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| Detailed Reference Information |
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Klingelhoefer, F., Minshull, T.A., Blackman, D.K., Harben, P. and Childers, V. (2001). Crustal structure of Ascension Island from wide-angle seismic data; implications for the formation of near-ridge volcanic islands. Earth and Planetary Science Letters 190(1-2): 41-56. |
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The study of the internal structure of volcanic islands is important for understanding how such islands form and how the lithosphere deforms beneath them. Studies to date have focused on very large volcanic edifices (e.g., Hawaiian Islands, Marquesas), but less attention has been paid to smaller islands, which are more common. Ascension Island, a 4-km high volcanic edifice with a basal diameter of 60 km, is located in the equatorial Atlantic (8 degrees S), 90 km west of the Mid-Atlantic Ridge on 7 Ma oceanic lithosphere. We present results of a wide-angle seismic profile crossing the island revealing a crustal thickness of 12-13 km, an overthickened layer 3 (7 km thick) and little evidence of lithospheric flexure. Together these results suggest Ascension Island may be older than previously assumed and may have begun forming at an on-axis position around 6-7 Ma. This hypothesis is further supported by the presence of a young 1.4-km high edifice directly adjacent to the Mid-Atlantic Ridge with a volume about 1/7 that of Ascension Island, possibly representing the earliest stages of seamount formation. Excess magmatism appears to be related to the tectonic setting at the ridge-fracture zone intersection. |
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| BACKGROUND DATA FILES |
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Seismic Data |
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The Velocity Model |
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The Velocity Model (continued) |
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Gravity Modelling |
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Keywords
Ascension Island, Atlantic Ocean, Atlantic Ocean Islands, crust, flexure, fracture zones, geophysical methods, geophysical profiles, geophysical surveys, hydrophones, islands, lithosphere, magmatism, Mid-Atlantic Ridge, mid-ocean ridges, ocean floors, oceanic crust, oceanic lithosphere, refraction methods, seismic methods, seismic, profiles, submarine volcanoes, surveys, thickness, velocity structure, volcanism, volcanoes, 18 Solid-earth geophysics, 20 Applied geophysics |
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Publisher
Elsevier Science
P.O. Box 211
1000 AE Amsterdam
The Netherlands
(+31) 20 485 3757
(+31) 20 485 3432
nlinfo-f@elsevier.com |
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