We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Subsurface North Atlantic warming as a trigger of rapid cooling events: evidence from the early Pleistocene (MIS 31-19).
- Authors
Hernández-Almeida, I.; Sierro, F.-J.; Cacho, I.; Flores, J.-A.
- Abstract
Subsurface water column dynamics in the subpolar North Atlantic were reconstructed in order to improve the understanding of the cause of abrupt ice-rafted detritus (IRD) events during cold periods of the early Pleistocene. We used paired Mg/Ca and δ18O measurements of Neogloboquadrina pachyderma (sinistral â€" sin.), deep-dwelling planktonic foraminifera, to estimate the subsurface temperatures and seawater δ18O from a sediment core from Gardar Drift, in the subpolar North Atlantic. Carbon isotopes of benthic and planktonic foraminifera from the same site provide information about the ventilation and water column nutrient gradient. Mg/Ca-based temperatures and seawater δ18O suggest increased subsurface temperatures and salinities during ice-rafting, likely due to northward subsurface transport of subtropical waters during periods of weaker Atlantic Meridional Overturning Circulation (AMOC). Planktonic carbon isotopes support this suggestion, showing coincident increased subsurface ventilation during deposition of IRD. Subsurface accumulation of warm waters would have resulted in basal warming and break-up of ice-shelves, leading to massive iceberg discharges in the North Atlantic. The release of heat stored at the subsurface to the atmosphere would have helped to restart the AMOC. This mechanism is in agreement with modelling and proxy studies that observe a subsurface warming in the North Atlantic in response to AMOC slowdown during Marine Isotope Stage (MIS) 3.
- Subjects
NORTH Atlantic Region; PLEISTOCENE Epoch; NEOGLOBOQUADRINA pachyderma; SEDIMENTS; SURFACE temperature; MERIDIONAL overturning circulation
- Publication
Climate of the Past, 2015, Vol 11, Issue 4, p687
- ISSN
1814-9324
- Publication type
Article
- DOI
10.5194/cp-11-687-2015