Seamounts in the east of South Atlantic: Origin and correlation with Mesozoic-Cenozoic magmatic structures of West Africa |
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Authors: | A A Peyve |
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Institution: | (1) Geology & Geophysics NSRD, National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK;(2) Present address: Department of Earth Science & Engineering, Imperial College, Prince Consort Road, London, SW7 2BP, UK;(3) IfM-Geomar, Leibniz Institute for Marine Sciences, Kiel, Germany |
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Abstract: | The Mesozoic and Cenozoic seamounts and submarine ridges in the east of the South Atlantic are considered and compared with
the coeval tectonomagmatic structures of West Africa. The conclusion is drawn that within-plate magmatism of the Atlantic
is a waning process related to the ascent of several large plumes beneath West Africa beginning from the Triassic and subsequent
lateral spreading of their material. It is shown that the heated plume material can spread beneath the lithosphere for a great
distance, mixing in various proportions with asthenospheric matter, forming melts variable in geochemistry and isotopic characteristics.
Cooling of the material takes many tens of years with retention of small magma sources episodically supplying melts to the
surface. Localization of permeable zones in the lithosphere, along which the melts ascend, is determined by global stress
fields responsible for the formation of long-lived linear tectonic elements on continents, inherited by young oceanic tectonic
lines. |
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Keywords: | |
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