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Architecture of North Atlantic contourite drifts modified by transient circulation of the Icelandic mantle plume


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Authors

Parnell-Turner, R 
White, NJ 
McCave, IN 
Henstock, TJ 
Murton, B 

Abstract

jats:titleAbstract</jats:title>jats:pOverflow of Northern Component Water, the precursor of North Atlantic Deep Water, appears to have varied during Neogene times. It has been suggested that this variation is moderated by transient behavior of the Icelandic mantle plume, which has influenced North Atlantic bathymetry through time. Thus pathways and intensities of bottom currents that control deposition of contourite drifts could be affected by mantle processes. Here, we present regional seismic reflection profiles that cross sedimentary accumulations (Björn, Gardar, Eirik, and Hatton Drifts). Prominent reflections were mapped and calibrated using a combination of boreholes and legacy seismic profiles. Interpreted seismic profiles were used to reconstruct solid sedimentation rates. Björn Drift began to accumulate in late Miocene times. Its average sedimentation rate decreased at ∼2.5 Ma and increased again at ∼0.75 Ma. In contrast, Eirik Drift started to accumulate in early Miocene times. Its average sedimentation rate increased at ∼5.5 Ma and decreased at ∼2.2 Ma. In both cases, there is a good correlation between sedimentation rates, inferred Northern Component Water overflow, and the variation of Icelandic plume temperature independently obtained from the geometry of diachronous V‐shaped ridges. Between 5.5 and 2.5 Ma, the plume cooled, which probably caused subsidence of the Greenland‐Iceland‐Scotland Ridge, allowing drift accumulation to increase. When the plume became hotter at 2.5 Ma, drift accumulation rate fell. We infer that deep‐water current strength is modulated by fluctuating dynamic support of the Greenland‐Scotland Ridge. Our results highlight the potential link between mantle convective processes and ocean circulation.</jats:p>

Description

Keywords

contourite, drift, Iceland, plume

Journal Title

Geochemistry, Geophysics, Geosystems

Conference Name

Journal ISSN

1525-2027
1525-2027

Volume Title

16

Publisher

American Geophysical Union (AGU)
Sponsorship
Natural Environment Research Council (NE/G007632/1)
This work is partly supported by Natural Environment Research Council Grant NE/G007632/1. RPT was supported by the University of Cambridge Girdler Fund and by BP Exploration.