Caribbean Plate Origin Meetings Reports

UNESCO/IUGS IGCP PROJECT 433 Caribbean Plate Tectonics

^*The information in this report will also be used for publication in 'Geological Correlation' (please feel free to attach any additional information you may consider relevant to the assessment of your project).

IGCP Project short title: Caribbean Plate Tectonics

Duration and status: On going (2000-2004)

Project leader(s):

1. Name: Manuel A. Iturralde-Vinent
   Address: Museo Nacional de Historia Natural
   Obispo no. 61, Plaza de Armas, La Habana 10100, Cuba.
   Tel.: (537) 63 25 89
   Fax: (537) 62 03 53
   e-mail: iturralde@mnhnc.inf.cu

2. Name: Edward G. Lidiak
   Address: Department of Geology and Planetary Science
   University of Pittsburgh, Pittsburgh, Pa., U. S. A.
   Tel: (412) 624-8871
   Fax: (412) 624-3914
   e-mail: egl+@pitt.edu

Date of submission of report: October 2001

Signature of project leader:

Summary of major past achievements of the project

2. Achievements of the project this year
     2.1. List of countries involved in the project
     2.2. General scientific achievements (including societal benefits)
     2.3. List of meetings with approximate attendance and number of countries
     2.4. Educational, training or capacity building activities
     2.5. Participation of scientists from developing countries
     2.6. Publications
           Abstracts and Presentations
           Papers
           Memoirs, Proceedings, and Guidebooks
           Open File Report
           Web Page Presentations
     2.7. Activities involving other IGCP projects or the IUGS

3. Activities planned
     3.1. General goals.
     3.2. Specific meetings and field trips

4. Project funding requested

5. Request for extension, on-extended-term-status, or intention to propose successor project

6. Attach any information you may consider relevant
     6.1 Internal Organization - Working groups and Networking
     6.1 Scientific Meetings and Workshop Reports
          IGC - Caribbean Plate Tectonics, Origin and Evolution
          17 Symposium on the Geology of Latin America
          4th Cuban Geological & Mining Congress, Workshop on the Northern Caribbean Plate Boundary
          Workshop on the Geochemistry of the Caribbean Plateau and Cretaceous Island Arc Terranes
          4th North American paleontological Convention - Caribbean Mesozoic Biogeography
          GSA Annual Meeting, Nov. 5-8, 2001

References Cited

Summary of major past achievements of the project

As this is our first bi-annual report for the years 2000-2001: the achievements embrace both years.
During these two years some important results are already evident as a consequence of focused discussion and selected presentations during the workshops and meetings. This approach has highlighted many problems that are currently among topics of research:

Origin of the Present-day Caribbean Plate. The concept that the present-day Caribbean Plate is allochthonous from the Pacific produce models that explain many aspects of the evolution of the Caribbean. Some advocates of the autochthonous models have reconsidered their points during the meetings in Stuttgart and Leicester. However, the allochthonous models still present major problems pending adequate solution.

The Galapagos hotspot and Caribbean plateau. There are two fundamental points of view regarding the role of the Galapagos hotspot in the geology of the Caribbean, which were the subject of extensive debate in Stuttgart and Leicester. One group holds that the Galapagos hotspot has nothing to do with the ProtoCaribbean crust or the Caribbean Plateau basalts, because the hot spot was always positioned west of both of them, and, consequently, was not the source of the so-called Caribbean plateau basalts. The other interpretation holds that the Galapagos hotspot actually produced the Caribbean plateau basalts and the ridges within the Nazca and Cocos plates. Pindell’s new unpublished palinispastic reconstructions say that it is impossible that the Galapagos hotspot produced the Caribbean plateau basalts. Trace element and isotopic geochemistry, however, do not rule it out (Hauff et al., 2000).

Subduction reversal in the Caribbean. The polarity of subduction of the Caribbean plate in Cretaceous time has been an intriguing topic since Mattson (1979) proposed that a reversal in subduction direction occurred during plate development. A summary of the evidence relevant to a reversal and the possible timing of the event is given by Jolly et al (1998). Most models seemingly require a change in subduction direction. For example, Pindell (1994, 2001) proposed a flip in the polarity of the arc at about 120 Ma. However, several researchers consider that the arc’s subduction flip required by Pindell’s model about 120 Ma ago is problematic for several reasons. Those investigating the origin of the plateau basalts disagree because a thick buoyant oceanic plateau would be very difficult to subduct, and would therefore significantly affect the subduction polarity reversal. They cite the arrival of the buoyant and thick Caribbean plateau at the eastward dipping subduction zone as a mechanism for the flip, in a situation analagous to that seen in the Solomon Islands with the attempted subduction of the Ontong Java oceanic plateau. However, Pindell’s latest unpublished model suggests that the 120 Ma polarity reversal occurred before the bulk of the plateau was formed, on the basis of the following pieces of evidence:

a. Abundant evidence for a large tectonic event around that time.
b. Unconformities in many arc-related sequences at ca. 120 Ma.
c. P-T paths from high-pressure metamorphic rocks.
d. Change in geochemical character from PIA to CA in many circum-Caribbean arcs.
e. The earlier the flip occurred, the easier would occur tectonically. At 120 Ma, the arc would have been short and straight and there was a powerful potential mechanism available (the acceleration of the opening of the Atlantic. At 75 Ma, the arc was ~2000km in length, and may have been very highly arcuate in shape, which would require huge internal deformation as the convex side changes from the SW to the SE. However, in the discussion at Leicester it was conceded that there is growing evidence for an earlier [and possibly more voluminous (Diebold et al., 1999)] pulse of plateau magmatism around 130-120 Ma. If that is the case, an earlier plateau could have formed and caused the postulated subduction flip, and the later plateau building events (78, 90 Ma) could have represented the last pulses of magmatism. Other authors also disagree with the subduction reversal because this flip does not explain the geochemical evolution of the Cretaceous arc magmatism in Cuba (Iturralde-Vinent, 1994, 1998; Kerr et al., 1999), neither the tectonics of north central Cuba (Iturralde-Vinent, 1994, 1998). Iturralde-Vinent (op.cit.) postulated a major change in the geometry of the convergent plate boundary between latest Campanian and Paleocene, involving deformation and almost complete extinction of arc volcanism, modification of the trend of the arc axis, and a major change in the orientation and geochemistry of the arc.

Alleged Albian-Campanian arc in Central America. Another subject that did not find agreement is the existence of an active Albian-Campanian island arc in Central America, and its evidence in the Nicoya Complex. According to a paper by Calvo and Bolt (1994), there is an arc-derived volcaniclastic calcalkaline section in Costa Rica, but several other attendees at the Stuttgart meeting (K. Hoernle, A. Astorga) stated that their geochemical and geological investigations in the Nicoya Complex do not confirm its presence. An Albian-Campanian island arc as part of present-day southern Central America is a major issue concerning the geology of the Caribbean plate, because the presence of a Central American mid-Cretaceous arc will reduce the rate of relative eastward movement of the Caribbean plate respect to North and South America, and would have a strong bearing on the palinspastic reconstruction of the circum-Caribbean fold-belts.

Tectonic position of the Cuban Southwestern terrains (CSWT). Many early plate tectonic models of the Caribbean ignored the CSWT, but fortunately, they have been taken into account in more recent versions (Lawver et al., 1999). However, as demonstrated by the lively discussion at the Havana meeting in March 2001, the geology of the CSWT is still too poorly known to be interpreted without ambiguity. More field and laboratory research focused on the petrology and internal structure of the Socorro (Grenvile), Escambray, Purial and Pinos metamorphic terrains, as well as on the stratigraphy and tectonic position of the Placetas and Rosario belts (terrains) are urgently required before a fair interpretation of the origin of these geologic units can be reached. Available P-t path studies, isotopic dating and geochemical data for the Escambray and Purial are still insufficient.

The Great Arc vs Multiple Arc concept. Pindell’s Caribbean models show a single "Great Arc" evolving from Cretaceous to recent as the leading edge of the Caribbean plate progressively occupy the space created by the separation of North and South America (Pindell, 1994; Mann, 1999). Another concept is that there were multiple arcs that evolved step by step from Cretaceous to Recent (Iturralde-Vinent, 1994, 1998, WebPage Forum). The Multi Arc concept evolves from the following ideas:

a. The occurrence of several magmatic and stratigraphic gaps within the Greater Antilles- Lesser Antilles volcano-sedimentary sections and the presence of unconformities at different time intervals on the various islands.
b. Modification of the geochemistry of the arc magmatism after some of these gaps, especially in Cuba (Iturralde-Vinent, 1994, 1998). However this does not apply to all of the tectonic breaks in Puerto Rico (Jolly et al , 1998}.
c. Modification of the orientation and geographic distribution of the arc magmatic axis after each gap, but specially after the earliest Cretaceous boninite and IAT arc, and after the Cretaceous arc (Kyzar, G., 2001: PhD Thesis: The George Washington University).

The Geometry of the Arcs. During the meetings in Rio de Janeiro, Stuttgart, and Cuba the geometry of the arc was the subject of consideration. A debate arose concerning the characteristics of the Greater Antilles- Aves Ridge- Lesser Antilles Cretaceous-Paleogene volcano-sedimentary complexes and the fact that the components of the original arcs (backarc, axial arc, front arc, subduction suture) are not evident in any cross-section of the present-day islands. The issue is that the arcs have been deformed by combined thrusting, extension along the axis, and were subsequently subdivided into distinct terrains that were the subject of rotation and eastward transportation. Consequently, the original geometry of the arcs are no longer represented by today’s outcrops and their elements can only be found along specific islands of the chain.

Polarity of the Paleogene Sierra Maestra-Cayman arc. Pindell (1994, 2001), Mann (1999) and other Caribbean plate tectonic modelers hold the position that the subduction zone of the Paleogene arc was located north of the arc and with a dip to the south. Another group (Iturralde-Vinent, 1994, 1998, Sigurdson et al., 1997) presented evidence that the Paleogene subduction zone dipped north and was located south of arc. Recent geochemical, geochronological and paleontological research in the area by G. Kyzar favor the subduction from the south model and the fact that the Paleogene arc developed after a Maastrichtian gap in the magmatic activity and with a distinct orientation with respect to Cretaceous volcanism (to be presented in GSA meeting in Boston, 2001). (Kyzar, G. (2001) PhD Thesis: The George Washington University).

2. Achievements of the project this year

2.1. List of countries involved in the project (*indicate the countries active this year)
   *Cuba, *Dominican Republic, *Puerto Rico, *Jamaica, *Trinidad & Tobago, *Grenada, *USA, *Canada, *Mexico, Guatemala, *Costa Rica, *Brazil, *Colombia, *Venezuela, *Chile, *Argentine, *Italy, *France, *Spain, *New Zealand, *United Kingdom, *Japan, *Germany.

2.2. General scientific achievements (including societal benefits)
The main scientific achievements of the project have been fully described above, so it is not necessary to discuss them again. Generally it can be stated that the goals of the project are being fulfilled, as we have been able to put together scientists from many different geographic areas to discuss the Caribbean models and the data that support the various interpretations. A field trip to important localities not recently visited before in Central Cuba was also a great success. Communication among Caribbean scientist have been enhanced through an electronic network provided by the project. These results are tightening and constraining the variables necessary to building viable Caribbean plate tectonic models, and to improving and understanding the area. This benefit will certainly enhance the possibility of forecasting geohazards in the area.

2.3. List of meetings with approximate attendance and number of countries.
The first meeting of the project in Río de Janeiro during the 31st International Geological Congress, General Symposium 17.6: Caribbean Plate Tectonics, Origin and Evolution (August 7-8th, 2000). It was attended by project members from Cuba, USA, Canada, Italy, Germany, United Kingdom, France, Venezuela, Argentina, etc). Four special oral presentations and 12 posters were the subject of interesting debates and active exchange of data and interpretations. The oral session was attended by 50 persons.

The second meeting in Stuttgart (October 11-13th, 2000) was organized as part of the 17 Coloquin on Latin American Geology, attended by nearly 300 scientists from countries in South America (Argentina, Brazil, Chile, Venezuela, Colombia), Central America (Costa Rica, Mexico), North America (USA), Europe (Italy, France, Germany, United Kingdom, etc.) and Cuba. Presented were 12 talks and 13 posters about the geology, paleontology and plate tectonics of the Caribbean, and a round table was organized to discuss important issues concerning the origin and evolution of the Caribbean Plate.

The third meeting was a field workshop on the Northern Caribbean Plate Boundary organized as part of the 4th Cuban Geological and Mining Congress (Havana, March 19-23, 2001). The workshop included both oral and poster presentations, focused mainly on the northern margin of the Caribbean plate in Cuba and its early geologic evolution. Participants came from Argentina, Canada, Chile, Colombia, Cuba, France, Great Britain, Italy, Mexico, New Zealand, Spain, and USA. A field trip to Central Cuba was held immediately after the Congress, March 24 to 27, in order to visit critical areas in the vicinity of Camagüey, central Cuba, where the northern Caribbean plate boundary is well exposed.

The fourth meeting was organized in Leicester, UK (April 23-24) as a Workshop on the Geochemistry of the Caribbean plateau and Cretaceous island arc terranes, and their implications for the geodynamics of the Caribbean. The Workshop hosted 35 participants from six countries (Colombia, United States, Italy, France, Germany and the UK). In addition, 30+ researchers from 5 other countries registered interest in the proceedings, but were not able to attend.

The fifth meeting was celebrated as part of the 4th North American Paleontological Covention (Berkeley June 26-july 2nd). The section chair (M. Iturralde-Vinent) was unable to attend the meeting because of last minute traveling complications. Several papers were presented concerning the paleontological data as a counter part to plate tectonic interpretation of the evolution of the Caribbean. The meeting was attended by about 15 persons, mostly from the USA.

2.4. Educational, training or capacity building activities
N/A

2.5. Participation of scientists from developing countries
We have been able to provide funding and fund seeking capabilities so a number of scientist from third world countries have been able to participate in the meetings, as is listed in the conference reports.

2.6. Publications
ABSTRACTS AND PRESENTATIONS
Anderson, T. H., Lidiak, E. G., and Jolly, W. T., 2001, Caribbean plate boundaries - Eocene subduction, collision and suturing in Puerto Rico: significance of the greate southern Puerto Rico fault zone [abs]: Geological Society of America Abstracts with Programs, v. 33, p. A-263.

Audemard, F. A., 2000, Major Active Faults of Venezuela. Program and Abstract 31 International Geological Congress, Rio de Janeiro, Brasil, 4 p.

Audemard, F. A., and Singer, A., 2000, Paleoseismology in Venezuela: an overview. Program and Abstract 31st International Geological Congress, Rio de Janeiro, Brasil, 4 p.

Cazañas, X., Proenza, J.A., Mattietti Kysar, G., Lewis, J., Melgarejo, J.C., 2000, Rocas volcánicas de la series Inferior y Media del Grupo El Cobre en la Sierra Maestra (Cuba Oriental). Volcanismo generado en un arco de islas tholeiítico: Tercera Conferencia Internacional Sobre la Geología de Cuba, el Golfo de México y el Caribe Noroccidental. Universidad de Pinar del Río, Cuba. p. 5.

García D. E., Rojas-Agramonte, Y., Díaz C., 2000, Estratigrafía del arco volcánico paleógeno en la región occidental de La Sierra Maestra, Cuba. XVII. Geowissenschaftliches Lateinamerika-Kolloquium, 11 bis 13 Oktober, Stuttgart, Germany

García Delgado D.E., Díaz Otero C., Méndez Calderón I., Rojas-Agramonte, Y., Delgado Damas R., 2000, Petrología y bioestratigrafía del arco volcánico paleógenico en la región meridional y oriental de la Sierra Maestra, Cuba. XVII. Geowissenschaftliches Lateinamerika-Kolloquium, 11 bis 13 Oktober, Stuttgart, Germany

Giunta G. Beccaluva L., Coltorti M., Siena F. and Mortellaro D., 2000, The Peri-Caribbean ophiotiles: structure, tectono-magmatic significance and geodynamic implications: International Geological Congress. Brazil 2000 (Abstract and poster).

Giunta G., Beccaluva L., Coltorti M., Mota B., Romero J., and Siena F., 2001, The Motagua Suture Zone in Guatemala, as northwestern border of the Caribbean Plate. GeoMin 2001; IGCP 433 Workshop, La Habana.

Giunta G., Beccaluva L., Coltorti M.,and Siena F., 2001, Tectono-magmatic significance of the main Ophiolitic units of the deformed margins of the Carbbean Plate: open problems on the geodynamic implications. IGCP 433, Caribbean Workshop, Leicester.

Iturralde-Vinent, M. A., 2001, Phanerozoic Tectonic Evolution Of The North American Plate Boundary In Cuba [abs]: Geological Society of America Abstracts with Programs, v. 33, p. A-154.

Iturralde-Vinent, M. and L. Gahagan, 2000, Caribbean Plate tectonic models: Discrepancies and Similarities. 31st International Geological Congress, General Symposium 17.6: Caribbean Plate Tectonics, Origin and Evolution, Rio de Janeiro, August.

Iturralde-Vinent, M. A., and Gasparini, Z., 2001, Paleontological evidence of the early evolution of the Caribbean Seaway: North American Paleontological Convention 2001: Theme Session Paleobiogeography, PaleoBios, v. 21, Supplement to No. 2, p. 17.

Kysar, G., Lewis, J. F., and Wysoczanski, R., 2001, Lead isotopic study of the Sierra Maestra, southeastern Cuba [abs]: Geological Society of America Abstracts with Programs, v. 33, p. A-304.

Lapierre, H.; Bosch, D; Mamberti, Dupuis, B.; Jaillard, E.; de Lépinay, B.; Maury, R.; Hernandez, J.; Polvé, M. and Tardy, M. 2001. The Late Cretaceous Duarte Complex (Hispaniola) revisited: comparison with the Cretaceous oceanic plateaus from Ecuador. Leicester meeting.

Lidiak, E. G., Anderson, T. H., and Jolly, W. T., 2000, Tectonostratigraphic evolution of southwestern Puerto Rico [abs]: 31st International Geological Congress, General Symposium 17.6: Caribbean Plate Tectonics, Origin and Evolution, Rio de Janeiro, Brazil, p. 193.

Lidiak, E. G., Anderson, T. H., and Jolly, W. T., 2001, Geologic evolution of the Bermeja Complex, southwestern Puerto Rico [abs]: IV Congreso Cubano de Geologia Y Mineria Geomin 2001, Habana, Cuba, March 2001, p. 16.

Pindell, J., 2001, The Pacific Origin of the Caribbean Plate, with emphasis on Cuba: In: Caribbean Workshop, University of Leicester, April 2001.

Pindell, J., and Lorcan, K., 2001, Kinematic Evolution of the Gulf of Mexico and Caribbean: In: GCSSEPM research conference, edited by Richard Fillon, Houston, December

Pindell, J., Lorcan, K., and Higgs, R., 2001, Tectonic Model for Eastern Venezuela and Trinidad since 12 Ma [abs]: AAPG National Meeting, Houston, Texas.

Pindell, J., Higgs, R., and Kennan, L., 2001, Paleogene "Negative Flexure" Basins in Colombia and Venezuela[abs]: AAPG National Meeting, Houston, Texas.

Pindell, J., and Draper, G., 2001, Evolution of the Cuban portion of the Caribbean Plate, Pacific origin to Bahamian collision [abs]: Geological Society of America Abstracts with Programs, v. 33, p. A-153.

Pindell, J., and Meneses-Rocha, J., 2001, Tectonic Evolution as a control on oil and gas distribution in Mexico: In: AAPG Conference, Veracruz, Mexico, November 2001.

Pindell, J., and Kennan, L., 2001, Tectonic Model for Eastern Venezuela and Trinidad since 12 Ma [abs]: AAPG National Meeting, Houston, Texas.

Pindell, J., Higgs, R., and Kennan, L., 2001, Paleogene "Negative Flexure" Basins in Colombia and Venezuela [abs]: AAPG National Meeting, Houston, Texas.

Proenza, J.A., Gervilla, F., Melgarejo, J.C., 2000, Los depósitos de cromita de la Faja Ofiolítica Mayarí-Baracoa (Cuba Oriental): Un resultado de procesos de zona de suprasubducción. Implicaciones en la prospección de cromititas: Tercera Conferencia Internacional Sobre la Geología de Cuba y el Golfo de México y el Caribe Noroccidental. Universidad de Pinar del Río, Cuba. p. 23-24.

Proenza, J.A., Melgarejo, J.C., Gervilla, F., 2000, La Faja Ofiolítica Mayarí-Baracoa (Cuba Oriental): una litosfera oceánica modificada en una zona de suprasubducción cretácica: Tercera Conferencia Internacional Sobre la Geología de Cuba, el Golfo de México y el Caribe Noroccidental. Universidad de Pinar del Río, Cuba. p. 23.

Rodríguez, R., Blanco-Moreno, J., Proenza, J.A., 2000, Petrología de las rocas plutónicas de afinidad ofiolíticas presentes en la zona de Cañete (Macizo Ofiolítico Mayarí-Baracoa, Cuba Oriental): Tercera Conferencia Internacional Sobre la Geología de Cuba, el Golfo de México y el Caribe Noroccidental. Universidad de Pinar del Río, Cuba. p. 25-26.

Rojas-Agramonte, Y., F. Neubauer, R. Handler, D. E. Garcia-Delgado, R. Delgado-Damas, 2000, Tectonic evolution of the Oriente fault seen trough the Deformation of The Sierra Maestra, Cuba, Geology 2000, Vienna, April 14-17, Austria

Rojas-Agramonte, Y., F. Neubauer, R. Handler, D. E. Garcia-Delgado, R. Delgado-Damas, 2000, Tectonic evolution of the Oriente fault seen trough the Deformation Of The Sierra Maestra, Cuba XVII. Geowissenschaftliches Lateinamerika-Kolloquium, 11 bis 13 Oktober, Stuttgart, Germany

Thompson, P.M.E.; Kempton, P.D.; Tarney, J.; Saunders, A.D.; White, R.V. and Kerr, A.C., 2001, New Isotopic and Geochronological Constraints on the Origin of an Island Arc Sequence Associated with the Cretaceous Caribbean Oceanic Plateau. Leicester meeting.

PAPERS
Audemard, F. A., 2001, Quaternary tectonics and stress tensor of the northern inverted Falcón Basin, northwestern Venezuela. Journal of Structural Geology, v. 23, p. 431-453.

de la Fuente, M. S., and Ituralde-Vinent. 2001, A new pleurodiran turtle from the Jagua Formation (Oxfordian) of western Cuba. Journal of Paleontology, v. 75 (4), p. 860-869.

García-Casco, A., Torres-Roldán, R.L., Millán G., Monié P. And Haissen, F., 2001, High-grade metamorphism and hydrous melting of metapelites in the Pinos terrane (W Cuba): evidence for crustal thickening and extension in the northern Caribbean collisional belt: Journal of Metamorphic Geology, in press.

Gasparini, Z. & Iturralde-Vinent, M., 2001, Metriorhynchid crocodiles (Crocodyliformes) from the Oxfordian of Western Cuba. Neues Jb. Geol. Palaont. Mh.

Gasparini, Z., Vignaud, P. & Chong, G., 2000, The Jurassic Thalattosuchia (Crocodyliformes) of Chile: a paleobiogoegraphic approach. Bull. Soc. géol. France, 171 (6): 657-664.

Grafe, F., Stanek, K. P., Baumann, A., Maresch, W. V., Hames, W. E., Grevel, C., and Millan, G., 2001, Rb-Sr and Ar/Ar mineral ages of granitoid intrusives in the Mabujina unit, Central Cuba: Thermal exhumation history of the Escambray Massif: Journal of Geology, in press.

Giunta G., Beccaluva L., Coltorti M., Siena F., andVaccaro, C., 2001, The southern margin of the Caribbean Plate in Venezuela: tectono-magmatic setting of the Ophiolitic units and kinematic evolution. Lithos (submitted).

Giunta G., Beccaluva L., Coltorti M., Siena F., Mortellaro D.,and Cutrupia D., 2001, The Peri-Caribbean Ophiolites: structure, tectono-magmatic significance and geodynamic implications. Sp. Vol. Caribbean Journal of Earth Science, Jamaica (in press).

Giunta G., Beccaluva L., Coltorti M., Siena F., Mortellaro D.,and Cutrupia D., 2001, Structure, tectono-magmatic setting of the Peri-Caribbean Ophiolites, and geodynamic implications:L Fed. It. Sc. Terra Geoitalia.

Giunta G., Beccaluva L., Coltorti M., and Siena F., 2000, Tectono-magmatic significance of the Peri-Caribbean ophiolitic units and geodynamic implications: 15th Caribbean Geological Conference; Jamaica, 1998 (in press).

Iturralde-Vinent, M.A., 1998, Sinopsis de la constitución geológica de Cuba. Acta Geológica Hispánica 33(1-4): 9-56. (actualy edited and published in 2000) .

Iturralde-Vinent, M. A., and Lidiak, E. G., 2001, Caribbean plate tectonics (IGCP 433): Gondwana Research, v. 4, p. 247-248.

Iturralde-Vinent, M.A., P.-K. Stanek, D. Wolf, H.U. Thieke, W. Muller, 2000. Geology of Camaguey, Central Cuba: Evolution of a collisional margin. Z. angew. Geologie, SH 1, p. 267-273

Jolly, W. T., Lidiak, E. G., Dickin, A. P., and Wu, T., 2001, Secular geochemistry of central Puerto Rican island arc lavas: constraints on Mesozoic tectonism in the eastern Greater Antilles: Journal of Petrology, v. 42, in press.

Maresch, W. V., Stöckhert, B., Baumann, A., Kaiser, C., Kluge, R., Krückhans-Lueder, G., Brix, M. and Thomson, S., 2000, Crustal history and plate tectonic development in the southeastern Caribbean: Z. Angew. Geol., v. SH1, p. 283-290.

Pessagno, E. A., Hull, D. M., and Hopson, C. A., 2000, Tectonostratigraphic significance of sedimentary strata occurring within and above the Coast Range ophiolite (California Coast Ranges) and the Josephine ophiolite (Klamath Mountains Northwestern California: Geological Society of America Special Paper 349, p. 383-394.

Proenza, J.A., Lewis, J.F., Melgarejo, J.C., Gervilla, F., Jackson, T., Jolly, W.T., Lidiak, E.G., 2001, Peridotites and chromitites in eastern Cuba, Jamaica, Hispaniola and Puerto Rico: a comparison of Jurassic-Cretaceous mantle sections within Caribbean region. 4to Congreso Cubano de Geología y Minería. La Habana. CR-ROM.

Rojas-Agramonte, Y., F. Neubauer, R. Handler, D. E. Garcia-Delgado, R. Delgado-Damas, 2001, Evolución tectónica de la falla Oriente vista a través de las deformaciones ocurridas en la Sierra Maestra. IV Cuban Geological and Mining Congress, Cuba, 2001. CD-ROM.

Stanek, K.P., Cobiella-Reguera, J., Maresch, W.V., Millàn Trujillo, G., Grafe, F., And Grevel, C., 2000, Geological development of Cuba: Z. Angew. Geol., v. SH1, p. 259-265.

MEMOIRS, PROCEEDINGS. AND GUIDEBOOKS
Pindell, J., 2001, Stratigraphy and structure of the northwestern Serranía del Interior Oriental, Venezuela: Constraints on dynamic evolution, Eastern Venezuela/Trinidad: In: Field Guide, 2001 International Field Trip of the Geological Society of Trinidad and Tobago.

Melgarejo and Proenza volume on Cuba 1998 (actually published year 2000 with updated information).

Seyfried, H. (ed.) 2000. Programa y Resúmenes Extendidos. XVII Simposio sobre la geología de Latinoamérica, Octubre 11-13, 2000, Stuttgart, Germany, Profil Band 18:1-6, and CD with extended abstracts.

OPEN FILE REPORT
Audemard, F. A., Machette, M., Cox, J., Hart, R. And Haller, K., 2000, Map and Database of Quaternary Faults in Venezuela and Offshore regions: U. S. Geological Survey, Open-File Report 00-18, 78 p.

WEB PAGE PRESENTATIONS
Iturralde-Vinent, M. and L. Gahagan, 2000, Caribbean Plate tectonic models: Discrepancies and Similarities. Web Page of the Institute for Geophysics of the University of Texas at Austin (www.ig.utexas.edu/CaribPlate/forum/forum.htm)
Iturralde-Vinent, M. and Z. Gasparini, 2001, Jurassic Paleogeography of west-central Pangaea; implications for the biogeography of marine biotas. Web Page of the Institute for Geophysics of the University of Texas at Austin (www.ig.utexas.edu/CaribPlate/forum/forum.htm)
Maresch, W. V., 2000, Pressure-temperature evolution of metamorphic rocks: records of a dynamic earth: (www.humboldt-foundation.de/de/aktuelles/index.htm)

2.7. Activities involving other IGCP projects or the IUGS
N/A

3. Activities planned
3.1.General goals.
In the year 2002 we plan to continue the debate over the issues concerning the origin and evolution of the Caribbean plate (Boston meeting Nov. 2001), with special emphasis in the plate boundaries in Central America (Guatemala meeting) and the Lesser Antilles Barbados meeting).

3.2. Specific meetings and field trips (please indicate participation from developing countries)
Geological Society of America Annual Meeting. Novenber 1-10, 2001. At the request of the IGCP and the GSA, we shall participate in the Annual Geological Society of America Meeting in Boston, Massachusetts. We have been invited to present papers at the GSA Topical Session "Focus on IGCP: Modern and Ancient Plate Boundaries and Orogens". Participation of Cuban, American, and other delegates will be partially supported by the project.

Motagua Fault Zone, Guatemala. January 28-31, 2002. The project will hold a Workshop and Field Trip to the Motagua Suture Zone of Guatemala. This event is being organized by the Italian-Caribbean Group, with the kind co-operation of the Sociedad Geologica de Guatemala and other Guatemalan institutions. Motagua suture zone in Guatemala is part of the northwestern boundary of the Caribbean plate and an important on-shore segment of the Caribbean plate boundary. The project will partially support the field transportation and the participation of delegates from Cuba, Guatemala, Costa Rica, Venezuela and USA.

16th Caribbean Geological Conference. June 16-21, 2002. The project will hold a Workshop and Field Trip during the 16th Caribbean Geological Conference, in Barbados, BWI. The purpose of this Workshop and Field Trip is to study and evaluate further the Lesser Antilles island arc, the easternmost boundary of the Caribbean plate. The project will support the field trip by covering the transportation expenses, and will support participants to the meeting from Cuba, Jamaica, Dominican Republic, Venezuela , Costa Rica, Guatemala, Mexico, USA, and other countries.

4. Project funding requested.
We will need the maximum possible funding in order to allow the participation of Latinamerican members of the project to the annual meeting in Barbados, as well as the other planned activities.

5. Request for extension, on-extended-term-status, or intention to propose successor project
N/A

6. Attach any information you may consider relevant
6.1 INTERNAL ORGANIZATION
The project is organized into several working groups. The leaders are Manuel A. Iturralde-Vinent (Museo Nacional de Historia Natural, Obispo no. 61, Plaza de Armas, La Habana 10100, Cuba; Email iturralde@mnhnc.inf.cu) and Edward G. Lidiak (Dept. of Geology & Planetary Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, U. S. A.; Email egl+@pitt.edu).

WG-1. Coordination Group. Leaders of the project and leaders of the working groups will integrate and coordinate the efforts of the membership of the project, organize meetings and workshops, keep the web page updated, and promote the accomplishments and goals of the project.

WG-2. Positioning of major plates: Jurassic to Recent. This group will evaluate existing models for the break-up of Pangaea and the evolution of the major plates surrounding the Caribbean (NOAM, SOAM, FARALLON, NAZCA, COCOS, etc.) from Jurassic to Recent. As a result they will provide the other working groups with a modern framework for the reconstruction of the Caribbean area.

WG-3. Positioning of terranes of Northern South America. This group will define plates, blocks and terranes, will identify the palinspastic evolution, historic position and relationships, and produce sets of time-framed reconstructions of the tectonic position of these terranes.

WG-4. Positioning of terranes of Southern North America. This group will define plates, blocks and terranes, will identify the palinspastic evolution, historic position and relationships, and produce sets of time-framed reconstructions of the tectonic position of these terranes

WG-5. Positioning of terranes of the Greater Antilles. This group will define plates, blocksnd Paleomagnetic control of the historic position of terrenes, plates and subduction zones. This group will evaluate the tectonic positions of Caribbean terranes, plates and subduction zones taking into account geochronology, geochemistry and paleomagnetics.

WG-7. Paleontological support of Caribbean Paleogeography. The purpose of this group is to study the fossil assemblages - marine and terrestrial - of different ages in distinct terranes, and identify the biogeographic and paleogeographic implications of its occurrences, with special focus on their input toward understanding the positioning of the terranes in selected time-frames.

WG-8. Geochronological, Geochemical and Paleomagnetic control of the historic position of terrenes, plates and subduction zones. This group will evaluate the tectonic positions of Caribbean terranes, plates and subduction zones taking into account geochronology, geochemistry and paleomagnetics.

WG-9. Origin, composition and age of the Caribbean oceanic lithosphere. This group will investigate the occurrence of oceanic crust of different ages within the Caribbean, both in the present marine basins and regions of obducted lithosphere.

NETWORKING
The network of the project is based on two main Internet sites, a WebSite (http://www.ig.utexas.edu/CaribPlate/CaribPlate.html) and an email discussion group (carib@yahoogroups.com).

The WebSite is intended to provide current information on Caribbean tectonics; it is updated generally every two months. At this site is found the full text of the project, references to papers dedicated to the Caribbean geology, direct access to existing Caribbean Plate Tectonic models, a list of forthcoming meetings and workshops, important news, and a forum section, which may be used to post questions and data related to specific topics. For example, presently in the forum are well-illustrated discussions of major problems associated with present tectonic models and the problems concerning the early opening of the Caribbean. Links to related WebSites may also be found. More than 3000 hits are recorded until August, 2001.

e-group was created in order to have a more active forum for the exchange of information. Subscribers to the Egroup will automatically receive all messages relevant to the project. The site is presently being used to direct attention to new information posted on the web, new publications, updates of forthcoming activities, and in a lesser degree, to post questions. As the project develops, the e-group has become an active forum for discussion of key geological problems and spread important information.

6.2 SCIENTIFIC MEETINGS AND WORKSHOP REPORTS

GENERAL SYMPOSIUM 17-6. CARIBBEAN PLATE TECTONICS, ORIGIN AND EVOLUTION. 31 INTERNATIONAL GEOLOGICAL CONGRESS, RÍO DE JANEIRO
August 6 to 17, 2000
Conveners: Manuel A. Iturralde-Vinent and Edward G. Lidiak

This symposium was dedicated to analyzing the present status of Caribbean Plate Tectonic models. Four special oral presentations and 12 posters were the subject of interesting debates and active exchange of data and interpretations.

The oral session, attended by more than 50 persons, was celebrated the morning of August 7th. Four special speakers presented their respective viewpoints concerning how they understand the formation and evolution of the Caribbean, but the fact is that each one produced a quite distinct scenario. In this regard, it is important to quote the senior convener, in the fact that "The Caribbean is a singular area of planet Earth, and therefore, it had had a single history". The plate tectonic models that explain the Caribbean plate as an allochthonous crust originated within the Pacific Ocean, was very well exemplified by the model of J. Pindell and L. Kennan. The special speaker Martin Meschede reviewed some shortcomings of recent Pindell's and Paul Mann's models, and presented his arguments for an in situ origin of the Caribbean plate. Another version of the in situ model was presented by Giuseppe Giunta (visit Comparison at CaribPlate Web Site). M. Iturralde-Vinent, as special speaker, evaluated the few similarities and many contradictions that exist among modern Caribbean Plate Tectonic models (visit Forum at CaribPlate Web Site). The in situ models were criticized because they have a problem of space in explaining the Cretaceous and early Tertiary Greater Antilles-Aves Ridge-Caribbean mountains subduction-related volcanic arcs. Some questions were also raised concerning the polarity of these arcs and the original position of some terranes of the Caribbean margins, subjects that will require more careful attention in the future.

Twelve papers were presented at the Poster Session which was held in the afternoon on both August 7th and 8th. They included three of the special oral presentations as well as new results from field research in key areas of Cuba, Puerto Rico, Venezuela, and Costa Rica. This session produced an active exchange of viewpoints among presenting authors, but also with many interested congress members.

The conveners and participants agreed that the symposium was an excellent forum for the most valuable exchange of ideas, but as exciting was the possibility to meet people based in different areas of the world with personal expertise and strong interest in the Caribbean. In terms of the scientific impact of the symposium, we concluded that despite the great amount of valuable information available about the Caribbean submarine and land areas, considerable research remains to be done in order to reach an agreement concerning the origin and evolution of the region. This way must be headed toward gathering new necessary hard data, but no less concern must be paid to the improvement of the conceptual basis of our interpretations. It is unfortunate that in many cases, we have been unable to agree even in the way we interpret the same set of data.

17 SYMPOSIUM ON THE GEOLOGY OF LATIN AMERICA (17TH LAK)
Institute for Geology and Paleontology, University of Stuttgart, October 11 to 13, 2000.
Convener: Hartmut Seyfried

A symposium on the Geology of Latin American countries, which dedicated several sessions to the geology and plate tectonics of the Caribbean area, was held at the Institute for Geology and Paleontology of the University of Stuttgart, Germany, from October 11 and 13 of year 2000. The symposium was attended by nearly 300 scientists from countries in South America, Central America, North America, Europe and also from Cuba. Presentations were made on the geology, paleontology, plate tectonics, seismicity and other geohazards, hydrogeology, and environmental issues concerning Mexico, Central America, Bahamas, Greater Antilles and South America. Among them were 12 oral and 13 posters dealing with different aspects of the geology, paleontology and plate tectonics of the Caribbean. A round table took place to discuss important issues concerning the origin and evolution of the Caribbean Plate. A visit was organized to the Paleontological Museum in Stuttgart, which has an elegantly designed exhibit of unique fossils showing excellent preservation with a highest quality of preparation.

This meeting, characterized by a high level of organization and strict attachment to the schedule, was a great opportunity to share opinions and to discuss hot issues of the Caribbean geology in general, and Central American and Greater Antilles geology in particular. Also it was a great possibility to meet with South and Central American geologists who, for different reasons, usually do not attend the Caribbean Geological Conferences (CGC) celebrated within the Caribbean area. It is the hope that in the future this situation will change for good, and more geologists from the countries surrounding the Caribbean Sea will attend the forthcoming meetings of the IGCP Project 433 and the CGC.

This conference highlighted once again the very different interpretations that still exist regarding fundamental issues concerning the origin and evolution of the Caribbean area. Let us comment briefly on some of these issues:

The Galapagos hotspot and the original position of the Caribbean Plate. There are two fundamental positions regarding the role of the Galapagos hotspot in the geology of the Caribbean. One holds that the Galapagos hotspot has nothing to do with the Protocaribbean crust or the Caribbean Plate (M. Meschede, J. Pindell), because it was always positioned west of both of them, and, consequently, was not the source of the so-called Caribbean plateau basalts. The other interpretation holds that the Galapagos hotspot actually produced the Caribbean plateau basalts and the ridges within the Nazca and Cocos plates (K. Hoernle). This divergence in opinion results from the general plate-kinematic framework chosen, so this is a problem that has to be focused on during future meetings of the IGCP-433.

Another problem addressed during the conference was the initial position of the Caribbean Plate (CARIB) with respect to the NOAM, SOAM and FARALLON plates. In this point there was a concurrence of opinions, because, regardless of the tectonic model chosen to explain the evolution of CARIB, authors agreed that the original location of CARIB was very near the Equator, a position that satisfies paleomagnetic results from Central America (W. Frisch, M. Meschede).

The alleged Albian-Campanian arc in Central America. One subject that did not find agreement during the meeting was the existence of an active Albian-Campanian island arc in Central America, and its evidence in the Nicoya Complex. According to a paper by Calvo and Bolz (1994), there is an arc-derived volcaniclastic calcalkaline section in Costa Rica, but several other attendees at the meeting (K. Hoernle, A. Astorga) stated that their geochemical and geological investigations in the Nicoya Complex do not confirm this.

A new plate-tectonic reconstruction by J. Pindell and L. Kennan presented during the symposium allows the existence of this arc, but others do not agree. An Albian-Campanian island arc as part of present-day southern Central America is a major issue concerning the geology of the Caribbean plate, because it will control the rate of relative eastward movement of CARIB, something that must have a strong bearing on the palinspastic reconstruction of the circum-Caribbean fold-belts. Therefore, this is a hot question to be faced in future IGCP-433 meetings.

The original position of Pinos, Escambray and Guaniguanico terranes of Cuba. The Pinos, Escambray and Guaniguanico terranes of Cuba were the subject of several presentations during the symposium, and a matter of interesting in-room and out-of-session discussions. Today there seems to be general agreement that these terranes are allochthonous to the Cuban foldbelt, so the important point to deal with is their origin. J. Pindell, L. Kennan and K.-P. Stanek hold the position that these terranes may have been part of the southern margin of the Maya (Yucatan) Block, facing the Pacific Ocean, while M. Iturralde-Vinent (1998) prefers an intra-Caribbean location, representing part of the proto-Caribbean crust. Current research in Cuba and the Dominican Republic by K.-P. Stanek, W.V. Maresch and their students and colleagues is producing important results, including several P-T-path records of rocks in the Escambray and related units, which will provide new clues on this subject. Bearing on this matter, the discovery by A. Schaffhauser and colleagues of Lower Cretaceous pelagic limestones in Belize, similar to those found in the isochronous sections of the Guaniguanico terrane, suggests that some Guaniguanico elements (or non-metamorphosed Escambray units) were located off Belize at least in the Lower Cretaceous (see also Hutson et al., 1999).

The Pindell and Kennan Caribbean plate tectonic model. J. Pindell and L. Kennan presented a new unpublished version of the Pacific origin of the Caribbean plate style of model, as two distinct papers. This model was also a subject of discussion during the first IGCP-433 meeting in Río de Janeiro. Many new important issues are reviewed in this new version, so it is much more comprehensive than previous ones, but several critical moments of the model are going to be debated in future meetings.

WORKSHOP ON THE NORTHERN CARIBBEAN PLATE BOUNDARY, 4TH CUBAN GEOLOGICAL AND MINING CONGRESS
Havana, March 22-27, 2001
Conveners: E. Lidiak and M. Iturralde-Vinent

A symposium and field workshop on the Northern Caribbean Boundary was held in Havana, Cuba, as part of the 4th Cuban Geological and Mining Congress (March 19-27, 2001). The symposium, which included both oral and poster sessions and which was held on March 22, focused mainly on issues concerning the complex northern margin of the Caribbean plate in Cuba and its early geologic evolution. Among participants where scientists from Argentina, Canada, Chile, Colombia, Cuba, France, Great Britain, Italy, Mexico, New Zealand, Spain, and USA.

A field trip to Central Cuba was held immediately after the Congress, March 24 to 27, in order to visit critical areas in the vicinity of Camagüey, central Cuba, where the northern Caribbean plate boundary is well exposed. This complex boundary near Camagüey encompasses elements of the passive continental margin, ocean crust and sediments, Cretaceous volcanic arc, as well as foreland and piggyback basins. The field excursion provided the participants with an excellent opportunity to examine in the field the structures and geologic relationships associated with this unique and critical tectonic boundary.

The purpose of the symposium was to focus on the characteristics of critical geologic terranes in central and eastern Cuba, Hispaniola, and Puerto Rico as they pertain to the northern Caribbean plate boundary in Cuba and to evaluate the present status of Caribbean plate tectonic models with respect to these field occurrences. Six special oral papers and 5 posters were presented. Each speaker was given 30 minutes, so extensive discussion followed each talk. These presentations were followed by a panel discussion period of several hours duration in which aspects of the northern plate boundary and the geology of Cuba were the subject of interesting debates and active exchange of data and interpretations.

The oral presentations and panel discussion was attended by a total of about 70-80 scientists. In the first presentation, M. Iturralde-Vinent (Cuba) gave an overview of the current state of plate tectonics in the Caribbean realm with special references to the geology of Cuba. He made the important point that detailed stratigraphic and tectonic data are critical to any viable plate tectonic model, but still there are many geologic units within the Caribbean, and specially in Cuba, whose origin and evolution is poorly understood, because the lack of modern studies. Therefore, understanding the Caribbean plate evolution will still require more field and laboratory research in key areas. Z. Gasparini (Argentina) then discussed the role of Jurassic marine reptiles in Cuba and their importance in evaluating early marine seaways in the early evolution of the Caribbean. This author suggested that the interchange of marine animals between western Tethys and the Pacific predate the break-up of Pangaea, as rocks of Lower and Middle Jurassic age yield fossils of marine reptiles in the eastern Pacific (Chile, Argentina, and in allochthonous terrains of Mexico, which show west-Tethyan affinities. The third and fourth presentations were made by G. Draper (USA). He discussed the high-pressure metamorphic rocks of central Cuba as metamorphic core complexes exposed as a result of low degree extensional faulting within the continental margin. He then discussed the early oceanic crustal terranes of central Hispaniola and the evidence they show for a mid-Cretaceous orogenic event and its possible relationship with the polarity subduction reversal of the Caribbean "Great Arc". G. Giunta (Italy) reported on the Motagua suture zone in Guatemala and its role as the northwestern boundary of the Caribbean plate. New geochemical data from the ophiolites suggest that there are both MORB and island arc complexes in the Motagua suture zone. The final oral presentation was made by J. Lewis (New Zealand) who described the tectonic and petrologic significance of peridotites and constituent chromitites as obducted fragments of contrasting mantle sections in the northern Caribbean region. These data, thou preliminary, indicate that the two large ophiolite outcrops of northeastern Cuba, yield distinct geochemical signature. M. Iturralde-Vinent then concluded with a discussion of the similarities and discrepancies that exist among the modern Caribbean plate tectonic models.

Posters presented as part of the northern Caribbean plate boundary Workshop included the following: New aspects of the geology of eastern Cuba (G. Millán-Cuba); Structural deformation phases at the northern plate boundary in Cuba (K. Nuñez-Cuba); Transitional marine environments in carbonate rocks of the Cretaceous volcanic arc of Cuba (R. Rojas-Cuba); Oceanic plagiogranites in Cuba (Sukar-Cuba); and Tectonic and geologic evolution of serpentinites in Puerto Rico (E. Lidiak-USA).

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 P-low 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 high-resolution 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

The aim of the Workshop was for the main research groups in this field to discuss recent research on the Caribbean region, specifically on the Cretaceous Caribbean plateau, the island arc terranes associated with it, and the tectonic evolution of the Caribbean region. The workshop lasted 2 days: the first day was focussed on the Mesozoic tectonic and structural evolution of the region whereas the emphasis on the second day was on the magmatic evolution and geochemistry of the Caribbean plateau, and the island arc terranes. cc6600The Workshop hosted 35 participants from six countries (Colombia, United States, Italy, France, Germany and the UK). In addition, 30+ researchers from 5 other countries registered interest in the proceedings, but were not able to attend. Some of the main research groups were:

1. Leicester, UK; represented by Kerr (now Cardiff), Saunders, Tarney, Thompson and White
2. Grenoble, France; represented by Arndt, Jaillard and Lapierre and Mamberti
3. Palmero, Italy; represented by Coltorti and Giunta
4. Regional tectonic analysis group, represented by Draper, Maresch, Pindell and Stanek

In total, 17 oral presentations were scheduled, though the emphasis was on informal discussion. To facilitate this, a long discussion session was scheduled at the end of each day, and the discussion chairs saught points to discuss from other participants prior to this.

First day: Geophysical and tectonic models
The chair of the first day's discussion was Roz White (Leicester), who led a discussion on how the geophysical and tectonic models discussed that day could fit in with the existence of the Caribbean plateau. It was agreed that Pindell's new comprehensive and detailed model for the tectonic evolution of the Caribbean did not rely on the presence of the Caribbean plateau: indeed the word plateau was never specifically mentioned in his talk. Plateau workers counteracted this by saying that a thick buoyant oceanic plateau would be very difficult to subduct, and would therefore significantly affect the tectonics of the Caribbean region, in particular the subduction polarity reversal. They cite the arrival of the buoyant and thick Caribbean plateau at the eastward dipping subduction zone as a mechanism for the flip, in a situation analagous to that seen in the Solomon Isles with the attempted subduction of the Ontong Java oceanic plateau. However, Pindell believes the subduction polarity reversal occurred at ca. 120 Ma (before the bulk of the plateau was formed), on the basis of the following pieces of evidence:

1. Abundant evidence for a large tectonic event around that time
2. Unconformities in many arc-related sequences at ca. 120Ma.
3. P-T paths from high-pressure metamorphic rocks
4. Change in geochemical character from PIA to CA in many circum-Caribbean arcs.
5. The earlier the flip occurred, the easier would occur tectonically. At 120 Ma, the arc would have been short and straight and there was a powerful potential mechanism available (the acceleration of the opening of the Atlantic. At 75 Ma, the arc was ~2000km in length, and may have been very highly arcuate in shape, which would require huge internal deformation as the convex side changes from the SW to the SE.

However, in the discussion it was conceded that there is growing evidence for an earlier (and possibly more voluminous (Diebold et al., 1999)) pulse of plateau magmatism around 130-120 Ma. If that is the case, an earlier plateau could have formed and caused the postulated subduction flip, and the later plateau building events (78, 90) could have represented the last pulses of magmatism.

Pindell's suggestion (pers. com.) was for plateau workers to suggest possible mechanisms for plateau emplacement within the 2500 km wide proto-Caribbean plate following the flip, with perhaps only the first ~300 km of the leading edge of the plate overlying the Benioff zone, hence allowing the Aruba batholith etc to be formed at 85-82 Ma. from subduction of normal oceanic crust beneath the plateau.

Second day's discussion focussed on the following areas:

1. The possible older 120Ma. pulse of plume magmatism. There appears to be growing evidence for it around the Carribbean (eg Lapierre, 2001; Diebold et al., 1999)
2. Whether the plateau was derived from the Galapagos plume. New palinispastic reconstructions say it's impossible (Pindell, 2001). Trace element and isotopic geochemistry, however, do not rule it out (Hauff et al., 2000)
3. The cause of the spread to high 87Sr/86Sr for the plateau lavas. Revillion (1999) analysed clinopyroxene separates from the Gorgona komatiites for Sr and concluded that it was primary as it correlates with the trace element abundances. This is supported by Kerr et al. (1996) who found that the high Sr composition of samples from the Curacao plateau sequence stayed constant with increased leaching and therefore attributed it to the incorporation of altered basalt into the source of the basalts. However, Thompson et al (2001) found that for the Upper Cretaceous arc lavas, which had initial 87Sr/86Sr of 0.7065, fresh apatite separates had much lower 87Sr/86Sr than the whole rock, and concluded that this spread to high 87Sr/86Sr was the result of alteration of the whole rock.
4. How Gorgona relates to the rest of the plateau. The Gorgona komatiites have a depleted eHf-eNd isotopic composition (Thompson et al. 2001), which is distinct from the rest of the Caribbean plateau. This suggests that they are sampling an additional depleted component. But we don't know the exact nature of their relationship to the rest of the plateau.
5. Does the plume source contain a non-DMM depleted component? There is growing evidence that the plume responsible for the Caribbean plateau contains a depleted component (eg Kerr et al, 1995). Thompson et al. (2001) have identified two depleted components using Hf-Nd systematics: a depleted component with an isotopic composition similar to MORB, and a depleted component with a high eHf of around +17. This component seems to be unique to Gorgona.

4TH NORTH AMERICAN PALEONTOLOGICAL COVENTION, SESSION T4 - CARIBBEAN MESOZOIC BIOGEOGRAPHY: PALEONTOLOGICAL CONSTRAINTS ON THE FORMATION AND EARLY EVOLUTION OF THE CARIBBEAN SEAWAY.
(BERKELEY, JUNE 30)
Convener: M. Iturralde-Vinent

This session was aimed at exploring the importance of the Early Jurassic to Cretaceous Caribbean biota for understanding the history of the opening of the Caribbean seaway and communications between the Pacific and Tethys. This biota includes invertebrates (ammonites, rudists, gastropods, calpionelids, etc.), plants, and marine vertebrates (pterosurs, plesiosaurs, turtle, crocodyles, pliosaurs, etc.) but is not well understood. This meeting was celebrated but did not fulfill expectations as a last moment inconvenience prevented M. Iturralde-Vinent from attending the conference (his presentation is posted at the web page of the project, under forum). Other presentation were directed to explain the movements of marine biotas across the Caribbean seaway, which are important data to constraint the utility of plate tectonic models. Several papers were presented concerning the paleontological data as a counterpart to plate tectonic interpretation of the evolition of the Caribbean. The meeting was attended by about 15 persons, mostly from USA.

REPORT ON THE GSA ANNUAL MEETING
BOSTON, NOVEMBER 5-8, 2001
Manuel Iturralde-Vinent

The GSA annual meeting in Boston was a great success and an unique opportunity to update ourself in the state of the art of the American Geology. Those particularly interested in the Caribbean participated in the IGCP-433 presentations presented in three different sessions (T3, Tectonics, and Igneous Petrology). The papers presented show the different points of view that characterize the Caribbean Plate tectonic scene today. As the abstracts included here are self explicative, further comment is not necessary other than to underline the point that as we gather more information about the Caribbean, more agreement is focused on the allochthonous origin of the Caribbean Plate, even though many contradictions remain on the details in further developing the model.

For this reason, during informal conversations during the meeting, we agree that the IGCP-433 annual session to be celebrated during the forthcomming Caribbean Geological Congress in Barbados (June, 2002), must focus in three main issues: 1) The Early Mesozoic evolution of the Caribbean, 2) The Early Tertiaty Evolution of the Caribbean, and 3) The interactions between the Caribbean Plate and South America.

Abstracts of the IGCP Project 433-Caribbean Plate Tectonics Presented at the GSA Annual Meeting in Boston

EVOLUTION OF THE NORTHERN PORTION OF THE CARIBBEAN PLATE: PACIFIC ORIGIN TO BAHAMIAN COLLISION
PINDELL, James, DRAPER, Grenville, KENNAN, Lorcan, STANEK, Klaus P., and MARESCH, Walter V.

Pacific origin models of Caribbean are more compatible with regional Caribbean geology than Intra-American models because (1) the Greater Antilles Arc (GAA) is older than the Central American Arc, which is predicted by Pacific, but not by Intra-American models; and (2) Caribbean tectonic interaction with northern Colombia and southern Yucatan began in the Campanian, which requires a more southwestward (Pacific) position of the Caribbean Plate before that time. We have refined earlier Pacific-derived Caribbean evolutionary models to new levels of precision and conclude: 1) the Galapagos Hotspot did not form the Caribbean plateau; 2) Early Cretaceous subduction dipped NE; 3) Panama-Costa Rica arc formed at equatorial latitudes; 4) Caribbean HP/LT metamorphic assemblages (except those of Jamaica) pertain to initiation and subsequent development of SW-dipping subduction beneath the GAA that followed an Aptian-early Albian subduction polarity reversal event; the new polarity then allowed the Caribbean Plate to enter the inter-American realm during Upper Cretaceous-Cenozoic; 5) the central Cuban Arc comprises mainly forearc elements of the GAA, and Sierra Maestra is more representative of the GAA axis; 6) Campanian cessation of magmatism in central Cuba resulted from shallowing of subduction as the GAA approached southern Yucatan, 7) the Yucatan intra-arc basin formed in two phases: Maastrichtian-Paleocene NW-SE extension driven by slab rollback of Jurassic Proto-Caribbean lithosphere along eastern Yucatan, and Early and Middle Eocene NNE extension driven by rollback of Proto-Caribbean crust toward the Bahamas, controlled by N-ward propagation of a NNE-trending east-Yucatan tear fault, during which western and northern Cuban terranes were accreted to the front of the central Cuban fore-arc; 8) Middle Eocene collision of all Cuban terranes with the Bahamas, and rapid uplift of the orogen after the detachment of the SW-dipping; 9) Eocene onset of Cayman Trough pull-apart as the Caribbean Plate began its well-known subsequent migration to its present position ;10) Oligocene transpression in Hispaniola and Puerto Rico which led to the ?Late Oligocene separation onset of separation of the Hispaniola arc assemblages from Oriente, Cuba.

PHANEROZOIC TECTONIC EVOLUTION OF THE NORTH AMERICAN PLATE BOUNDARY IN CUBA
ITURRALDE-VINENT, Manuel A.

In the Cuban territory crops out Phanerozoic rocks that contain stratigraphic sections of both the Bahamas and Yucatan borderlands of the North American continental margin. These sections can be subdivided into three tectonic stages as follow: 1. The Jurassic to latest Cretaceous passive margin stage, represented by siliciclastic and carbonate rocks sections that characterize the formation and early evolution of the Caribbean sea and its northern continental margin. This was a stage of extensional stress and evolution from intracontinental to open marine facies. 2. The to latest Eocene collisional margin stage, represented by foreland sediments with large amount of allochthonous materials (ophiolite and volcanic arc elements). During these stage took place strong compressional deformations. 3. The latest Eocene to Recent stage, characterized by less deformed sedimentary sections, mostly along the trend of wrench faults. In general represent post-collisional tectonics associated with transpresional and transtensional stress.

ASYMMETRIC SEAFLOOR SPREADING, CRUSTAL THICKNESS VARIATIONS AND TRANSITIONAL CRUST IN CAYMAN TROUGH FROM GRAVITY
TEN BRINK, Uri S., COLEMAN, Dwight F., and DILLON, William P.

With a few exceptions, oceanic crust, which forms atdivergent plate boundaries (and away from theinfluence of mantle plumes near hot spots), has nearly constant thickness regardless of age, geographiclocation, water depth, and spreading velocity. Using free-air gravity anomaly data, we model the crustal structure of the Cayman Trough to analyze theprocesses occurring at this slow-spreading mid-ocean ridge. Our model indicates considerable and abrupt crustal thickness variations along the trough axis, which parallels the direction of ocean opening. The proximal part to the spreading ridge extends ~170 km east of the spreading ridge and 250 km west of it. Sea floor in the proximal part is slightly deeper (by ~500 m) east of the ridge than west of the ridge, and crustal thickness east of the ridge is considerably thicker than the crust to the west. The distal part of Cayman Trough extends to a distance of ~300 km on both sides of the proximal part to the spreading ridge. It has a greater water depth and a thinner crust than the proximal part and it does not increase in depth away from the ridge. By tying our model to published seismic refraction data, we estimate the crustal thickness of the distal part to be 5.5 km and of the west and east sides of the proximal part as ~7 and ~9.5 km, respectively. To our knowledge, this is the largest crustal thickness contrast inferred across any spreading ridge, and it augments recent similar results from the SW Indian Ocean. We interpret the thin crust in the distal part as transitional crust formed by extreme attenuation without organized sea floor spreading, and the proximal part by crustal accretion at a slow spreading mid-ocean ridge. In the proximal part, there is an inverse relationship between the ratio of crustal thicknesses and the ratio of spreading rates east and west of the spreading center. We interpret this relationship to indicate that new material is accreted preferentially to an existing crust on the slow moving east side of this spreading system. Off-axis crustal accretion can take place either by lava flowing from the axis or by off-axis intrusions.

CENOZOIC ROTATION OF THE YUCATAN (MAYA) BLOCK ALONG THE ORIZABA FAULT ZONE OF SOUTHERN MEXICO AND THE FAULTS OF CENTRAL AMERICA
BURKART, Burke and SCOTESE, Christopher R.

Yucatan (Maya)has been an independent block since early Cenozoic when counter-clockwise rotation began that continues today. It is bounded in Mexico by the Orizaba fault zone (OFZ), which begins near the Gulf of Mexico at the Santa Ana massif, runs along the western Isthmus of Tehuantepec, crosses the northern Gulf of Tehuantepec W of the Chiapas massif, and connects with the major faults of Guatemala and the Cayman trough. Faults of Guatemala and adjacent Honduras are boundaries to wedges whose eastward rotation has been away from the Cuicateco terrane of Oaxaca, Mexico. Dextral slip of about 340 km across the OFZ is measured by offset of Laramide structures and Mesozoic and Tertiary contacts of the northern Chiapas massif from those in the fold and thrust belt of the Sierra Madre Oriental. Reversing the Cenozoic counter-clockwise rotation and simultaneously restoring previously-known sinistral offset across the Polochic fault of 130 km, moves the westernmost part of the tapered block between the Polochic and Jocotan faults (Chuacus-Tambor block) of Guatemala to a position between the Yucatan and Guerrero blocks about 160 km NW of the Pacific coast. Very little offset occurred across the Motagua fault zone. The northernmost part of the Chiapas massif is moved NW across the Isthmus to near the Santa Ana uplift near the Gulf of Mexico. Ophiolites, granitoids, metasedimentary rocks and volcaniclastics related to Cretaceous arc magmatism found in the Cuicateco terrane of Oaxaca and Tambor of Guatemala are juxtaposed with this restoration model. Obduction during strike-slip movement may account for wider distribution of ophiolites of Guatemala, which were obducted during strike-slip movement. The eastern Veracruz basin opened during rotation of the Yucatan block. Sinistral offset across the Chiapas Strike-Slip fault zone may reflect partial decoupling from the rest of the Yucatan block. The western basin (Cordoba platform) was dropped downward at an early stage of rotation.

EVOLUTION OF THE CRETACEOUS TO RECENT OROGENIC BELT OF NORTHERN VENEZUELA
SISSON, Virginia B. and AVÉ LALLEMANT, H. G.

The Caribbean Mountain system (Venezuela) is both a Modern and Ancient Plate Boundary and Orogen. At first glance, this mountain range appears to be a classical orogenic belt with a metamorphic "Hinterland" and a non-metamorphic "Foreland" fold and thrust belt. However, extensive dating (mostly ⁴⁰Ar/³⁹Ar) indicates that metamorphism of the hinterland belt took place in mid-Cretaceous time, whereas the non-metamorphic foreland rocks were deformed in Cenozoic time. This situation resulted from marked right-oblique convergence of the Caribbean and South American plates along their mutual EW-trending plate boundary zone. metamorphic rocks contain blueschists and eclogites and have formed in the Leeward Antilles subduction zone along which the Atlantic plate was subducted. Blueschists and eclogites were partially exhumed by arc-parallel stretching resulting from displacement partitioning along an oblique plate margin. The collision of the Leeward Antilles arc with South America resulted in obduction of the accretionary wedge onto the South American margin and change of subduction polarity. This obduction took place in Paleocene time in the west and is still occurring in the east. The development of foreland basins and the foreland fold and thrust belt was diachronous as well and young from west to east. The oblique convergence rate vector was strongly partitioned into a plate-boundary normal component that resulted into the south-vergent fold and thrust belt and a plate-boundary parallel component resulting in boundary parallel right-lateral strike slip faults along which the metamorphic belts were displaced toward the east. In addition, subduction related processes vary along strike. In the west, two high-pressure belts (Cordillera de la Costa and Villa de Cura belts) occur whereas in the east, (Margarita Island) only one exists. The Cordillera de la Costa belt contains eclogites that were formed at ~70 km depth. Eclogites on Margarita formed at ~45 km depth. The Villa de Cura belt blueschist formed at ~30 km depth. The age of exhumation varies from mid-Cretaceous (Villa de Cura and Margarita) to Eocene (Cordillera de la Costa). The dependence of depth of metamorphism and timing of exhumation of these high-P rocks on plate tectonic configuration is complicated, because of Tertiary overprint.

INTERCRATONIC OROGENS: THE CARIBBEAN AND SCOTIA ARCS
DALZIEL, Ian W.D., LAWVER, Lawrence A., GAHAGAN, Lisa M., and MANN, Paul

The Caribbean and Scotia arcs are two striking features of any tectonic map of the Earth and are in fact nearly identical in size. They are respectively located between North and South America, and South America and Antarctica, joining the North American Cordillera to the Andes, and the Andes to the West Antarctic continental margin orogen. Their tectonic evolutions can be related to the relative motion between the two pairs of cratons. Their evolving physiography produced critical controls, varying with time, on the movement of biota between the cratons, and between the Pacific and Atlantic Oceans. The Caribbean arc differs from the Scotia arc with the presence of the Central American land bridge. Yet differential motion along the Shackleton Fracture Zone between Cape Horn and the tip of the Antarctic Peninsula has produced a ridge as shallow as 700 meters. This ridge with only minor changes in plate motions could develop into a subduction zone and generate an island arc. Absence of a South America-Antarctica land bridge permits a complete and vigorous wind-driven circum-Antarctic current and intense sediment scour in Drake Passage. Cenozoic magnetic anomalies have been identified in Drake Passage and the eastern Scotia Sea where oceanic crust was formed as Antarctica separated from South America. High sedimentation rates, possible formation during the Cretaceous Normal Superchron, and a large igneous province obscure the equivalent history of the older Caribbean arc and seafloor. The nature and tectonic history of these 'fusible orogenic links' between the continental margin cordilleras of the western Americas and Antarctica are considered as are their evolutions in terms of possible 'mantle return flow' from the Pacific Ocean basin to the Atlantic Ocean basin. Possible analogs to the ancient geologic record such as a link between the Ordovician Taconic and Famatinian arcs of North and South America are also considered.

3-D GRAVITY ANALYSIS OF THE N.E. CARIBBEAN AND THE DEVELOPMENT OF THE PUERTO RICO TRENCH
MARTIN, Jennifer L., TEN BRINK, Uri S., DILLON, William P., and NEALON, Jefferey W.

A 500-km long section of the carbonate platform north of Puerto Rico and the Virgin Islands collapsed simultaneously sometime after 3.4 Ma to a maximum depth of 4.5 km. This sudden subsidence, which may be associated with the formation of the Puerto Rico Trench, is puzzling given that the direction (ENE) and the rate (~20 mm/y) of North American (NOAM)-Caribbean plate motion in this area has remained constant during the past 45 Ma. The collapse has been attributed to subduction erosion, to a tear in the downgoing NOAM plate in the area of maximum curvature, and to an interaction at depth between the flaps of the Caribbean and NOAM plates. We modeled the gravity field in the NE Caribbean in 3-D with the simplifying assumption that the sources of the anomaly are only due to the water-crust and crust-mantle interfaces. Consistent results were obtained by modeling in the space domain (CordellÕs method) and in the wave number domain (ParkerÕs method). A 2-D model along a 350-km-long seismic profile across this plate boundary was also compared with the 3-D model results. The gravity model indicates that a 25±5 km thick crust extends from Puerto Rico northward under the collapsed area to just south of the Puerto Rico Trench. The thick crust is not an artifact of excluding low-density sedimentary rocks from the model, because there is no evidence in seismic reflection data for an appreciable accretionary prism south of the trench. Moreover, dredging has recovered arc-related metamorphic rocks and limestone, similar to those found in Puerto Rico, at a depth of 7100 m south of the trench. The gravity model suggests that the entire crust north of Puerto Rico has been tilted northward. A whole-crustal tilt requires space to be created by a sudden removal of the foundation. One possibility is that the NOAM plate flap, which underlies Puerto Rico and the Virgin Islands has suddenly increased its dip or rolled back. Either of these options will pull down the overlying crust if the interface between them has high friction, which allows shear stresses to build up. The existence of a large negative gravity anomaly (-355 mGal), more negative than in typical trenches is consistent with this interpretation. Large magnitude earthquakes may occur at the interface between the Caribbean and the NOAM plate if the interface can support high shear stresses.

CARIBBEAN PLATE BOUNDARIES - EOCENE SUBDUCTION, COLLISION AND SUTURING IN PUERTO RICO: SIGNIFICANCE OF THE GREAT SOUTHERN PUERTO RICO FAULT ZONE
ANDERSON, Thomas H., LIDIAK, Edward G and JOLLY, Wayne T.

The northern margin of the Caribbean plate is distinguished by the southeastward curving Greater Antillean (GA) arc. Volcanism above the south-facing zone ceased after the western Cuba segment of the arc collided with the Bahamas platform between 66 and 44 Ma. In eastern Cuba, Hispaniola and attached islands to the south collisional structures are less prominent because of the southeastward curvature of the GA arc away from the Bahamas Platform. South of the Cauto fault in Oriente Province, Eocene igneous rocks crop out as they do in Hispaniola and Puerto. In Puerto Rico, Eocene lavas and plutons are most common among northwesterly striking faults that distinguish the Great Southern Puerto Rico fault zone (GSPRFZ). Tertiary strata include lavas, volcaniclastic and other sedimentary units some of which are fine-grained and cherty and may be pelagic. Well layered strata may contain olistoliths and commonly record faults and folds some of which may be penecontemporaneous. Older, Late Cretaceous rocks covering the oceanic crust southwest of the GSPRFZ may have been offscraped and deformed as they were carried toward the trench. Subduction related Eocene volcanism was areally limited and short-lived. Convergence waned during Oligocene time perhaps in response to the arrival and collision of thick oceanic terrains (eg. Cayman Ridge, Nicaraguan Rise, Beata Ridge) with the overriding plate. During collision, volcanic units at the edge of the overriding crust were uplifted and destabilized sufficiently so that masses calved off and collapsed southwestward forming an apron of debris (Sabana Grande Formation). We propose that the Eocene volcanic rocks record renewed subduction, although the subduction was north-facing and involved the consumption of the Caribbean plate along a zone roughly coincident with the back arc of the Cretaceous belt.

STRUCTURAL STYLES ALONG OBLIQUELY CONVERGENT OROGENS: THE EASTERN CARIBBEAN-SOUTH AMERICA PLATE BOUNDARY
CRUZ, Leonardo, TEYSSIER, Christian, and WEBER, John

The Caribbean-South America plate boundary in NE Venezuela and northern Trinidad exposes an E-W oriented mountain belt of deformed and metamorphosed sediments deposited on the northern South America passive margin in early Mesozoic time. Northern Trinidad and NE Venezuela display contrasting styles of deformation developed during oblique collision and wrenching between the Caribbean and South American plates in the past 50 million years. In northern Trinidad, metamorphic conditions increase from east to west with structures evolving from upright in the east to recumbent in the west, across the brittle-ductile transition. In ductilely deformed rocks, foliation is subhorizontal and lineation is ~E-W, parallel to the belt. Sense of shear is ambiguous. In NE Venezuela, metamorphic grade is similar to the western part of northern Trinidad; foliation dips moderately to steeply to the S and lineation plunges moderately to the SW. In general, sense of shear criteria parallel to lineation show top (down) to SW relations, indicating increased exhumation of the northern part of the belt. Oblique collision and wrenching in the Caribbean-South American plate boundary may have generated a complex deformation history, which evolved diachronously from west to east to produce the two styles of deformation displayed in northern Trinidad and NE Venezuela. Two models have been proposed to account for the generation and exhumation of this belt. In the first model, deformation is concentrated in a retro-wedge developed in front of the rigid Caribbean plate indenter, which deformed the softer South American continental crust. Vertical stretch decreases southward, exhumation rate increases to the north and deformation ages are younger to the east due to diachronous collision. The second model implies a midcrustal coupling zone that deforms ductilely due to translation of upper crustal blocks and transpression of the system. Subhorizontal fabrics develop contemporaneously parallel to the rheological layering of the lithosphere. For both models, spatial and kinematic variations of fabric orientation, cooling ages, and exhumation rates, are key elements to understand the overall deformation history of this region and are currently being studied.

LEAD ISOTOPE STUDY OF THE PALEOGENE IGNEOUS ROCKS OF THE SIERRA MAESTRA, SOUTHEASTERN CUBA
KYSAR MATTIETTI, Giuseppina, LEWIS, John F., and WYSOCZANSKI, Richard

Sierra Maestra of southeastern Cuba occupies a key position between the remnants of the Greater Antilles arc accreted terranes and the Cayman strike-slip belt that constitutes the present day northern Caribbean plate boundary. An isotopic study has been undertaken to constrain the paleotectonic setting and the source of the Sierra Maestra structure. Lead isotope ratios were determined for a set of lithologies representative of each major magmatic complex of the Sierra Maestra. Both ^207Pb/204Pb and ²⁰⁸Pb/²⁰⁴Pb ratios are restricted to a narrow, well-defined array of values in a band parallel to the North Atlantic Reference Line NHRL The slight enrichment in ²⁰⁷Pb/²⁰⁴Pb ratios represent the selective mobilization U with respect to Th, (U/Th ratios ranges from 0.8 to 1). Overall Pb isotope ratios for the Sierra Maestra are homogeneous, indicating the existence of a single magma source. This observation correlates with the low Ce/Yb values that characterize primitive arcs with varying degrees of the PREMA (Primitive fertile mantle) component. There is a overlap between the isotopic ratios of the Sierra Maestra and the Cretaceous island arc tholeiites of Puerto Rico indicating that the Paleogene arc rocks have a similar mantle source.

Site	Rock Type	206Pb/204Pb	207Pb/204Pb	208Pb/204Pb	SiO2
Daiquiri	Gabbro	18.719	15.591	38.33	48.36
Daiquiri	Qz-diorite	18.919	15.571	38.402	63.29
Daiquiri	Andesite	18.983	15.597	38.516	57.4
Nima-Nima	Qz-diorite	18.991	15.625	38.566	64.01
Nima-Nima	Basalt	18.672	15.592	38.329	51.22
Guama	Qz-diorite	19.107	15.635	38.723	62.52
Guama	Bas-And.	18.977	15.627	38.519	54.98
Turquino	Gr-diorite	19.29	15.634	38.719	74.62
Turquino	Basalt	18.818	15.596	38.385	50.89
Turquino	Diabase	18.879	15.581	38.344	51.52
Turquino	Qz-diorite	18.506	15.597	38.119	51.59

Related abstract

ANIMATION OF PLATE MOTIONS AND GLOBAL PLATE BOUNDARY EVOLUTION SINCE THE LATE PRECAMBRIAN
SCOTESE, Christopher R.

A computer animation will be presented that illustrates both plate motions and the evolution of plate boundaries since the Late Precambrian. Plate motions during the Jurassic, Cretaceous and Cenozoic plate motions are based on linear magnetic anomalies and the tectonic fabric of the ocean floor revealed by satellite altimetry, in combination with "absolute" motion trajectories determined by the Indian and Atlantic hotspot tracks and paleomagnetism. Early Mesozoic, Paleozoic and Late Precambrian plate tectonic reconstructions, however, are less well constrained and are based on less precise paleomagnetic data, lithologic indicators of climate, biogeographic inferences, and the timing of continental rifts and collisions. In addition to the motion of the plates, the animation shows the continuous evolution of global plate boundaries. Though the rifts and subduction zones associated with the breakup of Pangea are well known, the pre-Mesozoic plate boundaries shown here are speculative. Their location is based on the timing of rifts and continental collisions inferred from the geologic record, and the fundamental assumption that plates move as a result of slab pull and ridge push. For example, fast moving plates must be attached to old, cold subducting slabs. Large continental plates (Eurasia), on the other hand, tend to move slowly because of deep lithospheric keels. The evolving geometry of plate boundaries controls the tempo and mode of plate evolution. The history of plate motions might be best described as "long periods of boredom, interrupted by short intervals of terror (rapid change)". Episodes of global plate reorganization punctuate long periods of steady-state plate motion. reorganizations are due to catastrophic changes in plate boundary geometry that result in new lithospheric stress regimes. One of the most important plate boundary events is the subduction of a spreading center. The subduction of the Tethyan Ridge in the Jurassic may have been responsible for the breakup of Pangea.

REFERENCES CITED
Calvo, C., and Bolz, A., 1994, The oldest calcalkaline island arc volcanism in Costa Rica. Marine tephra deposits from the Loma Chumico Formation (Albian to Campanian). In Seygfried and W. Hellmann (Ed.) Geology of an evolving island arc. Profil Band 7, Inst. Geol. And Paleont., Univ. Stuttgart, 235-264.

Diebold, J.; Driscoll, N. and EW-9501 Science team, 1999, New insights on the formation of the Caribbean basalt province revealed by multichannel seismic images of volcanic structures in the Venezuelan basin. In: Caribbean Basins, edited by Mann, P., Elsevier, Amsterdam.

Hauff, F., K. Hoernle, et al., 2000, Age and geochemistry of basaltic complexes in western Costa Rica: contributions to the geotectonic evolution of Central America. G cubed 1 (May 30).

Hutson, F., Mann, P., Renne, P., 1999, 40Ar / 39Ar dating of single muscovite grains in Jurassic siliciclastic rocks (San Cayetano Formation): Constraints on the paleoposition of western Cuba. Geology, 26(1), 83-86.

Iturralde-Vinent, M. 1994, Cuban Geology: A new plate tectonic synthesis: Journal of Petroleum Geology, v. 17, p. 39-70.

Iturralde-Vinent, M., 1998, El segmento cubano del arco volcánico paleoceno-Eoceno medio del Caribe, en W. Ali, A. Paul y V. Young On, eds., Transactions of the 3rd Geological Conference of the Geological Society of T & T and The 14th Caribbean Geological Conference, T & T, 1995, Vol. 1, p. 343-362

Jolly, W. T., Lidiak, E. G., Schellekens, J. H., and Santos, H., 1998, Volcanism, tectonics, and stratigraphic correlations in Puerto Rico, in Lidiak, E. G., and Larue, D. K., eds., Tectonics and Geochemistry of the Northeastern Caribbean: Boulder, Colorado, Geological Society of America Special Paper 322, p. 1-34.

Kerr, A. C., Saunders, A.D., Tarney, J., Berry, N.H. & Hards, V.L., 1995, Depleted mantle-plume geochemical signatures: no paradox for plume theories. Geology 23(9): 843-846.

Kerr, A. C., Tarney, J., Marriner, G.F., Klaver, G.Th, Saunders, A.D & Thirlwall, M.F., 1996, The geochemistry and petrogenesis of the late-Cretaceous picrites and basalts of Curaçao, Netherlands Antilles: a remnant of an oceanic plateau. Contributions to Mineralogy and Petrology 124: 29-43.

Kerr, A.C,; Iturralde-Vinent, M.A., Saunders, A.D.; Babbs, Tanya L. and Tarney, J., 1999, A new plate tectonic model of the Caribbean: Implications from a geochemical reconnaissance of Cuban Mesozoic volcanic rocks. Geological Society of America Bulletin, 111 (11): 1581-1599.

Kerr, A.C.; Marriner, G.F.; Arndt, N.T.; Tarney, J.; Nivia, A.; Saunders, A.D. and Duncan, R.A., 1996, The petrogenesis of Gorgona komatiites, picrites and basalts: new field, petrographic and geochemical constraints. Lithos 37, 245-260.

Lawver, L.A., M.F. Coffin, I.W.D. Dalziel, L.M. Gahagan, and R.M. Schmitz, 1999, Atlas of Paleogeographic reconstructions. PLATES Progress Report No. 35-0799, University of Texas Institute for Geophysics, 84 p.

Mann, P., 1999, Caribbean sedimentary basins: classification and tectonic setting from Jurassic to Present. In P. Mann (Ed.) Caribbean Basins, (Seies ed. K.J.Hsü) Sedimentary basins of the World 4. Elsvier Science B.V. Amsterdan. p. 3-31.

Mattson, P. H., 1979, Subduction, buoyant braking, flipping and strike-slip faulting in the northern Caribbean: Journal of Geology, v. 87, p. 293-304.

Pindell, J. L., 1994, Evolution of the Gulf of Mexico and the Caribbean, in Donovan, S. K., and Jackson, T. A., eds., Caribbean Geology: An Introduction: Kingston, Jamaica, University of West Indies Publishers' Association, p. 13-39.

Pindell, J. L., 2001, Origin of Caribbean terranes in a kinematic framework: 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, 2001.

Revillon, S.; Arndt, N. T. et al. 2000, Geochemical study of ultramafic volcanic and plutonic rocks from Gorgona island, Colombia: the plumbing system of an oceanic plateau. J. Pet 41(7): 1127-1153.

Sigurdsson, H., M. Leckie, G. Acton y ODP Leg 165 scientific party, 1997, Proceedings of the Oceanic Drilling Program. Initial Report of Ocean Drilling Project Leg 165. College Station TX: Ocean Drilling Program.

Thompson, P.M.E.; Kempton, P.D.; Tarney, J.; Saunders, A.D.; White, R.V. and Kerr, A.C., 2001, New Isotopic and Geochronological Constraints on the Origin of an Island Arc Sequence Associated with the Cretaceous Caribbean Oceanic Plateau: 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, 2001.