WESTERN-CARIBBEAN Phanerozoic Tectonic Deformations as Recorded in the Cuban Foldbelt

1. WESTERN-CARIBBEANPhanerozoic Tectonic Deformations as Recorded in the Cuban Foldbelt ITURRALDE-VINENT, Manuel A. Museo Nacional de Historia Natural, Obispo no. 61, Plaza de Armas, La Habana 10100 Cuba, iturralde@mnhnc.inf.cu

2. Many tectonic elements which today built-up the Cuban foldbelt, originally where part of the Mesozoic North American passive margins and the Proto-Caribbean and Caribbean crusts. They are represented by the Bahamian-North Cuban foldbelt, the Cuban Southwestern Terranes and the Northern Ophiolites.

3. The North American continental margin units crops out along the northern half of the island (Bahamian borderland) and as the Cuban Southwestern terranes (Mayan borderland). Bahamian borderland Mayan (Yucatan) borderland

4. In the sections of the Bahamian borderland there is no record of Mesozoic tectonic deformation or regional metamorphism. Deformation and very low degree of metamorphism took place only during the Early Tertiary (Paleocene-Eocene).

5. The Mesozoic stratigraphy of both the Guaniguanico and Escambrayterranes are very similar, but the Pinos terrane differ in representing a more continental-ward set of siliciclastic and carbonate rocks. An important distinction in the Mesozoic geological history of these terranes is the age of their tectonic deformations and metamorphism.

6. In the Guaniguanico terrane there is no record of Mesozoic tectonic deformation or regional metamorphism. Deformation took place during Paleocene and early Middle Eocene. The Escambray and Pinos terranes suffered deformation and metamorphism during the Cretaceous. K-Ar datings in these terranes record thermal events at the end of the Cretaceous (Pinos 78 - 65 Ma; Escambray 85 - 65 Ma). Ar-Ar and U-Pb dating record ages around 100 Ma.

7. Age of the deformations in the continental margin areas The deformations of the North American continental margin took place in progression from Cretaceous to Late Eocene.

8. ORIGINAL POSITION OF THE CUBAN TERRAINS BAHAMAS Guaniguanico Pinos Escambray

9. The deformations along the continental margins of North America have some important implications: 1. Is quite probably that these deformations record the interaction between the North American Plate (NOAM) and the Caribbean Plate (CARIB). 2. The oldest deformations are recorded in the Pinos and Escambray terranes, suggesting that they were the first to interact with CARIB. 3. The youngest deformations are identified along the Guaniguanico terrane and the Bahamian borderland, recording the so called CARIB “collision” with the Bahamas.

10. Cuban ophiolites Within the Northern Cuban Ophiolites occur inclusions of HP/LT metamorphic rocks, including metasedimentary ones, whose K-Ar age range from 126±9.6 - 67 ±10.4 Ma.

11. Deformations within the Volcanic Arcs Cretaceous arcs Paleogene arcc Within the sections of the volcanic arcs can be recorded a number of regional deformational events. These deformations took place during the Aptian, Coniacian-Santonian, late Campanian, Maastrichtian-Paleocene and Middle Eocene. Every deformation is associated with local hiata, conglomerates, changes in the geochemistry of the magmas, and with plutonite emplacement -sometimes very large as during the latest Cretaceous and the Middle-Late Eocene.

12. The deformations within the Northern Ophiolites and the Volcanic Arcs have additional implications: 1. Is quite probably that these deformations record intraplate tectonic events of the Caribbean (CARIB) and Proto-Caribbean Plates (P-CARIB). 2. The fact that P-CARIB elements (Northern ophiolites) suffered deformations since the Early Cretaceous, suggest that this plate had had a rather complicate history. 3. The punctuated deformations recorded within the volcanic arcs since the Aptian, imply that the Arc terranes were deformed way before the “collision” with the Bahamas.

13. Paleogeographic evolution of the continental margins

17. Late Cretaceous paleogeography of the continental margin Cretaceous deformation and metamorphism NORTHERN OPHIOLITES ESCAMBRAY TERRANE PINOS TERRANE

18. Paleocene paleogeography of the continental margin

19. Eocene deformation of the continental margin Progressive deformation of the continental margin

20. CONCLUSIONS 1. The deformations along the borderland of the Maya block took place from SW to NE, starting in the Cretaceous (Pinos and Escambray terranes) and lasted until the Middle Eocene (Guaniguanico terrane). 2. The deformations along the Bahamian borderland took place from West to East, and embrace only the Paleocene-Late Eocene. 3. The deformations of the Northern Ophiolites took place from South to North, and lasted since the Cretaceous and until the Late Eocene.

21. 4. These facts corroborate the Plate Tectonic models which require that the present Caribbean Plate originated West of Pangaea, to became intercalated between North and South America since the Cretaceous. 5. Nevertheless, the same results also represent a problem for the most common Caribbean models, because none of them explain why the Bahamian borderland is deformed only during the Paleogene, while the ophiolites for a long period of time since the Early Cretaceous.

22. This is a contribution to IGCP Project 433: "Caribbean Plate Tectonics"

23. To learn more of this project visit our web page www.ig.utexas.edu/CaribPlate/CaribPlate.htm