Early Holocene large-scale meltwater discharge from Greenland documented by foraminifera and sediment parameters

Marit-Solveig Seidenkrantz, Hanne Ebbesen, Steffen Aagaard-Sørensen, Matthias Moros, Jeremy M. Lloyd, Jesper Olsen, Mads Faurschou Knudsen, Antoon Kuijpers

Publikation: Bidrag til tidsskriftArtikelForskningpeer review

35 Citationer (Scopus)

Abstrakt

Records of foraminiferal assemblages combined with lithological properties (grain size, magnetic parameters and XRF data) of marine sediment cores from West Greenland coastal waters and the adjacent Labrador Sea document widespread early Holocene meltwater discharge. This discharge is concluded to originate from large-scale melting of the Greenland Ice Sheet (GIS) having started prior to 8600. cal.yr. BP and ended at about 7700-7500. cal.yr. BP, when the GIS margin had withdrawn from the fjords and become mainly land-based. The benthic foraminiferal record from one of the coastal sites mainly reflects West Greenland Current (WGC) subsurface water properties and to a minor degree surface productivity. The most significant feature in this record is an abrupt shift to a higher-productivity regime around ~. 7700. cal.yr. BP. We suggest that the cessation of a widespread GIS meltwater discharge at that time favoured an increased influence of (sub)surface water of Atlantic origin and initiation of modern subpolar gyre circulation enabling Labrador Sea deep convection. Further offshore, a record of planktonic foraminiferal assemblages shows an oceanographic change at ca. 9500. cal.yr. BP, whilst a gradual but marked change in the planktonic foraminiferal assemblage between 8800 and 7000. cal.yr. BP may be related to a narrowing of the WGC low-salinity surface water belt. The oceanic regime off West Greenland prior to ~. 7800. cal.yr. BP was thus characterised by the presence of a permanent and widespread meltwater surface layer, presumably preventing deep convection in this region. Apart from indications of a slight decrease in meltwater discharge by the benthic foraminiferal fauna data, neither of the records show any clear signal of a regionally important 8.2. ka event.

OriginalsprogEngelsk
Sider (fra-til)71-81
Antal sider11
TidsskriftPalaeogeography, Palaeoclimatology, Palaeoecology
Vol/bind391
Udgave nummerPart A
DOI
StatusUdgivet - 1 dec. 2013

Programområde

  • Programområde 5: Natur og klima

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