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Book Chapter

Sediment Redistribution on the Reykjanes Ridge: Seismic Evidence

By
W. F. Ruddiman
W. F. Ruddiman
US. North Oceographic Office, Chesapeake Beach Maryland 20732
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Published:
January 01, 1976

Abstract

East-wed seismic reflection lines obtained at 14-km intervals on the eastern flank of the Reykjanes Ridge reveal patterns of sediment cover controlled by the reaction of bottom- water movement to crustal topography. Bot-tom currents have piled sediment into'drifts 3? a variety of scales. The largest of these is Gardar Drift, vyhich is constructed along fragmented basement ridge roughly 42 m.y. iril age. Basement peaks with scoured and moated sedimentary envelopes, outcropping sedimentary strata, and dune topography indicate prej valent erosion and redeposition of bottom sediments. No conformable pelagic draping is anywhere visible in the surveyed vea. Two prominent sediment reflectors occur on crust as young as 17 m.yjand 37 m.y., which sets a maximum limit qp their ages. The younger reflector is highly variable in apparent reflectivity; it is well developed in fracture zones but is indistinct or absent on high-standing crustal blocks of equivalent age between fracture zones. The basement expression of these fracture zones is 12 to 45 m.y. in age ami has been virtually smothered'-by the thickest sediment cover (1.75 km) observed in the survey area.. Part of the fracture zone Ailing appears to be sediment redistributed by bottom currents, but the increased sediment smoothness and re-flectivity in the fractures suggest localized turbid downslope flow within the ridge flank.

In the last 5 to 10 m.y., coarse basaltic sand mainly from Iceland (at 64° N.) has been spread across a broad trough-contained fan southwest of the Iceland-Faeroes Ridge. At 58° N., the turbidite flow is funneled into Maury Channel, ultimately to be spread out onto the Biscay Abyssal Plain at and below 48° N., 1,600 km to the south.

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Mid-Atlantic Ridge

Peter A. Rona
Peter A. Rona
National Oceanic and Atmospheric Administration Atlantic Oceanographic and Meteorological Laboratories 15 Rickenbacker Causeway Miami, Florida 33149
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Geological Society of America
Volume
5
ISBN electronic:
9780813759050
Publication date:
January 01, 1976

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