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Thornalley, David JR; Barker, Stephen; Becker, Julia; Hall, Ian R; Knorr, Gregor (2013): (Table S1) Tie-points used in age model construction for ODP Leg 172 sites. PANGAEA,, Supplement to: Thornalley, DJR et al. (2013): Abrupt changes in deep Atlantic circulation during the transition to full glacial conditions. Paleoceanography, 28(2), 253-262,

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ix Ocean Drilling Program (ODP) sites, in the Northwest Atlantic have been used to investigate kinematic and chemical changes in the "Western Boundary Undercurrent" (WBUC) during the development of full glacial conditions across the Marine Isotope Stage 5a/4 boundary (~70,000 years ago). Sortable silt mean grain size(sort s) measurements are employed to examine changes in near bottom flow speeds, together with carbon isotopes measured in benthic foraminifera and % planktic foraminiferal fragmentation as proxies for changes in water-mass chemistry. A depth transect of cores, spanning 1.8-4.6 km depth, allows changes in both the strength and depth of the WBUC to be constrained across millennial scale events. Sort s measurements reveal that the flow speed structure of the WBUC during warm intervals ("interstadials") was comparable to modern (Holocene) conditions. However, significant differences are observed during cold intervals, with higher relative flow speeds inferred for the shallow component of the WBUC (~2 km depth) during all cold "stadial" intervals (including Heinrich Stadial 6), and a substantial weakening of the deep component (~3-4 km) during full glacial conditions. Our results therefore reveal that the onset of full glacial conditions was associated with a regime shift to a shallower mode of circulation (involving Glacial North Atlantic Intermediate Water) that was quantitatively distinct from preceding cold stadial events. Furthermore, our chemical proxy data show that the physical response of the WBUC during the last glacial inception was probably coupled to basin-wide changes in the water-mass composition of the deep Northwest Atlantic.
Further details:
Hoogakker, Babette A A; McCave, I Nick; Vautravers, Maryline J (2007): Antarctic link to deep flow speed variation during Marine Isotope Stage 3 in the western North Atlantic. Earth and Planetary Science Letters, 257(3-4), 463-473,
Median Latitude: 31.818153 * Median Longitude: -72.244231 * South-bound Latitude: 29.975389 * West-bound Longitude: -76.286278 * North-bound Latitude: 33.686444 * East-bound Longitude: -57.615000
Date/Time Start: 1997-02-21T00:00:00 * Date/Time End: 1997-03-25T00:00:00
Minimum DEPTH, sediment/rock: 55.60 m * Maximum DEPTH, sediment/rock: 85.30 m
172-1055 * Latitude: 32.784333 * Longitude: -76.286278 * Date/Time: 1997-02-21T00:00:00 * Elevation: -1798.1 m * Penetration: 405.4 m * Recovery: 429.4 m * Location: Carolina Slope, North Atlantic Ocean * Campaign: Leg172 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 45 cores; 405.4 m cored; 0 m drilled; 105.9% recovery
172-1057 * Latitude: 32.028861 * Longitude: -76.079222 * Date/Time: 1997-02-25T00:00:00 * Elevation: -2583.8 m * Penetration: 341.2 m * Recovery: 364.2 m * Location: Carolina Slope, North Atlantic Ocean * Campaign: Leg172 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 37 cores; 341.2 m cored; 0 m drilled; 106.7% recovery
172-1059 * Latitude: 31.674194 * Longitude: -75.418528 * Date/Time: 1997-03-03T00:00:00 * Elevation: -2985.1 m * Penetration: 286 m * Recovery: 301.9 m * Location: Blake Outer Ridge, North Atlantic Ocean * Campaign: Leg172 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 31 cores; 286 m cored; 0 m drilled; 105.6% recovery
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Event labelEvent
2Latitude of eventLatitude
3Longitude of eventLongitude
4Elevation of eventElevationm
5DEPTH, sediment/rockDepthmGeocode – mbsf
6Age modelAge modelkaThornalley, David JR
7Tie pointTie pointThornalley, David JR
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