K-Ar ages from the eastern Azores group (Santa Maria,São Miguel and the Formigas Islands) |
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| Authors: | AA Abdel-Monem LA Fernandez GM Boone |
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| Institution: | 1. Lamont-Doherty Geological Observatory of Columbia University, Palisades, N.Y. 10964 USA;2. Department of Geology, Syracuse University, Syracuse, N.Y. 13210 USA;3. Department of Geology, Syracuse University, Syracuse, N.Y. 13210 USA |
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| Abstract: | Present estimates of the age of volcanic activity in the eastern Azores group are based on shelly fauna in a coquina zone separating the two basaltic sequences on Santa Maria. A Vindobonian (Middle Miocene) age has been assigned to the coquina zone. Our K-Ar data suggests that it was deposited 4–6 m.y. ago, i.e. Mio-Pliocene in age.The basaltic series exposed below the coquina zone on Santa Maria is 6–8 m.y. old and probably much older. The post-coquina basaltic complex is 4 m.y. old and younger. The Nordeste basaltic complex in the NE part of São Miguel and the basaltic flows of the Formigas Bank are also 4 m.y. old and younger. We suggest that the three latter basaltic sequences are chronostratigraphic equivalents. |
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