Accreted oceanic terranes in Ecuador: Southern edge of the Caribbean Plate?
Etienne Jaillard, Henriette Lapierre, Martha Ordoñez, Jorge Toro Álava, Andrea Amórtegui, Jérémie Vanmelle, 2009. "Accreted oceanic terranes in Ecuador: Southern edge of the Caribbean Plate?", The Origin and Evolution of the Caribbean Plate, K. H. James, M. A. Lorente, J. L. Pindell
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The western part of Ecuador is made from several oceanic terranes, which comprise two oceanic plateaus, of Early (c. 120 Ma) and Late Cretaceous age (c. 90 Ma), respectively. The older oceanic plateau was accreted to the Andean margin in the Late Campanian (c. 75 Ma). Fragments of the Turonian–Coniacian plateau were accreted to the Ecuadorian margin in the Late Maastrichtian (c. 68 Ma, Guaranda terrane) and Late Paleocene (c. 58 Ma, Piñón–Naranjal terrane). The Guaranda terrane received either fine-grained oceanic sediments of Coniacian–Maastrichtian age, or island arc/back-arc volcanic suites of Middle Campanian–Middle Maastrichtian age. The Piñón–Naranjal terrane recorded a comparable history, completed in the Maastrichtian–Paleocene, either by pelagic cherts, or by island arc products (Macuchi arc). The Late Cretaceous plateau of Ecuador is interpreted as part of the Caribbean oceanic plateau (COP), because their evolutions are comparable. If so, the COP was not formed by the Galápagos hotspot, but on the Farallón oceanic plate, south of Ecuador and close to the South American margin. The COP belonged to the Farallón plate, until a subduction zone separated both plates in the Middle Campanian, giving way to a well-developed Mid Campanian–Mid Maastrichtian island arc. Accretion in the Late Maastrichtian triggered a change in the subduction system, and the development of a new arc system of Late Maastrichtian–Late Paleocene age, which crosscut the South America–COP plate boundary. The last accretion occurred in the Late Paleocene.
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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.