Comparing MIS3 millennial scale variability in the Gulf Stream area to the GRIP temperature record

Author(s): Vautravers, Maryline J.; Shackleton, Nicholas J.; Gruetzner, Jens; Lopez-Martinez, Constancia; Grimalt, Joan
Author Affiliation(s): Primary:
Cambridge University, Godwin Laboratory for Quaternary Studies, Cambridge, United Kingdom
Other:
Bremen University, Federal Republic of Germany
Institute of Chemical and Environmental Research, Spain
Volume Title: XVI INQUA congress; Shaping the Earth; a Quaternary perspective
Source: International Union for Quaternary Research [Congress of the International Union for Quaternary Research, Vol.16, p.89-90; XVI INQUA congress; Shaping the Earth; a Quaternary perspective, Reno, NV, July 23-30, 2003. Publisher:], International
Note: In English
Summary: ODP Leg 172 Site 1060, located at 74°W, 31°N, 3500 meters water depth on the Blake Bahamas Outer Ridge (western edge of the subtropical Atlantic gyre) records the influences of the Gulf Stream and of North Atlantic Deep Water. At this site, the planktonic foraminiferal fauna demonstrate clear millennial-scale variability during MIS3. This fauna is dominated by warm species during interstadials, with 60% indicating the presence of warm surface water. In contrast, this group only makes up about 30% of the fauna during stadials. An age model has been developed by correlating abrupt shifts in the relative abundance of this faunal group with abrupt changes in the isotopic composition recorded in the Greenland ice (time scale of Johnsen et al. 2001). The percentage of carbonate, which shows high values during interstadials, obtained from the same samples, indicates the same variability. During each Greenland Stadial, Ice Rafted Debris (ird) monitored here by counting quartz grains in the 90-150 micrometer size fraction reached this subtropical location. Between stadials and interstadials SSTs as estimated by foraminiferal faunal analysis using SIMMAX varied by about 3°C. This value is supported by UK 37 SST estimates. During MIS3, both the benthic δ13C values (which are consistently lighter) and the increased fragmentation of foraminifera (indicative of carbonate dissolution) during each stadial indicate that at 3500 meters water depth the present NADW was replaced by the southerly sourced AABW at millennial time scales. Finally, by using the same proxies we compare these results to those obtained from the more coastal Site 1056 76°W, 32°N, 2200 meters water depth at present located on the Gulf Stream path. During MIS3 the summer SST for this Site are warmer and more stable those at Site 1060 (between 25 and 28°C). Percent carbonate provides a clear correlation to Site 1060 and to Greenland ice cores. There the pattern of variability in the planktonic δ18O parallels the fluctuations of the warm surface species abundances but these records do not mimic Greenland temperature. The cooling associated with Heinrich event is still evident but otherwise the surface records more closely resemble Antarctic records.
Year of Publication: 2003
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Arctic region; Atlantic Ocean; Blake-Bahama Outer Ridge; C-13; Carbon; Cenozoic; Debris; Foraminifera; GRIP; Greenland; Gulf Stream; Heinrich events; Ice rafting; Interstadial environment; Invertebrata; Isotope ratios; Isotopes; Leg 172; Marine sediments; Microfossils; North Atlantic; North Atlantic Deep Water; O-18/O-16; ODP Site 1056; ODP Site 1060; Ocean Drilling Program; Oxygen; Paleoclimatology; Paleotemperature; Planktonic taxa; Pleistocene; Protista; Quaternary; Sediments; Stable isotopes; Upper Pleistocene
Coordinates: N304535 N304535 W0742759 W0742759
N322906 N322906 W0761949 W0761949
Record ID: 2004022795
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from Desert Research Institute, Reno, NV, United States