Architecture of North Atlantic contourite drifts modified by transient circulation of the Icelandic mantle plume. (15th October 2015)

• Record Type: Journal Article
• Authors: Parnell‐Turner, Ross; White, Nicholas J.; McCave, I. Nick; Henstock, Timothy J.; Murton, Bramley; Jones, Stephen M.
• Is Part Of: Geochemistry, geophysics, geosystems. Volume 16:Number 10(2015:Oct.)
• Page Start: 3414
• Page End: 3435
• Publication Date: 2015-10-15
• Subjects: contourite -- drift -- Iceland -- plume; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 550.5
• DOI: 10.1002/2015GC005947
• Languages: English
• ISSNs: 1525-2027

Abstract

Abstract: Overflow 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. Key Points: Seismic reflection profiles of contourite drifts in North Atlantic Ocean Sedimentary accumulation rate of drift deposits varies with time Dynamic support from Iceland plume controls deep‐water flow and drift evolution