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IGCP Project No.433 - Caribbean Plate Tectonics Italian-Caribbean Working Group - Brief report of activities (2002) related to the project

By Giuseppe Giunta (leader), Luigi Beccaluva (co-leader), Daniela Cutrupia, Massimo Coltorti, Franca Siena, Carmela Vaccaro, Michele Marroni, Luca Pandolfi, Gianfranco Principi, Elisa Padoa, Ivan Aiello and Emanuele Lodolo

Abstract

The WG has worked on the tectonic history of the Caribbean Plate margins, from the Jurassic until middle Tertiary, in particular through the study of the ophiolitic units involved in that orogenic belts. In 2002, the group has carried out field work in Guatemala, Cuba, Hispaniola and Venezuela, with a structural and petrological target, in particular on the main ophiolitic units along several transect. In January 2002 was held the IGCP 433 Workshop and 2^ Italian-Latin American Geological Meeting in memory of Gabriel Dengo on The Motagua Suture-Zone in Guatemala. The routine-researches have been carried out in the geological laboratories of the Italian universities of Palermo, Ferrara, Pisa and Firenze. Future activities will focus on the detailed tectonic reconstruction (with at least 2 or 3 field trips) of the main sector of both the northern and southern plate’s margins, also in the aims of the final IGCP 433 (Caribbean plate) regional symposium at the International Geological Congress of Florence 2004 (chairmen: M.Iturralde and G. Giunta). The results on the geology and petrology of the ophiolitic complexes, deformed and dismembered along the Caribbean Plate margins, contribute to the debate on the origin and evolution of the Caribbean Plate. A “near Mid-America” original location of the Jurassic-Cretaceous Caribbean oceanic realm (proto-Caribbean phase) is suggested. Its crustal accretion can be initially referred to multiple spreading centres (LREE-depleted MORB, in Venezuela, Costa Rica, Cuba, Guatemala, Hispaniola), evolving, in the western portion of the proto-Caribbean domain, to a thickened oceanic plateau (REE-flat MORB locally associated with picrites, in Costa Rica, Hispaniola, Venezuela, Dutch and Venezuelan Islands). At the same time both the South and North American continental margins were affected by rifting and within-plate tholeiitic magmatism (Venezuela and Cuba). From the Early to Late Cretaceous (eo-Caribbean phases) one subcontinental subduction zone with melange formation (recorded only in Venezuela) and two main stages of intraoceanic subduction may be recognised: 1) a first NE- and SE-dipping sinking of unthickened proto-Caribbean lithosphere, recorded by deformed and HP/LT metamorphosed ophiolitic melanges and volcano-plutonic sequences with island-arc tholeiitic affinity (IAT) in Venezuela, calc-alkaline affinity (CA) in Cuba and both IAT and CA affinity in Guatemala and Puerto Rico; 2) a second intraoceanic subduction, with reverse polarity, responsible for the first tectonic settlement of the Caribbean margins, recorded by unmetamorphosed tonalitic intrusives, and related to the onset of the Aves-Lesser Antilles arc system and its eastward migration. In the Late Cretaceous, the inner and undeformed portions of the Caribbean Plate, i.e. the Colombian and Venezuelan Basins, were trapped by the intervening Pacific subduction, building the Central American Isthmus. The Tertiary to Present eastward displacement of the Caribbean Plate led to the progressive dismembering of the deformed ophiolitic belts and their involvement in its margins

Topics: Italian-Caribbean, Caribbean Plate margins, ophiolitic, orogenic belts
Publisher: CNR
Year: 2002
OAI identifier: oai:iris.unife.it:11392/1867515
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