Geology edit
The West Indies is a geologically complex island system consisting of 7,000 islands and islets. The West Indies stretches over 3,000 km from the Atlantic Ocean near the Florida peninsula of North America south-southeast across the Caribbean Sea to the northern coast of Venezuela.[1] These islands include active volcanoes, low-lying atolls, raised limestone islands, and large fragments of continental crust containing tall mountains and insular rivers.[2] Geologically, the West Indies consists of three separate archipelagos, each with unique origins and geologic composition.
Greater Antilles edit
The Greater Antilles is geologically the oldest of the three archipelagos and includes both the largest islands (Cuba, Jamaica, Hispaniola, and Puerto Rico) and the tallest mountains (Pico Duarte, Blue Mountain, Pic la Selle, Pico Turquino) in the Caribbean.[3] The islands of the Greater Antilles are composed of strata of different geological ages including Precambrian fragmented remains of the North American Plate (older than 541 million years), Jurassic aged limestone (201.3-145 million years ago), as well as island arc deposits and oceanic crust from the Cretaceous (145-66 million years ago).[4]
The Greater Antilles originated near the Isthmian region of present day Central America in the Late Cretaceous (commonly referred to as the Proto-Antilles), then drifted eastward arriving in their current location when colliding with the Bahama Platform of the North American Plate ca. 56 million years ago in the late Paleocene.[5] This collision caused subduction and volcanism in the Proto-Antillean area and likely resulted in continental uplift of the Bahama Platform and changes in sea level.[6] The Greater Antilles have continuously been exposed since the start of the Paleocene or at least since the Middle Eocene (66-40 million years ago), but which areas were above sea level throughout the history of the islands remains unresolved.[7][5]
The oldest rocks in the Greater Antilles are located in Cuba. They consist of metamorphosed graywacke, argillite, tuff, mafic igneous extrusive flows, and carbonate rock.[8] It is estimated that nearly 70% of Cuba consists of karst limestone.[9] The Blue Mountains of Jamaica are a granite outcrop rising over 2,000 meters, while the rest of the island to the west consists mainly of karst limestone.[9] Much of Hispaniola, Puerto Rico, and the Virgin Islands were formed by the collision of the Caribbean Plate with the North American Plate and consist of 12 island arch terranes.[10] These terranes consist of oceanic crust, volcanic and plutonic rock.[10]
Lesser Antilles edit
The Lesser Antilles is a volcanic island arc rising along the leading edge of the Caribbean Plate due to the subduction of the Atlantic seafloor of the North American and South American plates. The volcanic activity that formed these islands began in the Paleogene, after a period of volcanism in the Greater Antilles ended, and continues today.[6] The main arc of the Lesser Antilles runs north from the coast of Venezuela to the Anegada Passage, a strait separating them from the Greater Antilles, and includes 19 active volcanoes.[11] Major islands of the Lesser Antilles likely emerged less than 20 Ma, during the Miocene.[3]
Lucayan Archipelago edit
The Lucayan Archipelago includes the Bahamas and Turks and Caicos Islands, a chain of barrier reefs and low islands atop the Bahama Platform. The Bahama Platform is a carbonate block formed of marine sediments and fixed to the North American Plate.[2] The emergent islands of the Bahamas and Turks and Caicos likely formed from accumulated deposits of wind-blown sediments during Pleistocene glacial periods of lower sea level.[2]
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References edit
- ^ "West Indies | History, Maps, Facts, & Geography". Encyclopedia Britannica. Retrieved 2019-02-10.
- ^ a b c Ricklefs, Robert; Bermingham, Eldredge (2008). "The West Indies as a laboratory of biogeography and evolution". Philosophical Transactions of the Royal Society B: Biological Sciences. 363 (1502): 2393–2413. doi:10.1098/rstb.2007.2068. PMC 2606802. PMID 17446164.
- ^ a b Woods, C.A. (2001). Biogeography of the West Indies: Patterns and Perspectives. CRC Press. pp. 15–33. ISBN 978-0849320019.
- ^ "Flora of the West Indies".
- ^ a b Graham, Alan (2003). "Geohistory Models and Cenozoic Paleoenvironments of the Caribbean Region". Systematic Botany. 28 (2): 378–386. JSTOR 3094007 – via JSTOR.
- ^ a b Santiago-Valentin, Eugenio; Olmstead, Richard G. (2004). "Historical biogeography of Caribbean plants: introduction to current knowledge and possibilities from a phylogenetic perspective". Taxon. 53 (2): 299–319. doi:10.2307/4135610. ISSN 0040-0262. JSTOR 4135610.
- ^ Iturralde-Vinent, Manuel A. (2006). "Meso-Cenozoic Caribbean Paleogeography: Implications for the Historical Biogeography of the Region". International Geology Review. 48 (9): 791–827. doi:10.2747/0020-6814.48.9.791. S2CID 55392113. Retrieved 2019-02-10.
- ^ Khudoley, K. M.; Meyerhoff, A. A. (1971), "Paleogeography and Geological History of Greater Antilles", Geological Society of America Memoirs, Geological Society of America, pp. 1–192, doi:10.1130/mem129-p1, ISBN 0813711290, retrieved 2019-04-14
- ^ a b geolounge (2012-01-08). "Caribbean Islands: the Greater Antilles". GeoLounge: All Things Geography. Retrieved 2019-04-14.
- ^ a b Mann, Paul; Draper, Grenville; Lewis, John F. (1991), "An overview of the geologic and tectonic development of Hispaniola", Geological Society of America Special Papers, Geological Society of America, pp. 1–28, doi:10.1130/spe262-p1, ISBN 0813722624, retrieved 2019-04-14
- ^ "The University of the West Indies Seismic Research Centre". uwiseismic.com. Retrieved 2019-04-14.