Geochemical Signatures of Paleoclimate Changes in the Sediment Cores from the Gloria and Snorri Drifts (Northwest Atlantic) over the Holocene-Mid Pleistocene

Demina Demina,Lisitzin Lisitzin,Novichkova Novichkova,Kozina Kozina

doi:10.3390/geosciences9100432

Demina Demina, Lisitzin Lisitzin + Show 2 more

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https://doi.org/10.3390/geosciences9100432

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Abstract

A multiproxy study of the sediment cores taken from the Snorri Drift, formed under the influence of the Iceland–Scotland bottom contour current, and from the Gloria Drift, located southward Greenland at the boundary of Irminger and Labrador Seas, was performed. This area undergoes a variable mixing of polar waters with the warm North Atlantic current, whose intensity and direction seemed to change dramatically with the alteration of warming and cooling periods during the six marine isotope stages MIS 1-6. The relative age of this core does not exceed 190,000 cal yr BP; the average sedimentation rate was 1.94 and 2.45 cm/kyr in the Gloria and Snorri Drifts core respectively. In both the cores, the sediment records showed the downcore co-variation of ice-rafted debris (IRD); and terrigenous elements, such as Si, Al, Ti, Cr, and Zr, were revealed; their values were clearly higher in the glacial periods (MIS 2, 4, and 6) compared to interglacials (MIS 1, 3, and 5). The downcore rhythmic distributions of these elements, as well as Al/Si, Ti/Al, Fe/Al ratios exhibit an opposite trend with that of δ18O values, biogenic components (CaCO3, BioSiO2), and Si/Fe and Mn/Fe ratios.

Highlights

The North Atlantic is one of the key regions of the World Ocean characterized by the global thermohaline circulations interrelated with climate changes [1,2]
We aimed to identify changes in the geochemical characteristics of the sedimentation paleoenvironment at the Gloria and Snorri Contourite Drifts based on geochemical multielemental analysis combined with stable isotope and lithological data
We focused on the two sediment cores sampled with gravity corer: AMK-4493 recovered from the Gloria Drift (53◦ 31.22 N; 42◦ 45.74 W, 3547 m sea depth) and AI-3378 taken from the Snorri

Summary

Introduction

The North Atlantic is one of the key regions of the World Ocean characterized by the global thermohaline circulations interrelated with climate changes [1,2]. An active penetration of relatively warm and saline Atlantic waters to the Arctic Ocean during interglacial periods and deglaciation results in the heating of surface water and their transfer to higher latitudes that leads to intensification of the global ocean conveyer and melting of Arctic ice [3,4,5]. The contourite drifts were discovered about 50 years ago [7]. They are defined as sedimentary bodies formed under the influence of the system of the along-slope near-bottom currents, so contourite drifts are usually investigated to reconstruct near-bottom paleocurrents speed [8,9,10,11].

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