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  • 1
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    PANGAEA
    In:  Supplement to: Hoogakker, Babette A A; Downy, Frances; Andersson, Maria A; Chapman, Mark R; Elderfield, Henry; McCave, I Nick; Lenton, Timothy M; Gruetzner, Jens (2013): Gulf Stream - subtropical gyre properties across two Dansgaard–Oeschger cycles. Quaternary Science Reviews, 81, 105-113, https://doi.org/10.1016/j.quascirev.2013.09.020
    Publication Date: 2020-01-17
    Description: Salinity increase in the subtropical gyre system may have pre-conditioned the North Atlantic Ocean for a rapid return to stronger overturning circulation and high-latitude warming following meltwater events during the Last Glacial period. Here we investigate the Gulf Stream - subtropical gyre system properties over Dansgaard-Oeschger (DO) cycles 14 to 12, including Heinrich ice-rafting event 5. During the Holocene and Last Glacial Maximum a positive gradient in surface dwelling planktonic foraminifera d18O (Globigerinoides ruber) can be observed between the Gulf Stream and subtropical gyre, due to decreasing temperature, increasing salinity, and a change from summer to year-round occurrence of G. ruber. We assess whether this gradient was a common feature during stadial-interstadial climate oscillations of Marine Isotope Stage 3, by comparing existing G. ruber d18O from ODP Site 1060 (subtropical gyre location) and new data from ODP Site 1056 (Gulf Stream location) between 54 and 46 ka. Our results suggest that this gradient was largely absent during the period studied. During the major warm DO interstadials 14 and 12 we infer a more zonal and wider Gulf Stream, influencing both ODP Sites 1056 and 1060. A Gulf Stream presence during these major interstadials is also suggested by the large vertical d18O gradient between shallow dwelling planktonic foraminifera species, especially G. ruber, and the deep dwelling species Globorotalia inflata at site 1056, which we associate with strong summer stratification and Gulf Stream presence. A major reduction in this vertical d18O gradient from 51 ka until the end of Heinrich event 5 at 48.5 ka suggests site 1056 was situated within the subtropical gyre in this mainly cold period, from which we infer a migration of the Gulf Stream to a position nearer to the continental shelf, indicative of a narrower Gulf Stream with possibly reduced transport.
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 2
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 9309 data points
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  • 3
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    PANGAEA
    In:  Supplement to: Cavaleiro, Catarina; Voelker, Antje H L; Stoll, Heather M; Baumann, Karl-Heinz; Kulhanek, Denise; Naafs, Bernhard David A; Stein, Ruediger; Gruetzner, Jens; Ventura, C; Kucera, Michal (2018): Insolation forcing of coccolithophore productivity in the North Atlantic during the Middle Pleistocene. Quaternary Science Reviews, 191, 318-336, https://doi.org/10.1016/j.quascirev.2018.05.027
    Publication Date: 2020-01-17
    Description: Coccolithophores play a key role in the oceanic carbon cycle through the biological and carbonate pumps. Understanding controls on coccolithophore productivity is thus fundamental to quantify oceanic carbon cycling. We investigate changes in coccolithophore productivity over several Pleistocene glacial-interglacial cycles using a high-resolution coccolith Sr/Ca ratio record, which is an indicator of growth rate and thus a proxy for coccolithophore productivity. We use Middle Pleistocene sediments from the North Atlantic Integrated Ocean Drilling Program (IODP) Site U1313 (41.00' N, 32.58' W) spanning Marine Isotopic Stages 16 to 10 (638 to 356 kyr). The location of the record allows us to investigate processes affecting productivity in a mid-latitude setting and to unravel the effects of temperature and regional ocean circulation. Coccolithophore productivity shows a dominant glacial-interglacial cyclicity with higher productivity during glacials, which appears to reflect the southward migration of the North Atlantic high productivity zone currently located between 45º and 55º N. Spectral analysis of the productivity record reveals a suborbital variability consistent with forcing by insolation maxima superimposed on the front migration pattern. Similar to today, coccolithophore productivity during interglacials was enhanced when insolation was at its maximum in spring or in autumn, whereas during glacials, productivity was enhanced when summer/autumn insolation was at its maximum. We show that in the studied region, coccolithophore productivity was driven by processes reflecting regional insolation. Applying this information to model experiments is required to assess if coccolithophore productivity played a significant role in past changes of atmospheric CO2.
    Type: Dataset
    Format: application/zip, 6 datasets
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  • 4
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    PANGAEA
    In:  Supplement to: Gruetzner, Jens; Jiménez-Espejo, Francisco J; Lathika, Nambiyathodi; Uenzelmann-Neben, Gabriele; Hall, Ian R; Hemming, Sidney R; LeVay, Leah J; Expedition 361 Scientists (2019): A new seismic stratigraphy in the Indian-Atlantic Ocean gateway resembles major paleo-oceanographic changes of the last 7 Ma. Geochemistry, Geophysics, Geosystems, 20(1), 339-358, https://doi.org/10.1029/2018GC007668
    Publication Date: 2020-01-17
    Description: Listed are edited, spliced, and in situ corrected data vs. various depth scales, the shipboard age scale and two-way-traveltime (TWT). The shipboard age model for Site U1475 was derived from time estimates based on a combination of major planktonic foraminifer, calcareous nanno-plankton, diatom, and paleomagnetic datums. K (wt.%) is derived from measurements of natural gamma radiation (NGR) according to De Vleeschouwer, D., Dunlea, A. G., Auer, G., Anderson, C. H., Brumsack, H., de Loach, A., et al. (2017). Quantifying K, U, and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DVJOIDESResolution. Geochemistry, Geophysics, Geosystems, 18(3), 1053-1064, doi:10.1002/2016GC006715. Description of the depth scales: The CSF-A scale (here DEPTH, sediment/rock) is specific to each hole of a site and combines the drilling depth below seafloor of the core top depth and the curated depth within a core after retrieval. The CSF-A depth scale is equivalent to the meters below seafloor (mbsf) scale known from, e.g., the Ocean Drilling Program (ODP). For the construction of the most representative single continuous sedimentary section, intervals from multiple holes need to be spliced together. This requires a common, composite depth scale (CCSF, formerly known as mcd) for a given IODP Site which is based on the correlation of coeval, laterally continuous features seen in the physical properties in all drilled holes (which will generally occur at different depths on the CSF-A depth scales for each hole). Once such correlative features (tie-points) were identified at Site U1475 the depth of individual cores was offset relative to CSF-A in that hole, resulting in the Composite Curated depth below Sea Floor (CCSF-A) depth scale (here Depth composite) for each hole. By combining selected intervals from Holes U1475B, C, E and F between the previously established tie points a complete stratigraphic section (splice) was constructed. The designated depth scale of the splice is the CCSF-D scale. CCSF-D applies only to intervals included in the splice and intervals not included in the primary splice retain the CCSF-A scale. The CCSF-A scale does not result in alignment of all coeval features because of the differing effects of coring-induced stretching and squeezing among cores, as well as sedimentological differences between holes. For our study it was desirable to map into the splice those intervals not included in the splice itself. We accomplished this by simultaneously comparing color reflectance (b*) and NGR for all holes with subsequent identification of correlative tie points at the highest possible resolution and linear adjustments of depths between ties. This adjusted depth is designated as the CCSF-C depth scale (here Depth composite revised), and to the extent that the correlations are accurate, the CCSF-C and CCSF-D scales are equivalent. CCSF-C and -D typically exceed the in situ depth (core depth below sea floor CSF-A) by ~10%. The growth rate of the CCSF-D depth scale, relative to CSF-A is on average 9.5% for all holes. Thus to correct for the depth offset a linear compression - Depth (m CCSF-B) = Depth (m CCSF-C)/1.095 - was applied to the entire depth so that the compressed core length was equal to the interval cored. The CCSF-B scale (here Depth composite corrected) hence indicates the in situ depth in meters below the seafloor (mbsf).
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 5
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 89 data points
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  • 6
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 16 data points
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  • 7
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    PANGAEA
    In:  Supplement to: Gruetzner, Jens; Higgins, Sean M (2010): Threshold behavior of millennial scale variability in deep water hydrography inferred from a 1.1 Ma long record of sediment provenance at the southern Gardar Drift. Paleoceanography, 25(4), PA4204, https://doi.org/10.1029/2009PA001873
    Publication Date: 2020-01-17
    Description: Integrated Ocean Drilling Program (IODP) Site U1314 of the North Atlantic is a critical sedimentary archive record of subpolar deep water from the southern Gardar Drift for which we derived an age model of orbital resolution for the last 1.8 Ma. This chronology combined with high-resolution (cm scale) X-ray fluorescence core scanning measurements of major elements allows tracking changes in terrigenous provenance during the last 1.1 Ma. Low Potassium to Titanium (K/Ti) ratios reflect enhanced transport of basalt-derived titanomagnetites during warm climate intervals, while high K/Ti ratios indicate a dominance of acidic sediment sources typical for glacial and stadial events. Changes in K/Ti and magnetic concentration at Site 1314 are coeval with fluctuations in smectite content and grain size data from nearby piston cores, suggesting that the provenance changes are mainly controlled by variable flow of the Iceland-Scotland Overflow Water, an important branch of North Atlantic Deep Water. Furthermore, K/Ti variations on orbital time scales show a striking similarity to the deep sea d13C record from ODP Site 607. Pervasive features of the K/Ti time series during and after the Mid-Pleistocene Transition are suborbital changes similar to Dansgaard/Oeschger and Bond oscillations that appear to be strongly amplified during ice growth phases when global benthic d18O was within the range of ~4.1-4.6 per mil. The strong increase in variability of sediment provenance and subsequently deep hydrography at benthic d18O values below ~4.1 suggests that the extent of glaciations and, therefore, sea level corresponding to this value constitutes an important physical threshold that was persistent at least for the last 1.1 Ma.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 8
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 33 data points
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  • 9
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 7 data points
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  • 10
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 232 data points
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