Caribbean Plate Tectonics Site
Caribbean Meetings and Field Trips
By Andrés Pérez-Estaún, Antonio García-Casco and Yamirka Rojas-Agramonte (Conveners)
Dear colleagues,
A small part of the Caribbean community met in Vienna on Thursday 6th April at the General Assembly of the European Geosciences Union (EGU). The purpose of this report is to briefly describe the scientific results presented and progress made at the session “Composition, structure and evolution of the Caribbean lithosphere and surrounding areas”. To start with the meeting, it was introduced to the audience the current issue of Geologica Acta which represents the Final Memoir of the UNESCO/IUGS IGCP Project 433 (Caribbean Plate Tectonics), dedicated to the “Stratigraphic, Magmatic, Metamorphic and Tectonic Events; and its plate tectonic implications” available for free download at:
http://www.geologica-acta.com:8080/geoacta/HomeAC.do)
The session, which was attended by geoscientists from different countries and field of interest, included six oral presentations and five posters whose abstracts are available at:
http://www.cosis.net/members/meetings/sessions/accepted_contributions.php?p_id=193&s_id=3430.
Most presentations provided new petrologic, geochemical and geochronological data, new ideas and evaluations of existing models for the evolution of the Caribbean plate with emphasis on Cuba and Hispaniola.
Manuel Iturralde-Vinent (from Cuba) opened the session summarizing some of the main conclusion of the recently finished IUGS/UNESCO IGCP Project 433. Manuel then proceeded by debating the two main group of models for the origin of the Caribbean Plate, namely the in-situ and the allochthonous models. He indicated that present geological knowledge is best explained by allochthonous models, but emphasized that further effort is needed to integrate new paleontologic, stratigraphic and magmatic data that not exactly fit into this type of model.
New petrological data from the ophiolite mélange in Cuba was presented by Antonio García-Casco (from Spain), including a series of cross sections for eastern Cuba to explain the contrasted P-T evolution of high-pressure metamorphic complexes of this region in Cretaceous time. Antonio’s interpretation suggests the existence of two subduction zones in the late Cretaceous. Also referring to eastern Cuba, Claudio Marchesi (from Italy) presented new geochronological and geochemical data for the Cretaceous arc rocks within the ophiolites and El Purial Mountains. He described three different igneous suites for these volcanic rocks which now appear juxtaposed and display complex field relations.
Martin Meschede (from Germany) presented a geodynamic model for Cuba based on geological information and satellite image interpretation. Martin´s view represents a sort of authocthonous model for the formation of the Caribbean. Yamirka Rojas-Agramonte (from Cuba) reported new U-Pb SRHIMP zircon ages for several sedimentary, magmatic and metamorphic rocks of Cuba. Detrital zircons from Jurassic sediments in eastern Cuba yield surprisingly old ages (even Archaean) suggesting a South American (Guyana craton) provenance. Other old Paleozoic zircons were recovered, which add to the already complex history of formation of the Caribbean.
Javier Escuder-Viruete (from Spain) presented two contributions dealing with the petrology and geochemistry of eastern Hispaniola. New data for Samaná Peninsula complex suggest cooling due to exhumation in the late Eocene-early Oligocene for rocks of the Punta Balandra unit, as a result of the initial oblique collision of the Bahamas Platform with the Caribbean arc. On the other hand, Javier reported new data from the Los Ranchos Formation (equivalent to the Water Island, Los Pasos and pre-Robles formations in Virgin Islands, Cuba, and Puerto Rico) and interpreted the boninites and depleted IAT rocks from the lower unit to have formed during subduction initiation.
John Lewis (from USA) presented a comparison between two peridotite occurrences in Puerto Rico and the Dominican Republic, suggesting that at least two Jurassic-Cretaceous mantle sections existed within the northern Caribbean plate margin; one representing mid-oceanic accretion (Monte del Estado, PR) and the other reflecting subduction-mantle plume interaction (Loma Caribe, DR).
Ricardo Valls (from Cuba-Canada) presented the result of over three years of field exploration in Guatemala, showing a field guide to nickel-bearing laterites.
During the poster sessions there were active and interesting debates, and people with various interests show up to exchange ideas and make plans for future cooperative research. In this aspect the session was very useful, as new project proposal were discussed in order to investigate some of the problematic issues of the still insufficiently understood Caribbean region.
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Dr. Yamirka Rojas-Agramonte
Institut für Geowissenschaften,
Johannes Gutenberg-Universität,
Becherweg 21 D-55099 Mainz,
Germany
Tel.+49 6131 3922164
Fax +49 6131 3924769
email: rojas@uni-mainz.de
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