have been found in northwestern Venezuela. They occur as: (a) xenoliths in the Oligo-Miocene lavas of Cerro Atravesado, Central Falcón; (b) possibly olistoliths in Nuezalito Formation, NW Portuguesa; (c) in Cerro El Guayabo, an elongated east–west oriented hill in the Nirgua Complex, Yaracuy; (d) rounded clasts of marble in the basal conglomerate of Casupal Formation, Falcón; (e) rounded clasts of anorthosite and sillimanite gneiss in a conglomerate of Matatere Formation, Lara; and (f) basement cores extracted from La Vela Gulf, Falcón. These high-grade rocks probably suffered...
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The Origin and Evolution of the Caribbean Plate
This book considers the geology between North and South America. It contributes to debate about the area's evolution, particularly that of the Caribbean. Prevailing understanding is that the Caribbean formed in the Pacific and was engulfed between the Americas as the latter drifted west. Accordingly, the Caribbean Plate comprises internal, Jurassic–Cretaceous oceanic rocks, thickened into a Cretaceous hotspot/plume plateau, with obducted ophiolites and Cretaceous–Palaeogene, subduction-related, intra-oceanic volcanic arc and metamorphosed arc/continental rocks exposed on its margins. An alternative interpretation is that the Caribbean evolved in place. It consists largely of continental crust, extended in the Triassic–Jurassic, which subsided below thick Jurassic–Cretaceous carbonate rocks and flood basalts, and Cenozoic carbonate and clastic rocks. After uplift of ‘oceanic’ and volcanic arc rocks onto (continental) margins, the interior foundered in the Middle Eocene. Papers range from regional overviews and discussions of Caribbean origins to aspects of local geology arranged in a circum-Caribbean tour and ending in the interior. They address tectonics, structure, geochronology, seismicity, igneous and metamorphic petrology, metamorphism, geochemistry, stratigraphy and palaeontology.