The origin of Bahia seamounts (Brazil Basin,South Atlantic) in connection to new data on their age |
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Authors: | S G Skolotnev M E Bylinskaya L A Golovina I S Ipat’eva |
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Institution: | 1.Geological Institute,Russian Academy of Sciences,Moscow,Russia |
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Abstract: | Micropalentological studies of limestones and isotopic-geochronological determinations of the age of zircons found in vulcanites
dredged from the region of the northern chain of the group of Bahia seamounts in the 28th cruise of the R/V Akademik Vavilov were undertaken. The recognized age difference of the northern chain of the Bahia seamounts of northwestern strike from 75
to 84 Ma from the southeast to the northwest indicates the fact that this chain was formed as a result of hot spot activity.
The age of vulcanites is in good correlation with the Maastricht and Coniacian-Santonian age of limestones occurring on the
slopes of the seamounts. The similarity of the seamounts age and the age of the oceanic bottom indicates the fact that the
hot spot was localized near the spreading axial zone of the MAR. Along the strike of the chain, the centers of volcanic activity
are correlated to the zones of transform faults, which are important in the hot spot activation. The formed chain is a weak
zone in the lithosphere and the focus of younger stages of volcanic activity; there were at least two of stages within the
northern chain of the Bahia seamounts, and these occurred about 75 and 59 Ma ago. |
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