Changes

[[File:Cuba_rel94.jpg|thumb|300px|Map of Cuba. This image is a work of a Central Intelligence Agency employee, taken or made as part of that person's official duties. As a Work of the United States Government, this image or media is in the public domain.]]

[[File:Cuba_rel94.jpg|thumb|300px|Map of Cuba. This image is a work of a Central Intelligence Agency employee, taken or made as part of that person's official duties. As a Work of the United States Government, this image or media is in the public domain.]]

The geology of Cuba has been a challenge to geologists because of features such as the presence of well-preserved [[Jurassic]] [[ammonite]]s, the rich [[Tertiary]] [[foraminiferal]] faunas (including remarkable [[Paleogene]] [[orbitoids]]), the gigantic Upper [[Cretaceous]] [[rudistids]], the spectacular limestone Mogotes of Pinar del Rio, the extensive [http://www.merriam-webster.com/dictionary/outcrop outcrops] of [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasic] [[Igneous rock|igneous]] rocks, the [[chromite]] and [[manganese]] deposits, and the extraordinary structural complexity. In addition to these features, the numerous petroleum seeps, many of them coming out of [[Wikipedia:Basic_rock|basic]] igneous rock, have attracted much attention.

The geology of Cuba has been a challenge to geologists because of features such as the presence of well-preserved [[Jurassic]] [[ammonite]]s, the rich [[Tertiary]] [[foraminiferal]] faunas (including remarkable [[Paleogene]] [[orbitoids]]), the gigantic Upper [[Cretaceous]] [[rudistids]], the spectacular [[limestone]] Mogotes of Pinar del Rio, the extensive [http://www.merriam-webster.com/dictionary/outcrop outcrops] of [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasic] [[Igneous rock|igneous]] rocks, the [[chromite]] and [[manganese]] deposits, and the extraordinary structural complexity. In addition to these features, the numerous petroleum seeps, many of them coming out of [[Wikipedia:Basic_rock|basic]] igneous rock, have attracted much attention.

==Geologic history==

==Geologic history==

[[Paleogeography|Paleogeographic]] maps (Figures 1-10) illustrate the possible past distribution of the most characteristic stratigraphic units. These maps are on a [[continental drift]] base modified from the [[http://www.odsn.de/ Ocean Drilling Stratigraphic Network (ODSN)] created in 2005 by the University of Bremen, with Florida occupying a fixed position. In all maps, Cuba is shown in its present position relative to Florida, although different parts of the island came from various places.  

[[Paleogeography|Paleogeographic]] maps (Figures 1-10) illustrate the possible past distribution of the most characteristic stratigraphic units. These maps are on a [[continental drift]] base modified from the [[http://www.odsn.de/ Ocean Drilling Stratigraphic Network (ODSN)] created in 2005 by the University of Bremen, with Florida occupying a fixed position. In all maps, Cuba is shown in its present position relative to Florida, although different parts of the island came from various places.  

In these maps, [[autochthon]]ous nappes, [[allochthon]]ous [[nappe]]s, and [[subduction]] will be used to describe, respectively, the thrusting toward the continent of the sediments, the [[Wikipedia:Basic_rock|basic]] igneous-volcanic rocks, and the subduction. Supported by observations in Cuba and elsewhere, these maps show subduction as the main cause of the uplift of a [http://geology.com/nsta/convergent-plate-boundaries.shtml convergent continental margin] or ocean floor, whereas the nappes are the result of sedimentary or volcanic cover sliding away, under the force of gravity, from the area uplifted by subduction.

In these maps, [[autochthon]]ous nappes, [[allochthon]]ous [[nappe]]s, and [[subduction]] will be used to describe, respectively, the thrusting toward the continent of the sediments, the [[Wikipedia:Basic_rock|basic]] igneous-volcanic rocks, and the subduction. Supported by observations in Cuba and elsewhere, these maps show subduction as the main cause of the uplift of a [http://geology.com/nsta/convergent-plate-boundaries.shtml convergent continental margin] or ocean floor, whereas the nappes are the result of sedimentary or volcanic cover sliding away, under the force of [[gravity]], from the area uplifted by subduction.

Burke,<ref name=Burke_1988>Burke, K., 1988, Tectonic evolution of the Caribbean: Annual Review of Earth and Planetary Sciences, v. 16, p. 201-230.</ref> Pindell and Barrett,<ref name=Pindellandbarrett_1990>Pindell, J. L., and S. F. Barrett, 1990, Geological evolution of the Caribbean region, a plate-tectonic perspective, ''in'' The geology of North America, v. H: The Caribbean region: Geological Society of America, p. 405-432.</ref> Iturralde-Vinent,<ref name=Iturraldevinent_1996>Iturralde-Vinent, M. A., ed., 1996, Ofiolitas y arcos volcanicos de Cuba (Cuban ophiolites and volcanic arcs), ''in'' International Union of Geological Sciences-United Nations Educational, Scientific, and Cultural Organization International Geological Correlation Programe, Contribution 1, Project 364 (Geological correlation of ophiolites and volcanic arc terrane in the Circum-Caribbean realm), 254 p.</ref> Cobiella-Reguera,<ref name=Cobiellareguera_2005>Cobiella-Reguera, J. L., 2005, Emplacement of Cuban ophiolites: Geologica Acta, v. 3, no. 3, p. 273-294.</ref> Garcia-Casco et al.,<ref name=Garciacascoetal_2006>Garcia-Casco, A., R. L. Torres-Roldan, M. A. Iturralde-Vinent, G. Millan, K. Nunez Cambra, C. Lazaro, and A. Rodriguez Vega, 2006, High pressure metamorphism of ophiolites in Cuba: Geologica Acta, v. 4, no. 1-2, p. 63-88.</ref> Giunta et al.,<ref name=Giuntaetal_2006>Giunta, G., L. Beccaluav, and F. Siena, 2006, Caribbean plate margin evolution: constraints and current problems: Geologica Acta, v. 4, no. 102, p. 265-277.</ref> and Pindell et al.<ref name=Pindelletal_2006>Pindell, J. L., L. Kennan, K. P. Stanek, W. V. Maresh, and G. Draper, 2006, Foundations of Gulf of Mexico and Caribbean evolution: Eight controversies resolved: Geologica Acta, v. 4, no. 1-2, p. 303-341.</ref> have interpreted the Cretaceous Cuban subduction as northeast dipping and [http://en.wikipedia.org/wiki/Geomagnetic_reversals reversing polarity] to the southwest during the Late Cretaceous. Cuba's geology suggests that the subduction was continuously north dipping, and this concept is discussed in more detail below.

Burke,<ref name=Burke_1988>Burke, K., 1988, Tectonic evolution of the Caribbean: Annual Review of Earth and Planetary Sciences, v. 16, p. 201-230.</ref> Pindell and Barrett,<ref name=Pindellandbarrett_1990>Pindell, J. L., and S. F. Barrett, 1990, Geological evolution of the Caribbean region, a plate-tectonic perspective, ''in'' The geology of North America, v. H: The Caribbean region: Geological Society of America, p. 405-432.</ref> Iturralde-Vinent,<ref name=Iturraldevinent_1996>Iturralde-Vinent, M. A., ed., 1996, Ofiolitas y arcos volcanicos de Cuba (Cuban ophiolites and volcanic arcs), ''in'' International Union of Geological Sciences-United Nations Educational, Scientific, and Cultural Organization International Geological Correlation Programe, Contribution 1, Project 364 (Geological correlation of ophiolites and volcanic arc terrane in the Circum-Caribbean realm), 254 p.</ref> Cobiella-Reguera,<ref name=Cobiellareguera_2005>Cobiella-Reguera, J. L., 2005, Emplacement of Cuban ophiolites: Geologica Acta, v. 3, no. 3, p. 273-294.</ref> Garcia-Casco et al.,<ref name=Garciacascoetal_2006>Garcia-Casco, A., R. L. Torres-Roldan, M. A. Iturralde-Vinent, G. Millan, K. Nunez Cambra, C. Lazaro, and A. Rodriguez Vega, 2006, High pressure metamorphism of ophiolites in Cuba: Geologica Acta, v. 4, no. 1-2, p. 63-88.</ref> Giunta et al.,<ref name=Giuntaetal_2006>Giunta, G., L. Beccaluav, and F. Siena, 2006, Caribbean plate margin evolution: constraints and current problems: Geologica Acta, v. 4, no. 102, p. 265-277.</ref> and Pindell et al.<ref name=Pindelletal_2006>Pindell, J. L., L. Kennan, K. P. Stanek, W. V. Maresh, and G. Draper, 2006, Foundations of Gulf of Mexico and Caribbean evolution: Eight controversies resolved: Geologica Acta, v. 4, no. 1-2, p. 303-341.</ref> have interpreted the Cretaceous Cuban subduction as northeast dipping and [http://en.wikipedia.org/wiki/Geomagnetic_reversals reversing polarity] to the southwest during the Late Cretaceous. Cuba's geology suggests that the subduction was continuously north dipping, and this concept is discussed in more detail below.

It can also be assumed that, prior to the deposition of the Upper Jurassic rocks, a large area of basement was exposed to the northwest, extending from Florida's Sarasota arch to the Maya Mountains. The nature of this basement is generally unknown, but it must have been of [http://geology.about.com/od/more_igrocks/a/granite.htm granitic] to [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodioritic] composition as indicated by the [[Arkose|arkosic]] nature of the San Cayetano Formation. In south Florida, several wells have penetrated an undifferentiated Jurassic–Triassic volcanic section and Paleozoic granite. The basement must also have included Paleozoic sediments known to outcrop in the Maya Mountains, present as fragments in San Cayetano [[conglomerate]]s, and, perhaps, as exotics in the Cayo Coco Formation. The bulk of the San Cayetano Formation accumulated south of this basement high.

It can also be assumed that, prior to the deposition of the Upper Jurassic rocks, a large area of basement was exposed to the northwest, extending from Florida's Sarasota arch to the Maya Mountains. The nature of this basement is generally unknown, but it must have been of [http://geology.about.com/od/more_igrocks/a/granite.htm granitic] to [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodioritic] composition as indicated by the [[Arkose|arkosic]] nature of the San Cayetano Formation. In south Florida, several wells have penetrated an undifferentiated Jurassic–Triassic volcanic section and Paleozoic granite. The basement must also have included Paleozoic sediments known to outcrop in the Maya Mountains, present as fragments in San Cayetano [[conglomerate]]s, and, perhaps, as exotics in the Cayo Coco Formation. The bulk of the San Cayetano Formation accumulated south of this basement high.

The San Cayetano clastics could have originated from the Gulf of Mexico, as well as nearby South America. As already mentioned, some studies indicate that the southwestern part of the San Cayetano originated from the southwest, and the northeastern part originated from the northeast. Structural complexity makes source direction hard to evaluate.

 

The San Cayetano clastics could have originated from the [[Gulf of Mexico]], as well as nearby South America. As already mentioned, some studies indicate that the southwestern part of the San Cayetano originated from the southwest, and the northeastern part originated from the northeast. Structural complexity makes source direction hard to evaluate.

Toward the northeast, sub-Upper Jurassic sediments have not been observed in situ, but the Cunagua salt suggests the presence of an [[evaporite basin]] correlating with the [[Louann Salt]] and [[Maraval]] [[evaporite]]s and, possibly, as suggested by the San Adrian Formation, interfingering with the San Cayetano.

Toward the northeast, sub-Upper Jurassic sediments have not been observed in situ, but the Cunagua salt suggests the presence of an [[evaporite basin]] correlating with the [[Louann Salt]] and [[Maraval]] [[evaporite]]s and, possibly, as suggested by the San Adrian Formation, interfingering with the San Cayetano.

During the [[Aptian]] (110 Ma; [[:file:St58OverviewFG28.JPG|Figure 4]]), deposition continued to be shallow-water marine along the north coast (Yaguajay* belt) with, farther to the north (Cayo Coco area) and as far as Oriente (Gibara area), some [http://www.merriam-webster.com/dictionary/pelagic pelagic] influence (Casablanca Group). Toward central and western Cuba, conditions continued to be pelagic. The pelagic and shallow-water conditions were separated by a [[Conglomerate|conglomeratic]] [[breccia]] zone (Sagua la Chica* belt) representing a [[forereef]] facies, although reefs themselves are not common in outcrops.

During the [[Aptian]] (110 Ma; [[:file:St58OverviewFG28.JPG|Figure 4]]), deposition continued to be shallow-water marine along the north coast (Yaguajay* belt) with, farther to the north (Cayo Coco area) and as far as Oriente (Gibara area), some [http://www.merriam-webster.com/dictionary/pelagic pelagic] influence (Casablanca Group). Toward central and western Cuba, conditions continued to be pelagic. The pelagic and shallow-water conditions were separated by a [[Conglomerate|conglomeratic]] [[breccia]] zone (Sagua la Chica* belt) representing a [[forereef]] facies, although reefs themselves are not common in outcrops.

There was an influx of quartz- and mica-rich [[Turbidite|turbiditic]] [http://dictionary.reference.com/browse/detrital detritus], possibly from the erosion of the previously formed basement high, which formed the La Esperanza, Polier, and Constancia* Formations. A southern Guajaibon–Sierra Azul carbonate bank may have been deposited.

There was an influx of [[quartz]]- and mica-rich [[Turbidite|turbiditic]] [http://dictionary.reference.com/browse/detrital detritus], possibly from the erosion of the previously formed basement high, which formed the La Esperanza, Polier, and Constancia* Formations. A southern Guajaibon–Sierra Azul carbonate bank may have been deposited.

Toward the south, the close of the Early Cretaceous was characterized by a great outpouring of [http://geology.com/rocks/basalt.shtml basaltic] flows (Matagua* Formation) over rifted basement. This activity was accompanied toward the north and west (Cifuentes*, southern Rosario, northern Rosario, and La Esperanza belts) by abundant and extensive [[chert]] deposits (Calabazar*, Carmita*, and Santa Teresa* Formations).

Toward the south, the close of the Early Cretaceous was characterized by a great outpouring of [http://geology.com/rocks/basalt.shtml basaltic] flows (Matagua* Formation) over rifted basement. This activity was accompanied toward the north and west (Cifuentes*, southern Rosario, northern Rosario, and La Esperanza belts) by abundant and extensive [[chert]] deposits (Calabazar*, Carmita*, and Santa Teresa* Formations).