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Cuba: Geologic history (view source)

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file:St58OverviewFG25.JPG|{{figure number|5}}Cuba. 163 Ma: Callovian. PC = Precambrian; PZ = Paleozoic.<ref name=Pardo_2009>Pardo, G., 2009, The geology of Cuba: [http://store.aapg.org/detail.aspx?id=845 AAPG Studies in Geology 58], 73 p.</ref>

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file:St58OverviewFG25.JPG|{{figure number|1}}Cuba. 163 Ma: Callovian. PC = Precambrian; PZ = Paleozoic.<ref name=Pardo_2009>Pardo, G., 2009, The geology of Cuba: [http://store.aapg.org/detail.aspx?id=845 AAPG Studies in Geology 58], 73 p.</ref>

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file:St58OverviewFG26.JPG|{{figure number|6}}Cuba. 144 Ma: early Tithonian.<ref name=Pardo_2009 />

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file:St58OverviewFG26.JPG|{{figure number|2}}Cuba. 144 Ma: early Tithonian.<ref name=Pardo_2009 />

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file:St58OverviewFG27.JPG|{{figure number|7}}Cuba. 132 Ma: Valanginian.<ref name=Pardo_2009 />

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file:St58OverviewFG27.JPG|{{figure number|3}}Cuba. 132 Ma: Valanginian.<ref name=Pardo_2009 />

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file:St58OverviewFG28.JPG|{{figure number|8}}Cuba. 110 Ma: Aptian.<ref name=Pardo_2009 />

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file:St58OverviewFG28.JPG|{{figure number|4}}Cuba. 110 Ma: Aptian.<ref name=Pardo_2009 />

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file:St58OverviewFG29.JPG|{{figure number|9}}Cuba. 94 Ma: Cenomanian.<ref name=Pardo_2009 />

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file:St58OverviewFG29.JPG|{{figure number|5}}Cuba. 94 Ma: Cenomanian.<ref name=Pardo_2009 />

</gallery>

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[[Paleogeography|Paleogeographic]] maps (Figures 5-14) 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.

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[[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.

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file:St58OverviewFG30.JPG|{{figure number|10}}Cuba. 80 Ma: Santonian.<ref name=Pardo_2009 />

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file:St58OverviewFG30.JPG|{{figure number|6}}Cuba. 80 Ma: Santonian.<ref name=Pardo_2009 />

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file:St58OverviewFG31.JPG|{{figure number|11}}Cuba. 67 Ma: Maastrichtian.<ref name=Pardo_2009 />

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file:St58OverviewFG31.JPG|{{figure number|7}}Cuba. 67 Ma: Maastrichtian.<ref name=Pardo_2009 />

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file:St58OverviewFG32.JPG|{{figure number|12}}Cuba. 50 Ma: top lower Eocene.<ref name=Pardo_2009 />

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file:St58OverviewFG32.JPG|{{figure number|8}}Cuba. 50 Ma: top lower Eocene.<ref name=Pardo_2009 />

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file:St58OverviewFG33.JPG|{{figure number|13}}Cuba. 40 Ma: base upper Eocene.<ref name=Pardo_2009 />

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file:St58OverviewFG33.JPG|{{figure number|9}}Cuba. 40 Ma: base upper Eocene.<ref name=Pardo_2009 />

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file:St58OverviewFG34.JPG|{{figure number|14}}Cuba. Present.<ref name=Pardo_2009 />

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file:St58OverviewFG34.JPG|{{figure number|10}}Cuba. Present.<ref name=Pardo_2009 />

</gallery>

===Early(?)-Middle Jurassic===

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Very little is known about the pre-Late Jurassic history of the island except that the lower part of the San Cayetano clastics might be Lower Jurassic (163 Ma; [[:file:St58OverviewFG25.JPG|Figure 5]]). The San Cayetano must have been deposited over an initially [[rift]]ing [[basement]] that probably included fragments of [[continental crust]] as well as [http://geology.com/rocks/basalt.shtml basaltic] flows. This is supported by the sub-Neocomian [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodioritic] [[klippe]]n of La Rana, Tres Guanos, and Rancho Veloz and the occurrences of the El Sabalo and Nueva Maria [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?Term=tholeiite tholeitic basalt]s underlying the sedimentary section of the northern Rosario belt and Cifuentes* belt of the Sierra de Camajan.

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Very little is known about the pre-Late Jurassic history of the island except that the lower part of the San Cayetano clastics might be Lower Jurassic (163 Ma; [[:file:St58OverviewFG25.JPG|Figure 1]]). The San Cayetano must have been deposited over an initially [[rift]]ing [[basement]] that probably included fragments of [[continental crust]] as well as [http://geology.com/rocks/basalt.shtml basaltic] flows. This is supported by the sub-Neocomian [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodioritic] [[klippe]]n of La Rana, Tres Guanos, and Rancho Veloz and the occurrences of the El Sabalo and Nueva Maria [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?Term=tholeiite tholeitic basalt]s underlying the sedimentary section of the northern Rosario belt and Cifuentes* belt of the Sierra de Camajan.

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.

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===Tithonian===

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In the [[Tithonian]] (144 Ma; [[:file:St58OverviewFG26.JPG|Figure 6]]) section, sediments vary from the shallow-water carbonate and evaporite deposits of Wood River, Punta Alegre*, and Guani* in the north, toward Florida and the Bahamas, to shallow-water normal marine limestones of the [[Trocha Group|Trocha* Group]] to the south in the Las Villas* belt. Toward Pinar del Rio, thick, massive, shallow-water limestone of the [[Guasasa Formation]] accumulated over a northward-thinning wedge of San Cayetano, [[Jagua]], and possibly, basement. Farther south, the thin-bedded limestones of Cobrito, Sauco, and Isla de la Juventud marbles were deposited over the lower [[Oxfordian]] thin quartzose sandstones of [[La Lamagua Formation|La Llamagua]], [[Loma la Gloria Formation|Loma la Gloria]], and [[Agua Santa Formation]]s. The outpouring of [http://geology.com/rocks/basalt.shtml basalt] continued forming the slightly younger [[Nueva Maria Formation]] in the southern Loma Camajan. Farther south, rifting produced [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasic] [[oceanic crust]].

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In the [[Tithonian]] (144 Ma; [[:file:St58OverviewFG26.JPG|Figure 2]]) section, sediments vary from the shallow-water carbonate and evaporite deposits of Wood River, Punta Alegre*, and Guani* in the north, toward Florida and the Bahamas, to shallow-water normal marine limestones of the [[Trocha Group|Trocha* Group]] to the south in the Las Villas* belt. Toward Pinar del Rio, thick, massive, shallow-water limestone of the [[Guasasa Formation]] accumulated over a northward-thinning wedge of San Cayetano, [[Jagua]], and possibly, basement. Farther south, the thin-bedded limestones of Cobrito, Sauco, and Isla de la Juventud marbles were deposited over the lower [[Oxfordian]] thin quartzose sandstones of [[La Lamagua Formation|La Llamagua]], [[Loma la Gloria Formation|Loma la Gloria]], and [[Agua Santa Formation]]s. The outpouring of [http://geology.com/rocks/basalt.shtml basalt] continued forming the slightly younger [[Nueva Maria Formation]] in the southern Loma Camajan. Farther south, rifting produced [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasic] [[oceanic crust]].

===Neocomian===

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Shallow-water platform carbonates, with some evaporites, continued to accumulate in the north (coastal area, [[Yaguajay belt|Yaguajay* belt]]). Elsewhere in central and western Cuba ([[Las Villas belt|Las Villas*]], southern [[Rosario belt]]s), the water was markedly deeper as indicated by the deposition of the [[Capitolio Formation|Capitolio*]] and [[Artemisa Formation]]s containing abundant [[nannoplankton]] (commonly rock forming) and other [http://www.merriam-webster.com/dictionary/pelagic pelagic] forms.

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Some tectonic activity extended into the [[Neocomian]] (132 Ma~~; see Figure 27~~), possibly associated with the rifting, and uplifted blocks south of the Yaguajay* belt. The result was denudation of previously deposited sediments as indicated by northward shedding of carbonate clastics ([[Sabanilla Fromation|Sabanilla* Formation]]), a southward increase in basement exposures (La Rana, Tres Guanos, Rancho Veloz), and deposition of the [[Jobosi]]* [[Arkose|arkosic]] [[conglomerate]]. This basement could have been derived from a continental block, here named the La Rana block (after the best exposures) and similar to the Maya or Chortis blocks, that was overridden by later nappes.

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Some tectonic activity extended into the [[Neocomian]] (132 Ma), possibly associated with the rifting, and uplifted blocks south of the Yaguajay* belt. The result was denudation of previously deposited sediments as indicated by northward shedding of carbonate clastics ([[Sabanilla Fromation|Sabanilla* Formation]]), a southward increase in basement exposures (La Rana, Tres Guanos, Rancho Veloz), and deposition of the [[Jobosi]]* [[Arkose|arkosic]] [[conglomerate]]. This basement could have been derived from a continental block, here named the La Rana block (after the best exposures) and similar to the Maya or Chortis blocks, that was overridden by later nappes.

In central Cuba, the Upper Jurassic and Neocomian beds were only partially eroded. In western Cuba, shallow-bank carbonates, similar to those of the [[Vinas Group|Vinas* Group]], accumulated atop the La Rana [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodiorite] [http://en.wikipedia.org/wiki/Horst_%28geology%29 horst] and formed the Guajaibon–Sierra Azul belt. South of the La Rana basement horst, deep-water limestones of the Mayari, Collantes, and Cobrito Formations were deposited and preserved.

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===Aptian===

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During the [[Aptian]] (110 Ma; [[:file:St58OverviewFG28.JPG|Figure 8]]), 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.

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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.

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===Albian-Cenomanian===

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Except for the Yaguajay* belt along the north coast where platform carbonates accumulated, deep-water [http://www.merriam-webster.com/dictionary/pelagic pelagic] deposition continued during the [[Albian]] to [[Cenomanian]] (93 Ma; [[:file:St58OverviewFG29.JPG|Figure 9]]). In the south, volcanic activity contributed silica to the seawater, which led to the deposition of primary radiolarian [[chert]]s (Calabazar*, Carmita, and Santa Teresa) below the carbonate compensation depth. Whereas noncalcareous [http://dictionary.reference.com/browse/detrital detritus] was absent over most of the northern area, volcanic-derived clays became increasingly abundant toward the south (Santa Teresa* Formation). The Rana [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodiorite] high was still active, providing material for the Chaco Azul Formation. The position of the Vinas* type carbonates of the Guajaibon–Sierra Azul belt is problematic.

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Except for the Yaguajay* belt along the north coast where platform carbonates accumulated, deep-water [http://www.merriam-webster.com/dictionary/pelagic pelagic] deposition continued during the [[Albian]] to [[Cenomanian]] (93 Ma; [[:file:St58OverviewFG29.JPG|Figure 5]]). In the south, volcanic activity contributed silica to the seawater, which led to the deposition of primary radiolarian [[chert]]s (Calabazar*, Carmita, and Santa Teresa) below the carbonate compensation depth. Whereas noncalcareous [http://dictionary.reference.com/browse/detrital detritus] was absent over most of the northern area, volcanic-derived clays became increasingly abundant toward the south (Santa Teresa* Formation). The Rana [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodiorite] high was still active, providing material for the Chaco Azul Formation. The position of the Vinas* type carbonates of the Guajaibon–Sierra Azul belt is problematic.

To the north, as during the Aptian–Albian, the shallow carbonate banks continued to be separated from the pelagic, deep-water sediments to the south by a zone of carbonate-derived clastics, which shifted progressively southward; carbonate [[turbidite]]s became increasingly abundant (Calabazar* and Mata* formations). In the Florida Straits, carbonate deposition did not keep up with subsidence as indicated by the increase in pelagic deposits, including [[chert]] (upper Casablanca Group).

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===Turonian-Campanian===

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[[Turonian]] and [[Coniacian]] rocks are not common across most of the nonvolcanic area (80 Ma; [[:file:St58OverviewFG30.JPG|Figure 10]]). They are present to the north in the Cayo Coco area, to the south in the Seibabo area in central Cuba, and in a few units of the southern and northern Rosario belts in western Cuba. The [[strata]] above and below the missing interval all have deep-water characteristics, and no evidence of subaerial [[erosion]] exists to explain the lack of the Turonian and Coniacian sediments across such a large area. Either there was no deposition, or the section was eroded because of changes in current patterns or [[submarine slide]]s. Local erosion is unlikely because a [[hiatus]] of the same age has been found in many of the holes drilled by the [http://www.deepseadrilling.org/ Deep Sea Drilling Project (DSDP)] in the southern Gulf of Mexico and the western Atlantic. Toward the north, in the platform to deep-water province, whatever sediments remain show that sedimentation continued under [http://www.merriam-webster.com/dictionary/pelagic pelagic] conditions and was essentially calcareous, with subordinate [[chert]]s.

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[[Turonian]] and [[Coniacian]] rocks are not common across most of the nonvolcanic area (80 Ma; [[:file:St58OverviewFG30.JPG|Figure 6]]). They are present to the north in the Cayo Coco area, to the south in the Seibabo area in central Cuba, and in a few units of the southern and northern Rosario belts in western Cuba. The [[strata]] above and below the missing interval all have deep-water characteristics, and no evidence of subaerial [[erosion]] exists to explain the lack of the Turonian and Coniacian sediments across such a large area. Either there was no deposition, or the section was eroded because of changes in current patterns or [[submarine slide]]s. Local erosion is unlikely because a [[hiatus]] of the same age has been found in many of the holes drilled by the [http://www.deepseadrilling.org/ Deep Sea Drilling Project (DSDP)] in the southern Gulf of Mexico and the western Atlantic. Toward the north, in the platform to deep-water province, whatever sediments remain show that sedimentation continued under [http://www.merriam-webster.com/dictionary/pelagic pelagic] conditions and was essentially calcareous, with subordinate [[chert]]s.

Toward the south in the [[Wikipedia:Basic_rock|basic]] igneous-volcanic province, conditions were also dominantly pelagic. Sedimentation was accompanied by a renewal of volcanism, with an outpouring of flows and other [[Wikipedia:Ejecta|ejecta]] of a more [http://geology.about.com/od/rocks/ig/igrockindex/rocpicrhyolite.htm rhyolitic] composition (Pastora* Group). Evidence of subaerial volcanism (such as glass bombs and ash beds) exists. Shallow-water [[reef]]s with [[rudist]]s, [[coral]]s, and large [[foraminifera]] are commonly associated with the volcanics and volcaniclastics. This was the period of major [http://geology.about.com/library/bl/blnutshell_subducfactory.htm arc volcanism] associated with subduction. It was also the time of [http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3598.html intrusion] of the Manicaragua [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000073 granodiorite] into the central Cuba volcanics.

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===Campanian-Maastrichtian===

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After the period of the [[Unconformity|disconformity]], [http://www.merriam-webster.com/dictionary/pelagic pelagic] conditions characterized the platform to deep-water province, which received massive, dominantly carbonate [[turbidite]] flows from the north (Lutgarda* Formation) and from the south (Amaro* and Cacarajicara formations) (67 Ma; [[:file:St58OverviewFG31.JPG|Figure 11]]). Over the [[Wikipedia:Basic_rock|basic]] igneous-volcanic province, local [http://encyclopedia2.thefreedictionary.com/provenance provenance] resulted in an abundance of fragmental rocks; that is, limestones toward the north (Penalver Formation) and volcanics toward the south. In the south, sedimentation was accompanied during the Maastrichtian by an outpouring of late [[Orogeny|orogenic]] [http://geology.com/rocks/basalt.shtml basaltic] flows and flow breccias (the Maastrichtian age of these flows disagrees with the current interpretation of most Cuban geologists, including Iturralde-Vinent, 1996). Toward the north, along the present outer line of clays, deposition of coarse [[Maastrichtian]] limestone [[conglomerate]] (Mayajigua* Formation) graded into fine-grained pelagic rocks. The basic igneous-volcanic province began its initial northward movement as indicated by [http://www.galleries.com/serpentine serpentine] [http://dictionary.reference.com/browse/detrital detritus] in the turbidites, by basic [http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3598.html intrusive]-derived clastics (Miguel Formation) associated with the Domingo* thrust, as well as by the presence of large Maastrichtian [[Thrust fault|thrust]] sheets of [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasics] in Oriente. Thrusting (and metamorphism) of ultrabasics began in the Escambray, and thrust sheets began to stack into the former basin that is today represented by the Guaniguanico Mountains. Northward-[[dip]]ping subduction to the south produced uplift of the [http://geology.com/nsta/convergent-plate-boundaries.shtml convergent margins]. The northward-moving thrust sheets or [[nappe]]s formed as the result of the sedimentary or volcanic cover sliding away from the uplifted areas.

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After the period of the [[Unconformity|disconformity]], [http://www.merriam-webster.com/dictionary/pelagic pelagic] conditions characterized the platform to deep-water province, which received massive, dominantly carbonate [[turbidite]] flows from the north (Lutgarda* Formation) and from the south (Amaro* and Cacarajicara formations) (67 Ma; [[:file:St58OverviewFG31.JPG|Figure 7]]). Over the [[Wikipedia:Basic_rock|basic]] igneous-volcanic province, local [http://encyclopedia2.thefreedictionary.com/provenance provenance] resulted in an abundance of fragmental rocks; that is, limestones toward the north (Penalver Formation) and volcanics toward the south. In the south, sedimentation was accompanied during the Maastrichtian by an outpouring of late [[Orogeny|orogenic]] [http://geology.com/rocks/basalt.shtml basaltic] flows and flow breccias (the Maastrichtian age of these flows disagrees with the current interpretation of most Cuban geologists, including Iturralde-Vinent, 1996). Toward the north, along the present outer line of clays, deposition of coarse [[Maastrichtian]] limestone [[conglomerate]] (Mayajigua* Formation) graded into fine-grained pelagic rocks. The basic igneous-volcanic province began its initial northward movement as indicated by [http://www.galleries.com/serpentine serpentine] [http://dictionary.reference.com/browse/detrital detritus] in the turbidites, by basic [http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3598.html intrusive]-derived clastics (Miguel Formation) associated with the Domingo* thrust, as well as by the presence of large Maastrichtian [[Thrust fault|thrust]] sheets of [https://wwwf.imperial.ac.uk/earthscienceandengineering/rocklibrary/viewglossrecord.php?gID=00000000012 ultrabasics] in Oriente. Thrusting (and metamorphism) of ultrabasics began in the Escambray, and thrust sheets began to stack into the former basin that is today represented by the Guaniguanico Mountains. Northward-[[dip]]ping subduction to the south produced uplift of the [http://geology.com/nsta/convergent-plate-boundaries.shtml convergent margins]. The northward-moving thrust sheets or [[nappe]]s formed as the result of the sedimentary or volcanic cover sliding away from the uplifted areas.

===Paleocene (Danian)===

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===Early to Middle Eocene===

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The early to middle [[Eocene]] was characterized by intense [[Orogeny|orogenic]] activity (50 Ma; [[:file:St58OverviewFG32.JPG|Figure 12]]). Early in the Eocene, the large-scale low-angle [[Thrust fault|thrust sheets]], or gravity [[nappe]]s, that first moved in the Maastrichtian began to move at a greater rate. The volcanic section, along with the [[Oceanic crust|oceanic basement]], rode over the platform to deep water province, probably along the line separating the [[Wikipedia:Basic_rock|basic]] igneous-volcanic province from the platform to deep basin province. As thrusting proceeded, additional thrusts formed within the carbonate section in front of and north of the basic igneous-volcanic front. As a result, the thrust sheets were generally arranged from older and more southerly sourced at the top of the stack to younger and more northerly sourced at the base.

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The early to middle [[Eocene]] was characterized by intense [[Orogeny|orogenic]] activity (50 Ma; [[:file:St58OverviewFG32.JPG|Figure 8]]). Early in the Eocene, the large-scale low-angle [[Thrust fault|thrust sheets]], or gravity [[nappe]]s, that first moved in the Maastrichtian began to move at a greater rate. The volcanic section, along with the [[Oceanic crust|oceanic basement]], rode over the platform to deep water province, probably along the line separating the [[Wikipedia:Basic_rock|basic]] igneous-volcanic province from the platform to deep basin province. As thrusting proceeded, additional thrusts formed within the carbonate section in front of and north of the basic igneous-volcanic front. As a result, the thrust sheets were generally arranged from older and more southerly sourced at the top of the stack to younger and more northerly sourced at the base.

A large trough-shaped basin formed in front of the thrust sheets, deeper near the thrust front and shallower northward. Early to middle Eocene [[flysch]] deposition in the trough began with sediments derived from limestones, such as the Sagua* and San Martin* formations, followed by an increase in volcanic and [http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3598.html intrusive]-derived [http://dictionary.reference.com/browse/detrital detritus], such as the lower Vega* and lower Manacas (Pica Pica) formations, and finally, capped by the intrusive and volcanic-derived coarse [[conglomerate]]s and [http://www.encyclopedia.com/doc/1O13-wildflysch.html wildflysch] of the upper Vega* (Rosas*) and upper Manacas (Vieja) Formations. In central Cuba, the rocks of the deep-water Vega* Formation became coarser grained through time. In western Cuba, the fine-grained clastics and other [http://www.merriam-webster.com/dictionary/pelagic pelagic] sediments of the Manacas Formation changed abruptly to the coarse [[breccia]]s of the Vieja Member. The breccia clasts reflect the lithology of the associated fault blocks. This suggests some subaerial [[erosion]] in central Cuba, whereas western Cuba was largely submarine.

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As the thrust sheets advanced, they overrode the lower to middle Eocene flysch, which had accumulated in front of them, and the flysch served as a lubricating medium for further thrusting. The [[subduction]] responsible for the uplift driving the thrusting ceased progressively from west to east, and volcanic activity continued in Oriente until the middle Eocene. Along what appears to be a north-[[dip]]ping subduction zone and south of the Jardines de la Reina Cays (Camaguey trench) is a filled trench, which is a remnant of an accretionary prism. This trench could be related to the exposures in Haiti's southern peninsula and the Muertos Trench.

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In central and eastern Cuba, the thrust front advanced until the volcanic and basic intrusive rocks covered extensive areas of the massive shallow-water carbonates of the northern coast of the island (Yaguajay* belt, coastal and Gibara areas). After the front stopped advancing, compression from the south continued, tightly folding and then [[reverse fault]]ing the succession of thrust plates. The result was the late Eocene structures shown in [[:file:St58OverviewFG33.JPG|Figure 13]]. As compression continued, the folds became sharper, and the faults began lateral motion, probably because the northward compression was not directed perpendicular to the front of the carbonate banks. It is possible that a deep-seated, crustal [[Strike-slip fault|transcurrent]] fault was also involved.

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In central and eastern Cuba, the thrust front advanced until the volcanic and basic intrusive rocks covered extensive areas of the massive shallow-water carbonates of the northern coast of the island (Yaguajay* belt, coastal and Gibara areas). After the front stopped advancing, compression from the south continued, tightly folding and then [[reverse fault]]ing the succession of thrust plates. The result was the late Eocene structures shown in [[:file:St58OverviewFG33.JPG|Figure 9]]. As compression continued, the folds became sharper, and the faults began lateral motion, probably because the northward compression was not directed perpendicular to the front of the carbonate banks. It is possible that a deep-seated, crustal [[Strike-slip fault|transcurrent]] fault was also involved.

In western Cuba, the northward-moving stack of thrust sheets did not reach the buttress of the Bahamas Platform, and the nappes came to rest on the sea floor toward the southern Gulf of Mexico. As a result, they are less deformed than they are to the east.

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===Late Eocene to Present===

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Shallow-marine conditions prevailed during most of this time interval, and mostly [[Carbonate|limestones]], [[Carbonate|marls]], and [[shale]]s accumulated, accompanied by some coarse [[Lithofacies and environmental analysis of clastic depositional systems|clastic sediment]] (present; [[:file:St58OverviewFG34.JPG|Figure 14]]). There was very little tectonic activity. In the northern basins, a strong angular [[unconformity]] separates the upper Eocene strata from the older rocks. In the southern basins, sedimentation was essentially continuous from the [[Cretaceous]] through the [[Tertiary]], with no major unconformity. Some local basins may have formed as gentle deformation of the old [[Orogeny|orogenic belt]] occurred. This deformation consisted mostly of large-scale folds (Habana-Matanzas) and high-angle [[fault]]s (Pinar). This type of deformation is still active today and is largely responsible for Cuba's present physiography.

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Shallow-marine conditions prevailed during most of this time interval, and mostly [[Carbonate|limestones]], [[Carbonate|marls]], and [[shale]]s accumulated, accompanied by some coarse [[Lithofacies and environmental analysis of clastic depositional systems|clastic sediment]] (present; [[:file:St58OverviewFG34.JPG|Figure 10]]). There was very little tectonic activity. In the northern basins, a strong angular [[unconformity]] separates the upper Eocene strata from the older rocks. In the southern basins, sedimentation was essentially continuous from the [[Cretaceous]] through the [[Tertiary]], with no major unconformity. Some local basins may have formed as gentle deformation of the old [[Orogeny|orogenic belt]] occurred. This deformation consisted mostly of large-scale folds (Habana-Matanzas) and high-angle [[fault]]s (Pinar). This type of deformation is still active today and is largely responsible for Cuba's present physiography.

Cuba is an example of [[subduction]] generating an orogenic belt. The subduction progressed from an oceanic environment through a region of relatively recent [[oceanic crust]] between North and South America and, finally, became inactive at the southern margin of the North American continent. The main difference relative to most of the well-known marginal orogenic belts is that the [[Thrust fault|thrust]] sheets that accompanied the subduction rode onto and over a much depressed and fragmented [[continental margin]] (with fragments now in the Bahamas Basin, Gulf of Mexico, Yucatan) relatively far away from a fully continental craton.

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Cuba: Geologic history (view source)

Revision as of 16:41, 5 January 2015

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