Description: An important tool for deep-sea temperature reconstruction is Mg/Ca paleothermometry applied to benthic foraminifera. Foraminifera of the genus Melonis appear to be promising candidates for temperature reconstructions due to their wide geographical and bathymetric distribution, and their infaunal habitat, which was suggested to reduce secondary effects from carbonate ion saturation (Δ[CO3 2−]). Here, we make substantial advances to previous calibration efforts and present new multi-lab Mg/Ca data for Melonis barleeanum and Melonis pompilioides from more than one hundred core top samples spanning in situ bottom temperatures from −1 to 16 °C, coupled with morphometric analyses of the foraminifer tests. Both species and their morphotypes seem to have a similar response of Mg/Ca to growth temperature. Compilation of new and previously published data reveals a linear dependence of temperature on Mg/Ca, with a best fit of Mg/Ca (mmol/mol) = 0.113 ± 0.005 ∗ BWT (°C) + 0.792 ± 0.036 (r2 = 0.81; n = 120; 1σ SD). Salinity, bottom water Δ[CO3 2−], and varying morphotypes have no apparent effect on the Mg/Ca-temperature relationship, but pore water Δ[CO3 2−] might have had an influence on some of the samples from the tropical Atlantic.

Description: Clay- and silt-size mineral assemblages are described from eight piston cores from the fiords and shelf on the western margin of Baffin Bay, Arctic Canada. Radiocarbon dates indicate that all the cores extend back in time to the last local glacial/interglacial transition (i.e. 8–10 ka); four extend back to between 10 and 12 ka, and HU77-021-156, located on the Southeast Baffin Island shelf, includes the entire late Foxe glacial stage. Silt- and clay-size particles constitute ca 40 and 55%, respectively, by weight of the bulk sediment. The clay-size fraction is dominated by mica; feldspars and quartz are the main constituents of the silt fraction. The fiord sediments are mainly composed of local mineralogies, but on the shelf, and at times in the fiords, exotic mineral species occur. The most important of these are detrital carbonates, derived from erosion of the Paleozoic basins in Arctic Canada and/or northwest Greenland. Both calcite and dolomite occur; calcite is the major carbonate mineral in the “southern” cores, whereas dolomite is the most abundant in cores north of 66°N. Higher inputs of carbonate species occur during regional deglaciation, 7–10 ka, and during the last 5 ka (probably reflecting increased iceberg production from northwest Greenland). Thus variations in the precentages of the carbonate minerals indicate significant shifts in Late Quaternary glacial-sediment source areas and oceanographic regimes.

Description: In the North Atlantic we define H-0 as a Heinrich-like event which occurred during the Younger Dryas chron. On the SE Baffin shelf prior to 11 ka, surface water productivity was reasonably high, as measured by the numbers of diatom and planktic foraminifera per gram, but an abrupt increase in detrital carbonate (DC-0 event) (from approximately 15% up to 50% carbonate by weight) occurred at 11 ± 14C ka and continued to circa 10 ka. These deposits, 2–6 m thick, are dominated by detrital calcite and silt- and clay-sized sediments. During this event (DC-0/H-0), ice extended onto the inner shelf but did not reach the shelf break and probably originated from a center over Labrador-Ungava. As a consequence, the pattern of ice-rafted debris and sediment provenance shown by H-O in the North Atlantic is different from that during H-1 (14.5 ka) or H-2 (20 ka) when the ice sheet extended along the axis of Hudson Strait and may have reached the shelf break; for example, there is no concrete evidence for DC-O is cores on the floor of the Labrador Sea due east of Hudson Strait (HU75-55,-56), but H-O has been noted in cores off Newfoundland and west of Ireland. A coeval carbonate event to DC-0, but this one dominated by dolomite, occurs in HU82-SU5 on the west side of Davis Strait with a source either from northern Baffin Bay or Cumberland Sound. Although other sources for North Atlantic detrital carbonate cannot be totally excluded, our evidence suggests that H-0 represents the expression of glaciological instability of the Laurentide Ice Sheet within the general region of Hudson Strait and probably to the north (Cumberland Sound and northernmost Baffin Bay). There is one younger DC event, dated circa 8.4 ka, present in sediments along the Labrador margin and in Hudson Strait, which represents the final collapse of the ice sheet within Hudson Strait and Hudson Bay.

Description: Surface sediment samples for analysis of modern foraminiferal assemblages were collected from 32 sites on the western and northern Iceland shelf during cruise B997 of the Icelandic ship Bjarni Saemundsson. The purpose of the study is to provide a basis for interpreting the variations in foraminiferal content in late glacial through Holocene sediments from cores at the same sites. Cluster analysis and principal components analysis of the benthic foraminiferal data and associated modern environmental parameters including hydrography, water depth, and sediment characteristics show that large progressive changes in the foraminiferal assemblages coincide with changes in the dominant oceanic surface currents and water masses around Iceland. The western areas of the shelf are overlain by relatively warm and saline Atlantic Water of the Irminger Current. The western shelf fauna is dominated by Cassidulina laevigata and other boreal species, whereas the planktic fauna is dominated by dextrally coiling Neogloboquadrina pachyderma. In Djúpáll, off the Northwest Peninsula, and in the shallow nearshore sites on the northern shelf, the boreal elements of the fauna diminish and arctic species become more important. However, the dominant species in these areas are Cibicides lobatulus and Astrononion gallowayi, attesting to winnowing of the shallow shelf areas by currents. In Isafjardardjúp, the large fjord indenting the Northwest Peninsula, Cassidulina reniforme and Elphidium excavatum dominate the fauna as a result of cooler waters and more variable salinity conditions. A very large faunal shift is registered in the deep basins of the northern shelf. This faunal shift coincides with large changes in salinity and temperature stratification of the water column, reflecting the presence of the East Iceland Current. The fauna in the deep basins on the northern shelf are dominated by C. neoteretis, an indicator of modified Atlantic Water, and infaunal species that reflect organic fluxes to the seabed: Nonionellina labradorica and Melonis barleeanus, and the arctic species Islandiella norcrossi and I. helenae.

Description: In the North Atlantic we define H-0 as a Heinrich-like event which occurred during the Younger Dryas chron. On the SE Baffin shelf prior to 11 ka, surface water productivity was reasonably high, as measured by the numbers of diatom and planktic foraminifera per gram, but an abrupt increase in detrital carbonate (DC-0 event) (from approximately 15% up to 50% carbonate by weight) occurred at 11 ± 14C ka and continued to circa 10 ka. These deposits, 2–6 m thick, are dominated by detrital calcite and silt- and clay-sized sediments. During this event (DC-0/H-0), ice extended onto the inner shelf but did not reach the shelf break and probably originated from a center over Labrador-Ungava. As a consequence, the pattern of ice-rafted debris and sediment provenance shown by H-O in the North Atlantic is different from that during H-1 (14.5 ka) or H-2 (20 ka) when the ice sheet extended along the axis of Hudson Strait and may have reached the shelf break; for example, there is no concrete evidence for DC-O is cores on the floor of the Labrador Sea due east of Hudson Strait (HU75-55,-56), but H-O has been noted in cores off Newfoundland and west of Ireland. A coeval carbonate event to DC-0, but this one dominated by dolomite, occurs in HU82-SU5 on the west side of Davis Strait with a source either from northern Baffin Bay or Cumberland Sound. Although other sources for North Atlantic detrital carbonate cannot be totally excluded, our evidence suggests that H-0 represents the expression of glaciological instability of the Laurentide Ice Sheet within the general region of Hudson Strait and probably to the north (Cumberland Sound and northernmost Baffin Bay). There is one younger DC event, dated circa 8.4 ka, present in sediments along the Labrador margin and in Hudson Strait, which represents the final collapse of the ice sheet within Hudson Strait and Hudson Bay.

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: Based on quantitative X-ray diffraction mineralogical analysis of cores HU2008029-0006/0008 (857-m water depth) located south of the Davis Strait sill, we seek answers to two questions: (i) the temporal correlation of NW Labrador Shelf Sea Heinrich (H-) and Baffin Bay detrital carbonate (BBDC) events, and (ii) the provenance of the sediments? A sediment-unmixing model (SedUnMix) is used to determine provenance variations. Although 12 radiocarbon dates were obtained there were many age reversals and we favour a depth/age model for HU2008029-0008PC based on correlations to well-dated neighbouring cores north and south of Davis Strait. We find no correlation between H- and BBDC events except for H-0, which appears to be a broadly synchronous event along the NE Canadian margin and is correlative with an episode of major moraine building along this flank of the Laurentide Ice Sheet. Unmixing of the sediment composition based on six potential glacial source regions indicates that the bulk of the sediment in 0008PC is derived from glacial erosion of West Greenland, but is punctuated by intervals when dolomite-rich sediments, derived from outcrops north of Baffin Bay, dominate the composition. Estimated dates on these BBDC events are -13, 25 and 30–38 cal ka BP.