Northwest Atlantic Sediment Data Across the Marine Isotope Stage 5a/4 Boundary Thornalley, D.J.R.; Barker, S.; Becker, J.; Hall, I.R.; Knorr, G. Thornalley, D.J.R. Barker, S. Becker, J. Hall, I.R. Knorr, G. Dansgaard-Oeschger cycles Heinrich Events earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,composited,null,N,null) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,smoothed,null,N,3-point smooth) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 19 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,early MIS4 normalized to long-term mean) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,D-O stadial 20 (CO 20) normalized to long-term mean) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides sp.,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 20 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,D-O stadial 19 (CO 19) normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,Heinrich stadial 6 normalized to long-term mean) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,resampled,null,N,500yr bins) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides sp.,null,per mil VPDB,null,paleoceanography,smoothed,null,N,3-point smooth) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,D-O stadial 19 (CO 19) normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,Last Glacial Maximum normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,Last Glacial Maximum normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,normalized to site long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 21 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 21 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 19 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,early MIS4 normalized to long-term mean) earth science/paleoclimate/paleoceanography (delta 18O,Globigerinoides ruber,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Globigerinoides ruber,null,per mil VPDB,null,paleoceanography,smoothed,null,N,3-point smooth) earth science/paleoclimate/paleoceanography (delta 18O,benthic foraminifer,null,per mil VPDB,null,paleoceanography,null,null,N,Cibicidoides lobatulus and Cibicidoides wuellerstorfi) earth science/paleoclimate/paleoceanography (delta 18O,benthic foraminifer,null,per mil VPDB,null,paleoceanography,smoothed,null,N,Cibicidoides lobatulus and Cibicidoides wuellerstorfi; 3-point smooth) earth science/paleoclimate/paleoceanography (foraminifer fragmentation,null,null,percent,null,paleoceanography,null,null,N,planktic fragmentation) earth science/paleoclimate/paleoceanography (foraminifer fragmentation,null,null,percent,null,paleoceanography,smoothed,null,N,3-point smooth) earth science/paleoclimate/paleoceanography (sand,sediment,null,percent,null,paleoceanography,null,null,N,>63µm) earth science/paleoclimate/paleoceanography (delta 18O,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,Heinrich stadial 6 normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Cibicidoides sp.,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,D-O stadial 20 (CO 20) normalized to long-term mean) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,null,micrometer,null,paleoceanography,normalized,null,N,D-O interstadial 20 normalized to long-term mean; silt fraction) earth science/paleoclimate/paleoceanography (sortable silt mean grain size,null,one standard error,micrometer,null,paleoceanography,normalized,null,N,Holocene normalized to long-term mean) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (ODP1060>LATITUDE 30.766667>LONGITUDE -74.466667) (ODP 1055>LATITUDE 32.783333>LONGITUDE -76.283333) (ODP 1057>LATITUDE 32.033333>LONGITUDE -76.05) (Western North Atlantic Ocean>LATITUDE >LONGITUDE ) (ODP 1059>LATITUDE 31.683333>LONGITUDE -75.416667) (ODP1061>LATITUDE 29.933333>LONGITUDE -73.6) (ODP1063>LATITUDE 33.683333>LONGITUDE -57.616667) Six 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 inline image 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. inline image 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. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Thornalley, D.J.R. Investigator : Barker, S. Investigator : Becker, J. Investigator : Hall, I.R. Investigator : Knorr, G. 2014-06-05 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/16556 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-normholo.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-jpc37.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1063.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-benth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-norm.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1055.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1061.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1057.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1060.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-normholo.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-jpc37.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1063.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-benth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-norm.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1055.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1061.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1057.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1060.txt English https://www.ncdc.noaa.gov/paleo/study/16556 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-normholo.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-jpc37.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1063.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059-benth.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-ss-norm.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1055.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1061.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1057.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1059.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/thornalley2013/thornalley2013-odp1060.txt Thornalley, D.J.R., S. Barker, J. Becker, I.R. Hall, and G. Knorr2013Abrupt changes in deep Atlantic circulation during the transition to full glacial conditionsPaleoceanography28253-26210.1002/palo.20025 START YEAR: 85908 cal yr BP * END YEAR: 55600 cal yr BP -76.283333 29.933333 -57.616667 33.683333