Evolution of oceanic crust on the Kolbeinsey Ridge, north of Iceland, over the past 22 Myr |
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| Authors: | Kodaira Mjelde Gunnarsson Shiobara & Shimamura |
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| Institution: | Institute of Solid Earth Physics, University of Bergen, Allégt. 41, 5007 Bergen, Norway; Institute of Solid Earth Physics, University of Bergen, Allégt. 41, 5007 Bergen, Norway; National Energy Authority, Grensasvergu 9, 108, Reykjavik, Iceland; Lab. Ocean Bottom Seismology, Hokkaido University, N10 W8 Kita-ku Sapporo 060, Japan; Lab. Ocean Bottom Seismology, Hokkaido University, N10 W8 Kita-ku Sapporo 060, Japan |
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| Abstract: | The evolution of oceanic crust on the Kolbeinsey Ridge, north of Iceland, is discussed on the basis of a crustal transect obtained by seismic experiment from the Kolbeinsey Ridge to the Jan Mayen Basin. The crustal model indicates a relatively uniform structure; no significant lateral velocity variations are observed, especially in the lower crust. The uniform velocity structure suggests that the postulated extinct axis does not exist over the oceanic crust formed at the Kolbeinsey Ridge, but supports a model of continuous spreading along the ridge after oceanic spreading started west of the Jan Mayen Basin. The oceanic crust formed at Kolbeinsey Ridge is 1–2.5 km thicker than normal oceanic crust due to hotter-than-normal mantle from the Iceland Mantle Plume. The observed generally uniform thickness throughout the transect might also indicate that the temperatures of the astheno-spheric mantle ascending along the Kolbeinsey Ridge have not changed significantly since the age of magnetic anomaly 6B. |
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