ALBERT

Description: Sediment depth age-models, stable carbon isotope data, and radiocarbon data are reported for a suite of sediment cores from Iberian- and Brazil Margins, in the Atlantic basin. The sediment sequences span the last deglaciation (~30,000 years to the present). Stable carbon isotopes were measured on the benthic foraminifer species Cibicidoides wuellerstorfi, in the Godwin Laboratory, University of Cambridge. Each measurement was run on 1-4 individuals with a combined mass of 50-180μg. Samples were reacted with orthophosphoric acid (100%) and analysed, in comparison with a reference gas, using a dual inlet Thermo MAT 253 mass spectrometer connected to a Kiel device. Radiocarbon dates were obtained on monospecific samples of planktonic foraminifera, Globigerinoides ruber (Brazil Margin) or Globigerina bulloides (Iberian Margin), and samples of mixed benthic foraminifera (excluding agglutinated species) picked from the 〉150μm size-fraction. Samples were graphitized in the Godwin Radiocarbon Laboratory at the University of Cambridge, using a standard hydrogen/iron catalyst reduction method. AMS-14C dates were subsequently measured at the 14Chrono Centre, Queens University Belfast. All dates are reported as 'conventional radiocarbon ages', without additional 'corrections' applied. Reservoir ages and radiocarbon ventilation ages are derived based on the sediment core chronologies, and reported as offsets between contemporary marine- and atmospheric radiocarbon ages (based on the 'Intcal13' atmospheric radiocarbon calibration curve).

Description: Component declination and inclination, determined from stepwise alternating field demagnetization data recording the Iceland Basin excursion from discrete (2x2 cm²) samples from Core MD07-3077 (see Channell et al., 2017). Age models for records of the Laschamp and Iceland Basin excursions were derived from radiocarbon dates, and from matching sea-surface temperature records to Antarctic (EPICA) air-temperature records from ice cores. The onset of the Laschamp excursion occurred during Antarctic Isotopic Maximum (AIM) 10, consistent with its occurrence during Greenland Interstadial 10. The end of the Laschamp excursion occurred prior to AIM 9 in Greenland Stadial 10. The age model is supported by synchroneity of directional and relative paleointensity manifestations of the Laschamp excursion in the marine core with peaks in EPICA10Be and nitrate flux. The Iceland Basin excursion is synchronous with the final phase of the transition from marine isotope stage (MIS) 7a to MIS 6e as recorded in the EPICA δD record. The onset of the Laschamp and Iceland Basin excursions, defined here by component inclinations 〉-40°, occurred at 41.4 ka and 190.0 ka, and durations are ~1 kyr and ~ 3.5 kyr, respectively, although these estimates depend on the criteria used to define the directional excursions. By comparison with Laschamp and Iceland Basin excursion records from the North Atlantic Ocean, the two excursions are synchronous at centennial timescales between the two hemispheres, based on synchronization of the GICC05 and AICC2012 age models for Greenland and Antarctic ice cores.

Description: Component declination and inclination, determined from stepwise alternating field demagnetization data recording the Iceland Basin excursion from u-channel samples from Core MD07-3077 (see Channell et al., 2017). Age models for records of the Laschamp and Iceland Basin excursions were derived from radiocarbon dates, and from matching sea-surface temperature records to Antarctic (EPICA) air-temperature records from ice cores. The onset of the Laschamp excursion occurred during Antarctic Isotopic Maximum (AIM) 10, consistent with its occurrence during Greenland Interstadial 10. The end of the Laschamp excursion occurred prior to AIM 9 in Greenland Stadial 10. The age model is supported by synchroneity of directional and relative paleointensity manifestations of the Laschamp excursion in the marine core with peaks in EPICA10Be and nitrate flux. The Iceland Basin excursion is synchronous with the final phase of the transition from marine isotope stage (MIS) 7a to MIS 6e as recorded in the EPICA δD record. The onset of the Laschamp and Iceland Basin excursions, defined here by component inclinations 〉-40°, occurred at 41.4 ka and 190.0 ka, and durations are ~1 kyr and ~ 3.5 kyr, respectively, although these estimates depend on the criteria used to define the directional excursions. By comparison with Laschamp and Iceland Basin excursion records from the North Atlantic Ocean, the two excursions are synchronous at centennial timescales between the two hemispheres, based on synchronization of the GICC05 and AICC2012 age models for Greenland and Antarctic ice cores.

Description: Component declination and inclination, determined from stepwise alternating field demagnetization data recording the Laschamp excursion from u-channel samples from Core MD07-3076 (see Channell et al., 2017). Age models for records of the Laschamp and Iceland Basin excursions were derived from radiocarbon dates, and from matching sea-surface temperature records to Antarctic (EPICA) air-temperature records from ice cores. The onset of the Laschamp excursion occurred during Antarctic Isotopic Maximum (AIM) 10, consistent with its occurrence during Greenland Interstadial 10. The end of the Laschamp excursion occurred prior to AIM 9 in Greenland Stadial 10. The age model is supported by synchroneity of directional and relative paleointensity manifestations of the Laschamp excursion in the marine core with peaks in EPICA10Be and nitrate flux. The Iceland Basin excursion is synchronous with the final phase of the transition from marine isotope stage (MIS) 7a to MIS 6e as recorded in the EPICA δD record. The onset of the Laschamp and Iceland Basin excursions, defined here by component inclinations 〉-40°, occurred at 41.4 ka and 190.0 ka, and durations are ~1 kyr and ~ 3.5 kyr, respectively, although these estimates depend on the criteria used to define the directional excursions. By comparison with Laschamp and Iceland Basin excursion records from the North Atlantic Ocean, the two excursions are synchronous at centennial timescales between the two hemispheres, based on synchronization of the GICC05 and AICC2012 age models for Greenland and Antarctic ice cores.

Description: Component declination and inclination, determined from stepwise alternating field demagnetization data recording the Laschamp excursion from discrete (2x2 cm²) samples from Core MD07-3076 (see Channell et al., 2017). Age models for records of the Laschamp and Iceland Basin excursions were derived from radiocarbon dates, and from matching sea-surface temperature records to Antarctic (EPICA) air-temperature records from ice cores. The onset of the Laschamp excursion occurred during Antarctic Isotopic Maximum (AIM) 10, consistent with its occurrence during Greenland Interstadial 10. The end of the Laschamp excursion occurred prior to AIM 9 in Greenland Stadial 10. The age model is supported by synchroneity of directional and relative paleointensity manifestations of the Laschamp excursion in the marine core with peaks in EPICA10Be and nitrate flux. The Iceland Basin excursion is synchronous with the final phase of the transition from marine isotope stage (MIS) 7a to MIS 6e as recorded in the EPICA δD record. The onset of the Laschamp and Iceland Basin excursions, defined here by component inclinations 〉-40°, occurred at 41.4 ka and 190.0 ka, and durations are ~1 kyr and ~ 3.5 kyr, respectively, although these estimates depend on the criteria used to define the directional excursions. By comparison with Laschamp and Iceland Basin excursion records from the North Atlantic Ocean, the two excursions are synchronous at centennial timescales between the two hemispheres, based on synchronization of the GICC05 and AICC2012 age models for Greenland and Antarctic ice cores.

Description: Two relative paleointensity (RPI) proxies (slopes of NRM/ARM and NRM/IRM) for u-channel samples from Core MD07-3076. The RPI proxies were determined from stepwise alternating field demagnetization applied to the natural remanent magnetization (NRM) and to the anhysteretic remanent magnetization (ARM) (see Channell et al., 2017). Age models for records of the Laschamp and Iceland Basin excursions were derived from radiocarbon dates, and from matching sea-surface temperature records to Antarctic (EPICA) air-temperature records from ice cores. The onset of the Laschamp excursion occurred during Antarctic Isotopic Maximum (AIM) 10, consistent with its occurrence during Greenland Interstadial 10. The end of the Laschamp excursion occurred prior to AIM 9 in Greenland Stadial 10. The age model is supported by synchroneity of directional and relative paleointensity manifestations of the Laschamp excursion in the marine core with peaks in EPICA10Be and nitrate flux. The Iceland Basin excursion is synchronous with the final phase of the transition from marine isotope stage (MIS) 7a to MIS 6e as recorded in the EPICA δD record. The onset of the Laschamp and Iceland Basin excursions, defined here by component inclinations 〉-40°, occurred at 41.4 ka and 190.0 ka, and durations are ~1 kyr and ~ 3.5 kyr, respectively, although these estimates depend on the criteria used to define the directional excursions. By comparison with Laschamp and Iceland Basin excursion records from the North Atlantic Ocean, the two excursions are synchronous at centennial timescales between the two hemispheres, based on synchronization of the GICC05 and AICC2012 age models for Greenland and Antarctic ice cores.