| Title | Regional anomalies of sediment thickness, basement depth and isostatic crustal thickness in the North Atlantic Ocean |
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| Author | Louden, K E; Tucholke, B E; Oakey, G N |
| Source | Earth and Planetary Science Letters vol. 224, issue 1-2, 2004 p. 193-211, https://doi.org/10.1016/j.epsl.2004.05.002 |
| Image |  |
| Year | 2004 |
| Alt Series | Geological Survey of Canada, Contribution Series 2004104 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Northern offshore region; Eastern offshore region |
| Area | North Atlantic Ocean |
| Lat/Long WENS | -70.0000 -1.0000 70.0000 30.0000 |
| Subjects | general geology; marine geology; sedimentology; sediment distribution; sediments; marine sediments; bottom sediments; sediments, volcanogenic; volcanic features; seismic data; submarine features;
oceanic crust; Labrador Sea; Davis Strait; Edoras Bank; Greenland Bank; Azores-Biscay Rise; Milne Seamounts; Newfoundland Ridge; Madeira-Tore Rise |
| Illustrations | location maps; graphs; models; tables |
| Program | Consolidating Canada's Geoscience Knowledge |
| Released | 2004 07 01 |
| Abstract | We calculate the anomalous basement topography for the North Atlantic Ocean from 30° to 70°N latitude and from 0° to 70°W longitude at a resolution of roughly 6×6 km, using grids of total sediment
thickness and observed and predicted sea-floor bathymetry to correct for the effects of isostatic sediment loading and lithospheric age. Plotting this residual topography for various plate reconstructions during opening of the North Atlantic, we
delineate consistent patterns of basement highs related to variations in hotspot-related volcanism. In addition to Iceland and the Azores, we recognize three centers of excess volcanism at the mid-Atlantic ridge: the Milne Seamounts and Azores-Biscay
Rise (~75-40 Ma), the Southeast Newfoundland Ridge and Madeira-Tore Rise (~130-110 Ma), and the East and West Thulean Rises (~60-50 Ma). The duration of volcanic activity ranges from 8 to 10 m.y. (Thulean Rises) to 60 m.y. (Iceland) and thus it
appears that both long- and short-lived hotspots coexist, even in relatively close proximity. In contrast, during the period 110-60 Ma we observe little excess volcanism during either continental breakup or seafloor spreading. We estimate isostatic
crustal thickness from the anomalous basement depths, after first removing dynamic effects created by mantle flow. Maximum thicknesses of volcanic features, from 30 km beneath the Greenland-Iceland-Faeroe ridge to ~15 km beneath the Azores-Biscay
Rise, are broadly consistent with seismic data and predictions of decompression melting. Widths of volcanic features indicate that thickening primarily occurs within 100-200 km of hotspots except along continental margins that rifted at the time of
the hotspot activity (i.e. East Greenland and the Hatton-Rockall Bank). We observe conjugate structures south of Greenland and Edoras Bank, where excess volcanism appears to have extended beyond the margin proper and into oceanic crust. Similar
conjugate features appear in the Labrador Sea south of Davis Strait. Finally, we identify anomalous oceanic regions adjacent to some continental margins, where unusually low values of predicted crustal thickness suggest either additional variations
in plate properties or non-isostatic effects within the mantle. |
| GEOSCAN ID | 215663 |
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