IGCP Project short title: Caribbean Plate Tectonics Duration and ...

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In the panel discussions that followed the oral presentations, the main issues
centered on the origin of various critical geologic terranes in Cuba such as the Escambray,
Purial, and Grenvile metamorphic complexes, whether they are allochthonous or
autochthonous, and how they can be integrated into the geologic evolution of the northern
Caribbean plate boundary. For example, according to present knowledge, Purial massif is a
vulcano-plutonic "island arc" complex of Cretaceous age, which is characterized by high Plow
T metamorphism. Nevertheless, the present tectonic position of this complex can hardly
be associated with a subduction zone of any age. A lively discussion was also held on how
the Rosario belt of western Cuba and the Placetas belt in central Cuba relate to the
development of the ProtoCaribbean crust. Usually these belts have been interpreted as the
southern basin-ward deposits of the Bahamas platform, but another interpretation is that they
represent the sediments and crust of the ProtoCaribbean.
Concerning the tectonic position of the Cuban Cretaceous vulcano-plutonic island
arc suites, important unpublished information was presented to the audience, including highresolution
seismic profiles of several areas of Cuba. The issue was to evaluate if the island
arc suite is allochthonous above the Escambray, with the roots located south of the
Escambray; or if the island arc suite is allochthonous above the northern ophiolites and
Placetas-Rosario belts, then the Escambray is an allochthonous terrain located within the
north diping subduction zone of the arc. Seismic data favour the second possibility, but the
issue require more research.
After more than 5 hours of very often high-tuned discussions, many agree that there
are some areas (call them terrains, belts or masifs) which are yet too poorly known as to be
interpreted in a single easy manner, as it is currently assumed by some Caribbean plate
tectonic models. More field and laboratory research focused on the petrology and internal
structure of the Socorro (Grenvile), Escambray, Purial and Pinos metamorphic complexes, as
well as on the stratigraphy and tectonic position of the Placetas and Rosario belts is urgently
required before a fair interpretation of the origin of these geologic units can be reach.
Available P-t path studies, isotopic dating and geochemical data for the Escambray and
Purial are still insufficient. Fortunately, several attendees to the meeting already agreed to
work on some of these areas, and this is probably one of the most important results of the
panel workshop.
WORKSHOP ON THE GEOCHEMISTRY OF THE CARIBBEAN PLATEAU AND
CRETACEOUS ISLAND ARC TERRANES, AND THEIR IMPLICATIONS FOR THE
GEODYNAMICS OF THE CARIBBEAN
Leicester, U.K., April 23-24, 2001
Convener: P.M.E. Thompson
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