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TitleLabrador Current fluctuation during the last glacial cycle
AuthorMao, L; Piper, D J W; Saint-Ange, F; Andrews, J T
SourceMarine Geology vol. 395, 2018 p. 234-246,
Alt SeriesEarth Sciences Sector, Contribution Series 20130248
Mediapaper; on-line; digital
ProvinceEastern offshore region
AreaAtlantic Ocean; Labrador Sea; Fram Strait
Lat/Long WENS-110.0000 20.0000 80.0000 40.0000
Subjectsmarine geology; water circulation patterns; marine sediment cores; x-ray diffraction analyses; dolomites; calcite; oxygen isotopes; radiocarbon dates; North Atlantic oceanic circulation; North Atlantic subpolay gyre; Heinrich Events; Labrador Current; Last Glacial Cycle; meltwater events
Illustrationslocation maps; lithologic logs; tables; graphs
ProgramMarine Geohazards, Public Safety Geoscience
AbstractRecords from cores 2011031-059 and 2011031-062 (hereafter 59 and 62) have been used to reconstruct changes in the vigor of the Labrador Current in northern Flemish Pass during the last glacial cycle. Grain size proxies for current speed, planktonic foramiferal delta18O, X-ray diffraction analysis for dolomite and calcite, and abundance of ice-rafted detritus (IRD) have been determined. An age model back to Marine Isotope Stage (MIS) 5 is based on recognition of seven Heinrich events from total dolomite and calcite, correlated to the IODP U1302/3 record, and confirmed by O-isotope stratigraphy and radiocarbon dates. A straight-line relationship between mean size of sortable silt (SS) and percent of sortable silt (SS%) and the lack of relationship between SS and IRD (> 500 um) indicate well-sorted sediments in cores 59 and 62, which can be used to reconstruct the paleocurrent intensity. Intensified current vigor occurred in MIS 5, 3 and 1, so that warmer periods show faster currents, probably through the Irminger Current component of the North Atlantic subpolar gyre. Low values of delta18O, SS% and SS correspond to H events, suggesting a slowdown in the Labrador Current, followed by a rapid return to strong circulation. In some cases current vigor recovery lagged slightly after the H events. Heinrich events with larger amounts of meltwater show higher current vigor. Correlation with deep-water current vigor records in the Iceland Basin show a broad correlation on a multi-millennial scale with Labrador Current variations. As our study is on a shallow sediment drift formed by the Labrador Current, one of the surface currents of the North Atlantic sub-polar gyre, it provides new evidence for a tight connection between surface current vigor fluctuation and the vigor of the deep thermohaline circulation.
Summary(Plain Language Summary, not published)
A long core from northern Flemish Pass documents changes in strength of the Labrador Current over the past 115 000 years. Current speed is a critical factor in determining geotechnical properties of sediment near the Mizzen oilfield and hence is of value in predicting sediment type at sub-bottom depths too deep to core.