Description: We report the intercalibration of paleomagnetic secular variation (PSV) and radiocarbon dates of two expanded postglacial sediment cores from geographically proximal, but oceanographically and sedimentologically contrasting settings. The objective is to improve relative correlation and chronology over what can be achieved with either method alone. Core MD99-2269 was taken from the Húnaflóaáll Trough on the north Iceland shelf. Core MD99-2322 was collected from the Kangerlussuaq Trough on the east Greenland margin. Both cores are well dated, with 27 and 20 accelerator mass spectrometry 14C dates for cores 2269 and 2322, respectively. Paleomagnetic measurements made on u channel samples document a strong, stable, single-component magnetization. The temporal similarities of paleomagnetic inclination and declination records are shown using each core's independent calibrated radiocarbon age model. Comparison of the PSV records reveals that the relative correlation between the two cores could be further improved. Starting in the depth domain, tie points initially based on calibrated 14C dates are either adjusted or added to maximize PSV correlations. Radiocarbon dates from both cores are then combined on a common depth scale resulting from the PSV correlation. Support for the correlation comes from the consistent interweaving of dates, correct alignment of the Saksunarvatn tephra, and the improved correlation of paleoceanographic proxy data (percent carbonate). These results demonstrate that PSV correlation used in conjunction with 14C dates can improve relative correlation and also regional chronologies by allowing dates from various stratigraphic sequences to be combined into a single, higher dating density, age-to-depth model.

Description: Changes in the Holocene interaction of the (i) cold/fresh East Greenland Current (EGC) and (ii) warm/saline Irminger Current (IC) in northern Denmark Strait have been reconstructed from benthic and planktic foraminifera assemblages, ice-rafted debris, grain-size analyses and quantitative X-ray diffraction. During the time from c. 10 600 to 8000 cal a BP, palaeoceanographic reconstructions reveal waning deglacial influence from the receding Greenland Ice Sheet and presence of a strong EGC caused low surface water productivity. From c. 8000 cal a BP, a predominant influence of Atlantic-sourced IC waters on subsurface water conditions became established in northern Denmark Strait, which accompanied low surface water productivity. Relatively warm surface and subsurface water conditions, i.e. reduced EGC and strong IC influence, are found from c. 6500 to 4500 cal a BP, representing Holocene optimum-like conditions. A mid- to late Holocene EGC strengthening caused increased stratification and formation of a distinct halocline. However, we recognize millennial-scale periods of reduced stratification by an enhanced influence of Atlantic-sourced IC Water on surface water conditions: (i) at c. 2500–1400 cal a BP - the time of the Roman Warm Period and (ii) at c. 300 cal a BP - the later part of the Little Ice Age. These periods of oceanic warming probably relate to changes in the Subpolar Gyre dynamics that led to enhanced entrainment of Atlantic-sourced IC Water into northern Denmark Strait.

Description: Quantitative X-ray diffraction (qXRD) mineralogy of bedrock, ice-rafted, and fluvial clasts, 239 seafloor samples (〈2 mm), and samples from two long piston cores were used to (i) define regional patterns and sources within Baffin Bay, (ii) evaluate two areas from west Greenland and east Baffin Island in more detail, and (iii) apply these findings to the interpretation of downcore variations in sediment sources. A sediment-unmixing program is used to define surface regional mineral assemblages and to examine changes in sediment sources in cores HU2013029-77PC (southern Baffin Island slope) and HU2008029-8PC (Davis Strait) during Marine Isotope Stages 1 through 3. Distinct regional patterns are observed in the association between the mineralogy of surface sediments and carbonate and basalt bedrock outcrops. Detailed analysis of seafloor samples from the west Greenland troughs and Baffin Island fjords show regional differences in mineralogy, with sediments derived from the Foxe Fold Belt (north-central Baffin Island) being mineralogically distinct from sediments to the north and south. Grain-size spectra from the west Greenland troughs suggested an association between grain-size spectra and mineral assemblages. Sediment unmixing of qXRD data from the two piston cores shows discrete intervals where one or more mineral sources were dominant. However, chronological control is such that it is unclear whether the various ice streams draining into Baffin Bay behaved synchronously.