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[[File:Calhau.jpg|250px|thumb|Beach on [[São Vicente, Cape Verde|São Vicente Island]].]] |
[[File:Calhau.jpg|250px|thumb|Beach on [[São Vicente, Cape Verde|São Vicente Island]].]] |
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[[Cape Verde]] is a volcanic archipelago situated above an oceanic rise that puts the base of the islands {{convert|2|km|sp=us}} above the rest of the [[seafloor]]. Cape Verde has been identified as a [[hotspot (geology)|hotspot]] and It has been argued that the archipelago may be underlain by a [[mantle plume]] and that the unusual [[geochemistry|geochemical]] signatures of its lavas derive from recycled oceanic [[crust (geology)|crust]] and [[lithosphere]] in the source material.<ref>{{cite journal |last1=Pim |first1=J. |last2=Peirce |first2=C. |last3=Watts |first3=A.B. |last4=Grevemeyer |first4=I. |last5=Krabbenhoeft |first5=A. |date=2008 |title=Crustal structure and origin of the Cape Verde Rise |url=https://www.sciencedirect.com/science/article/pii/S0012821X08003257?casa_token=AeJMMpa8ymoAAAAA:0BQMdUWd8WpGkB4F7v63OKN8iDzoSD3JZS5q4CSCtm87R_02XYIyp5aB9Sk-1-A88EGyCVs#bib2 |journal=Earth and Planetary Science Letters |volume=272 |issue=1-2 |pages=422-428 |doi=10.1016/j.epsl.2008.05.012}}</ref><ref>{{cite journal |last1=Doucelance |first1=R. |last2=Escrig |first2=S. |last3=Moreira |first3=M. |last4=Gariépy |first4=C. |last5=Kurz |first5=M.D. |date=2003 |title=Pb-Sr-He isotope and trace element geochemistry of the Cape Verde Archipelago |url=https://www.sciencedirect.com/science/article/pii/S0016703703001613 |journal=Geochimica et Cosmochimica Acta |volume=67 |issue=19 |pages=3717-3733 |doi= 10.1016/S0016-7037(03)00161-3}}</ref> The lack of any clear age progression in the Cape Verde Archipelago, however, is inconsistent with a mantle plume origin, and various lines of evidence suggest that the islands are a product rather of sub-lithospheric small-scale [[convection]] and instabilities arising from heterogeneities in the [[asthenosphere]] and variations in lithospheric thickness.<ref>{{cite journal |last1=King |first1=S.D. |last2=Ritsema |first2=J. |date=2000 |title=African hot spot volcanism: Small-scale convection in the upper mantle beneath cratons |url=https://science.sciencemag.org/content/290/5494/1137 |journal=Science |volume=290 |issue=5494 |pages=1137-1140 |doi=10.1126/science.290.5494.1137}}</ref><ref>{{cite journal |last1=Kitagawa |first1=H. |last2=Kobayashi |first2=K. |last3=Nakamura |first3=E. |date=2019 |title= Origin of ocean island basalts in the West African passive margin without mantle plume involvement |url=https://www.nature.com/articles/s41467-019-10832-7 |journal=Nature Communications |volume=10 |pages=3022 |doi= 10.1038/s41467-019-10832-7}}</ref><ref>{{cite journal |last1=Foulger |first1=G.R. |last2=Natland |first2=J.H. |date=2003 |title=Is "hotspot" volcanism a consequence of plate tectonics? |url=https://science.sciencemag.org/content/300/5621/921|journal=Science |volume=300 |issue=5621 |pages=921-922 |doi= 10.1126/science.1083376}}</ref><ref>{{cite book |last=Foulger |first=G.R. |editor-last1=Foulger |editor-first1=G.R. |editor-last2=Jurdy |editor-first2=Donna M. |title=Plates, plumes, and planetary processes: Geological Society of America Special Paper 430 |publisher=The Geological Society of America |date=2007 |pages=1-28 |chapter=The ‘plate’ model for the genesis of melting anomalies |isbn=978-0813724300}}</ref><ref>{{cite book |last=Foulger |first= G.R. |date= 2010|title= Plates vs. plumes: A geological controversy |location= Oxford |publisher=Wiley-Blackwell |isbn=978-1-4443-3679-5}}</ref> The geochemistry of the lavas has been explained in terms of remnants of subcontinental lithospheric [[mantle (geology)|mantle]] left in the oceanic lithosphere when the Atlantic Ocean opened.<ref>{{cite journal |last1=Coltorti |first1=M. |last2=Bonadiman |first2=C. |last3=O'Reilly |first3=S.Y. |last4=Griffin |first4=W.L. |last5=Pearson| first5=N.J. |date=2010 |title=Buoyant ancient continental mantle embedded in oceanic lithosphere (Sal Island, Cape Verde Archipelago) |url=https://www.sciencedirect.com/science/article/pii/S0024493709004617 |journal=Lithos |volume=120 |issue=1 |pages=223-233 |doi=10.1016/j.lithos.2009.11.005}}</ref><ref>{{cite web |url=http://www.mantleplumes.org/CapeVerde.html |title=Ancient continental lithospheric mantle beneath oceanic islands – Cape Verde Archipelago |last1=O'Reilly |first1=S.Y.|last2=Coltorti |first2=M. |last3=Bonadiman |first3=C. |last4=Griffin |first4=W.L. |last5=Pearson| first5=N.J. |date=2010 |website=MantlePlumes.org |access-date=28 October 2020}}</ref> |
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[[Cape Verde]] is a volcanic archipelago situated above an oceanic rise that puts the base of the islands {{convert|2|km|sp=us}} above the rest of the [[seafloor]]. Cape Verde has been identified as a [[hotspot (geology)|hotspot]] and it has been argued that a [[mantle plume]] might be underneath it causing the [[volcanic activity]] and associated [[geothermal]] anomalies. |
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Though Cape Verde's islands are all volcanic in origin, they vary widely in terrain.<ref name=pc/> A [[Mount Fogo|still-active volcano on the island of Fogo]] is the highest point on the archipelago (elevation {{convert|2829|m|ft|0|sp=us|disp=or}}).<ref name=pc>[http://www.peacecorps.gov/welcomebooks/cvwb655.pdf ''The Peace Corps Welcomes You to Cape Verde'']. [[Peace Corps]] (April 2006). ''This article incorporates text from this source, which is in the [[public domain]].</ref> Extensive [[Salt pan (geology)|salt flats]] are found on Sal and Maio.<ref name=pc/> On Santiago, Santo Antão, and São Nicolau, arid slopes give way in places to sugarcane fields or banana plantations spread along the base of towering mountains.<ref name=pc/> |
Though Cape Verde's islands are all volcanic in origin, they vary widely in terrain.<ref name=pc/> A [[Mount Fogo|still-active volcano on the island of Fogo]] is the highest point on the archipelago (elevation {{convert|2829|m|ft|0|sp=us|disp=or}}).<ref name=pc>[http://www.peacecorps.gov/welcomebooks/cvwb655.pdf ''The Peace Corps Welcomes You to Cape Verde'']. [[Peace Corps]] (April 2006). ''This article incorporates text from this source, which is in the [[public domain]].</ref> Extensive [[Salt pan (geology)|salt flats]] are found on Sal and Maio.<ref name=pc/> On Santiago, Santo Antão, and São Nicolau, arid slopes give way in places to sugarcane fields or banana plantations spread along the base of towering mountains.<ref name=pc/> |
Revision as of 21:49, 28 October 2020
Cape Verde is a volcanic archipelago situated above an oceanic rise that puts the base of the islands 2 kilometers (1.2 mi) above the rest of the seafloor. Cape Verde has been identified as a hotspot and It has been argued that the archipelago may be underlain by a mantle plume and that the unusual geochemical signatures of its lavas derive from recycled oceanic crust and lithosphere in the source material.[1][2] The lack of any clear age progression in the Cape Verde Archipelago, however, is inconsistent with a mantle plume origin, and various lines of evidence suggest that the islands are a product rather of sub-lithospheric small-scale convection and instabilities arising from heterogeneities in the asthenosphere and variations in lithospheric thickness.[3][4][5][6][7] The geochemistry of the lavas has been explained in terms of remnants of subcontinental lithospheric mantle left in the oceanic lithosphere when the Atlantic Ocean opened.[8][9]
Though Cape Verde's islands are all volcanic in origin, they vary widely in terrain.[10] A still-active volcano on the island of Fogo is the highest point on the archipelago (elevation 2,829 meters or 9,281 feet).[10] Extensive salt flats are found on Sal and Maio.[10] On Santiago, Santo Antão, and São Nicolau, arid slopes give way in places to sugarcane fields or banana plantations spread along the base of towering mountains.[10]
The islands are geologically principally composed of igneous rocks, with basic volcanics and pyroclastics comprising the majority of the total volume. The volcanic and plutonic rocks are distinctly basic in character. The archipelago is an example of a soda-alkaline petrographic province, with a petrologic succession which is similar to that found in other Mid Atlantic islands. Mount Fogo is an active volcano which most recently erupted in 2014. Fogo's caldera is 8 km (5 mi) in diameter, the rim is at an elevation of 1,600 m (5,249 ft) with an interior cone rising to 2,830 m (9,285 ft) from the crater's floor level. Calderas probably result from the subsidence, following the partial evacuation of the magma chamber, of a cylindrical block into the supplying magma chamber, in this case lying at a depth of some 8 km (5 mi). The archipelago has been dated at approximately 180 million years old.[11]
References
- ^ Pim, J.; Peirce, C.; Watts, A.B.; Grevemeyer, I.; Krabbenhoeft, A. (2008). "Crustal structure and origin of the Cape Verde Rise". Earth and Planetary Science Letters. 272 (1–2): 422–428. doi:10.1016/j.epsl.2008.05.012.
- ^ Doucelance, R.; Escrig, S.; Moreira, M.; Gariépy, C.; Kurz, M.D. (2003). "Pb-Sr-He isotope and trace element geochemistry of the Cape Verde Archipelago". Geochimica et Cosmochimica Acta. 67 (19): 3717–3733. doi:10.1016/S0016-7037(03)00161-3.
- ^ King, S.D.; Ritsema, J. (2000). "African hot spot volcanism: Small-scale convection in the upper mantle beneath cratons". Science. 290 (5494): 1137–1140. doi:10.1126/science.290.5494.1137.
- ^ Kitagawa, H.; Kobayashi, K.; Nakamura, E. (2019). "Origin of ocean island basalts in the West African passive margin without mantle plume involvement". Nature Communications. 10: 3022. doi:10.1038/s41467-019-10832-7.
- ^ Foulger, G.R.; Natland, J.H. (2003). "Is "hotspot" volcanism a consequence of plate tectonics?". Science. 300 (5621): 921–922. doi:10.1126/science.1083376.
- ^ Foulger, G.R. (2007). "The 'plate' model for the genesis of melting anomalies". In Foulger, G.R.; Jurdy, Donna M. (eds.). Plates, plumes, and planetary processes: Geological Society of America Special Paper 430. The Geological Society of America. pp. 1–28. ISBN 978-0813724300.
- ^ Foulger, G.R. (2010). Plates vs. plumes: A geological controversy. Oxford: Wiley-Blackwell. ISBN 978-1-4443-3679-5.
- ^ Coltorti, M.; Bonadiman, C.; O'Reilly, S.Y.; Griffin, W.L.; Pearson, N.J. (2010). "Buoyant ancient continental mantle embedded in oceanic lithosphere (Sal Island, Cape Verde Archipelago)". Lithos. 120 (1): 223–233. doi:10.1016/j.lithos.2009.11.005.
- ^ O'Reilly, S.Y.; Coltorti, M.; Bonadiman, C.; Griffin, W.L.; Pearson, N.J. (2010). "Ancient continental lithospheric mantle beneath oceanic islands – Cape Verde Archipelago". MantlePlumes.org. Retrieved 28 October 2020.
- ^ a b c d The Peace Corps Welcomes You to Cape Verde. Peace Corps (April 2006). This article incorporates text from this source, which is in the public domain.
- ^ Mitchell-Thomé, Raoul C. "Outline of the geology of the Cape Verde Archipelago" Geologische Rundschau, Volume 61, Issue 3, pp. 1087–1109