Evidence for an additional Heinrich event between H5 and H6 in the Labrador Sea

Abstract

[1] An additional Heinrich ice-rafting event is identified between Heinrich events 5 and 6 in eight cores from the Labrador Sea and the northwest Atlantic Ocean. It is characterized by sediment rich in detrital carbonate (40% CaCO 3 ) with high concentration of floating dropstones, high coarse-fraction (% > 150 mm) content, and has a sharp contact with the underlying but grades into the overlying hemipelagic sediment. It also shows lighter d18 O Npl values, indicating freshening due to iceberg rafting and/or meltwater discharge. This event is correlated with Dansgaard-Oeschger event 14 and interpreted as an additional Heinrich event, H5a. The thickness of H5a in the Labrador Sea reaches up to 220 cm. This additional Heinrich event has also been reported in cores PS2644 and SO82-5 from the northern North Atlantic. With the recognition of H5a the temporal spacing between Heinrich events 1 to 6 becomes more uniform ($7 ka).

Hindcasting the continuum of Dansgaard–Oeschger variability: mechanisms, patterns and timing

“…Whereas the IRD pulse is well pronounced in the composite IRD time series (Fig. 1), as well as in records from the Irminger basin (SU 90-24) (Elliot et al, 2002), the southern Gardar Drift (JPC-13) (Hodell et al, 2010) and from the Iberian margin (MD95-2040) (Schönfeld et al, 2003); it appears to be absent in other southwestern Atlantic IRD records (e.g., Grousset et al, 1993;Rashid et al, 2003;Nave et al, 2007). We move on to a more detailed comparison with other temperature reconstructions from the North Atlantic and Mediterranean realm.…”

“…6 and data with stadial (interstadial) conditions corresponding to increased aridity (pluvials). While the pollen-derived precipitation estimate (Sánchez-Goñi et al, 2002) and the model output suggest much drier conditions over the Iberian region during HS5, the chronology of the proxy record is based on a graphic correlation with the GISP2 ice core, which places the HS5 much later than the new GICC05 chronology (Obrochta et al, 2014). It should be noted that reflectance and magnetic susceptibility are indirect hydroclimate proxies and thus cannot give quantitative estimates.…”

“…Comparing the simulated northern hemispheric rainfall changes on a regional scale with hydroclimate reconstructions for the Mediterranean region (Sánchez-Goñi et al, 2002), the Cariaco Basin (Deplazes et al, 2013), the Arabian Sea (Deplazes et al, 2013), eastern China (Wang et al, 2001) (Fig. 5) and Central America (Hodell et al, 2008) (Fig.…”

Antarctic link to deep flow speed variation during Marine Isotope Stage 3 in the western North Atlantic

“…Heinrich events H3, H4 and H5 do not coincide with slow flow but are all preceded by flow speed minima (SE0, SE1, and SE2 respectively). Lastly, Heinrich event H5a/Stadial 15 [41] appears associated with a decrease in flow vigour (SE3), lasting well into the following warm interstadial 14 (Fig. 3).…”

“…A 1-2-1 weighted three point smoothing (thin grey line) and 1-2-3-2-1 (thick black line) smoothing were applied to the P SS data. Several D/O interstadials and Heinrich events (H, grey bars) are indicated, and H5a (S15) was added by Rashid et al [41]. Also indicated are ′slow events′ of reduced flow vigour SE0 to SE4 (thick lined circles).…”