Abstract. The stable isotope composition of dissolved silicon in seawater
(δ30SiDSi) was examined at 10 stations along the GEOVIDE
section (GEOTRACES GA-01), spanning the North Atlantic Ocean
(40–60∘ N) and Labrador Sea. Variations in
δ30SiDSi below 500 m were closely tied to the distribution
of water masses. Higher δ30SiDSi values are associated with
intermediate and deep water masses of northern Atlantic or Arctic Ocean
origin, whilst lower δ30SiDSi values are associated with
DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly,
the lowest δ30SiDSi values were observed in the deep and
abyssal eastern North Atlantic, where dense southern-sourced waters dominate.
The extent to which the spreading of water masses influences the
δ30SiDSi distribution is marked clearly by Labrador Sea
Water (LSW), whose high δ30SiDSi signature is visible not
only within its region of formation within the Labrador and Irminger seas,
but also throughout the mid-depth western and eastern North Atlantic Ocean.
Both δ30SiDSi and hydrographic parameters document the
circulation of LSW into the eastern North Atlantic, where it overlies
southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi
distribution thus provides a clear view of the direct interaction between
subpolar/polar water masses of northern and southern origin, and allow
examination of the extent to which these far-field signals influence the
local δ30SiDSi distribution.
Observation of deep water microseisms in the North Atlantic Ocean using tide modulations
