Sortable silt cycles in Svalbard slope sediments 74–0 ka

Abstract

The grain size of sortable silt (SS, 10-63 mm) was studied in sediment core JM04-025PC from a sediment drift on the lower part of the western Svalbard slope. The study aims to reconstruct the bottom current activity and intermediate water circulation in the Greenland Sea. The SS record covers the last 74 ka and shows consistent millennial-scale oscillations in grain size. The youngest part of the record (<25 ka) is well correlated with the few available previously published reconstructions of grain size from the North Atlantic Ocean and the Nordic seas. Fining of SS occurs during four well-known regional cold climatic intervals, the 8.2-ka cold spell, the Younger Dryas and North Atlantic Heinrich Events H1 and H2, as well as during a local meltwater event at 14.4-14.7 ka, possibly coinciding with the Older Dryas. Also before 25 ka, grain size oscillated in pace with the Northern Hemisphere climate with finer grain sizes during cold periods and coarser grain sizes during warm periods. The fining of SS indicates reduced bottom current strength and reduced water exchange between the Greenland Sea and the Arctic Ocean during regional climate cooling events, and probably also reduced deep ocean convection in the Greenland Sea gyre.

Ice‐rafting patterns on the western Svalbard slope 74–0 ka: interplay between ice‐sheet activity, climate and ocean circulation

“…; Jessen et al . ), (B) JM 04‐025 PC (Jessen & Rasmussen ) and (C) JM 03‐374 PC (Jessen & Rasmussen ) correlated with JM 05‐031 GC from Rasmussen et al . () (D, E).…”

“…Laminated sediments were also deposited during the MIS 4/3 transition (Vogt et al . ; Rasmussen & Thomsen ; Jessen & Rasmussen ), but were not as prominent as the layers dated to c . 14.5 ka.…”

“…Correlation between (A) δ 18 O record of Greenland NGRIP ice‐core (data from NGRIP Members ) and (B) grain size of sortable silt in core JM 04‐025 PC with horizontal green bars marking location of laminated clay layers (data from Jessen & Rasmussen ). Marine Isotope Stages ( MIS ) are indicated (right column).…”

“…). The whole core has been studied for stable isotope values and grain‐size of sortable silt (Jessen & Rasmussen ). For core JM03‐374PC, AMS 14 C dates have been published by Jessen et al .…”

“…Three high-resolution piston cores were taken from the western Svalbard slope during cruises with RV 'Jan Mayen' (now RV 'Helmer Hanssen') in 2003 and 2004: JM03-373PC Jessen et al 2010), JM03-374PC (Jessen 2005) and JM04-025PC (Jessen et al 2010;Jessen & Rasmussen 2015) (Fig. 1).…”