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  • 1
    Electronic Resource
    Electronic Resource
    A 36 Ky record of iceberg rafting and sedimentation from north-west Iceland (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 21 (2002), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Evidence from north-west Iceland's shelf and fjords is used to develop a scenario for environmental change during the last 36 cal Ky. The retreat history of the Iceland Ice Cap during the last deglaciation is delineated through lithofacies studies, carbon analyses and magnetic susceptibility, and studies of ice-rafted debris (IRD) in sediment cores. Sedimentological data from lake Efstadalsvatn, Vestfirdir peninsula, trace the glacier retreat on land. In two of the high resolution shelf cores we detect near continuous IRD accumulation from 36 to 11 cal Kya. However, IRD is absent in the cores from ca. 22 to 19 cal Kya, possibly indicating more extensive landfast sea ice conditions. All cores show intensified IRD during the Younger Dryas chronozone; the fjord cores show a continuous IRD record until 10 cal Kya. Magnetic susceptibility and carbon analyses from Efstadalsvatn reveal the disappearance of local ice in the basin just before 10.5 cal Kya. No IRD was detected in the sediment cores during 10 to Ø4 cal Kya. Some indication of cooling occurs between 4 and 3 cal Kya, with a fresh input of IRD in fjord cores after 1 cal Kya.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.2002.tb00083.x
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  • 2
    Electronic Resource
    Electronic Resource
    Establishing chronologies from acid-insoluble organic 14C dates on antarctic (Ross Sea) and arctic (North Atlantic) marine sediments (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 17 (1998), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: To compare north and south polar marine paleoenvironments over the last 30,000 years, comparable chronological (radiocarbon) records must be developed and refined. Many areas in the polar regions do not preserve marine carbonates (foraminifera, mollusks), and thus age determinations, of necessity, are based on the acid-insoluble organic (AIO) fraction of the sediment. Although AIO ages are problematic and rarely used in the Arctic, they provide reasonable and consistent chronologies for the Ross Sea, Antarctica. AIO dates are meaningful in the Ross Sea because there are relatively high levels of productivity, good preservation of marine biogenic material in the sediment, and little input of terrigenous sediment and old/dead carbon. Event stratigraphy based upon proxy records of biogenic silica and δ13C can be used to assess the reliability of the AIO dates and surface age corrections. Reconstructed time-series of changes in the biogenic silica content of cores from the western Ross Sea show apparent similarities with the ‘classic’deglacial climate sequence of the northern North Atlantic. Once the absolute ages of the antarctic AIO dates are constrained by independently dated records to validate surface age corrections, it will be possible to directly compare the timing of events such as ice-rafting events in the sedimentary record.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.1998.tb00272.x
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  • 3
    Electronic Resource
    Electronic Resource
    Quartz sand grain shape and other criteria used to distinguish glacial and non-glacial events in a marine core from Frobisher Bay, Baffin Island, N.W.T., Canada (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 32 (1985), S. 0 
    Details
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Analyses of quartz sand grain shape, sediment influx rates and foraminifera define glacial and non-glacial episodes in a 9.69 m core from Frobisher Bay, Arctic Canada. Five radiocarbon dates on organic matter provide a preliminary core chronology, with a basal date of 11,910 yr BP. Quartz sand grain morphology is measured for samples at seven core levels using: (1) Fourier shape analysis; (2) percentage of grain surface conchoidally fractured. Samples at 2.0 and 7.5 m are most fractured and have Fourier roughness coefficients similar to particles sampled directly from glacier ice. These two samples probably represent glacial events in the core. Major intervals of non-carbonate sand influx occur at 9.0–4.5 m and 3.5–1.5 m, separated by several thousand years of slower sedimentation. Detrital carbonate influx rates are relatively high prior to 4.3 m, then decline rapidly indicating a shift in sediment provenance from limestones flooring Frobisher Bay to rafting from far-travelled icebergs. Bio- and lithostratigraphic analysis allows definition of five core units: (1) an environment similar to today below 8.5 m; (2) glacial conditions from 8.5–6.8 m, associated with ice proximal to the core site; (3) ameliorating conditions from 6.8 to 3.2 m; (4) cooler conditions from 3.2 to 0.5 m, probably related to increased iceberg flux rather than neoglacial advances of nearby ice caps; (5) an environment similar to today from 0.5 m. Sand grains sampled at 7.5 and 2.0 m, whose shapes indicate they are derived from glacier ice, lie within the cooler or glacial units defined from foraminiferal analysis. This indicates that quantitative measurement of particle surface morphology can provide useful environmental information in studies of marine cores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3091.1985.tb00496.x
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  • 4
    Electronic Resource
    Electronic Resource
    Late Quaternary ice extent and glacial history from the Djúpáll trough, off Vestfirdir peninsula, north-west Iceland: a stacked 36 cal. Ky environmental record (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 21 (2002), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Djúpáll is a Ø90 km long by 15 km wide trough which extends from Ísafjardardjúp to the shelf break above Blosseville Basin, north of the Denmark Strait. We present 3.5 kHz seismic profiles from this trough and data from cores collected in 1996 (JM96-1232 and −1234) and five cores collected on cruise B997. We pay particular attention to B997-338 as this core recovered sediments ranging in age between 12 and 36 cal. Ky BP. This is the first such record from the Iceland continental shelf. Dating control is provided by AMS 14C dates and the occurrence of the Saksunarvatn tephra. X-radiographs of the cores enable us to quantify the input of iceberg-rafted detritus (IRD) and to describe the lithofacies. The sediment matrix is fine-grained and might represent either rain-out of suspended sediment plumes or distal turbidites. IRD is present from ca. 12 cal. Ky BP throughout the next 24 cal. Ky with some IRD-free intervals. Using sediment magnetic properties, sampled at 1 cm (ø100 yrs/sample) resolution, we provide a stacked environmental record which includes marine isotope stages 1, 2 and part of 3. The sediment magnetic properties kARM and IRM(60), and carbonate and TOC, show multi-millennia quasi-periodic cycles, but there are no obvious events coeval with the North Atlantic Heinrich events. Our data indicate that at the Last Glacial Maximum on the Vestfirdir peninsula (VP), north-west Iceland, ice did not reach the shelf break, but was probably grounded near the mouth of Ísafjardardjúp. A rapid increase in the rate of sediment accumulation suggests that deglaciation of the VP occurred mainly between 11 and 15 cal. Ky BP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.2002.tb00074.x
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  • 5
    Electronic Resource
    Electronic Resource
    Geomagnetic secular variations (inclination) of high latitude fiord cores: eastern Canadian Arctic (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 8 (1990), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Paleomagnetic measurements are reported from 11 piston cores, from the fiords and shelf of eastern Baffin Island, N.W.T., between latitudes 66 and 72 degrees north. The majority of the measurements arc from bioturbated, massive, or laminated mud, with some drop-stones and graded sand beds. Corrected radiocarbon dates on the acid-insoluble organic matter fraction, supplemented by AMS dates on in situbivalves, indicate that all cores extend into the early Holocene, and three extend into the latest Pleistocene Sedimentation rates averaged between 0.2m/ka and 1.4m/ka. Because of varying sedimentation rates, the depth scales are converted to 100 or 200 yr/sample time series. The results indicate a scries of geomagnetic secular oscillations with amplitudes in inclination of c. 10 degrees. A stacked record from four piston cores suggests seven major oscillations in inclination. Times when inclinations consistently exceeded 80° occurred c. 1,400, 4,500, and 8,000 B.P. The most characteristic oscillation occurred c.1,400 ± B.P., when inclinations were nearly vertical. Inclination errors are associated with gravity flows and/or with an increase in sand content, or changes in physical properties. In one core an interval of reverse polarity is attributed to a slump.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.1990.tb00387.x
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  • 6
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    The role of the Iceland Ice Sheet in the North Atlantic during the late Quaternary: a review and evidence from Denmark Strait (2008)
    Wiley-Blackwell
    In:  Journal of Quaternary Science, 23 (1). pp. 3-20.
    Details
    Publication Date: 2017-04-06
    Description: Investigations indicate that the Iceland Ice Sheet was reduced in size during MIS 3 but readvanced to the shelf break at the LGM. Retreat occurred very rapidly around 15 k–16 k cal. yr BP. By contrast, the margin of the ice sheet on the East Greenland shelf, north of the Denmark Strait, was at or close to the shelf break during MIS 3 and 2 and retreat starting ∼17 k cal. yr BP. Quantitative X-ray diffraction analysis of the 〈2 mm sediment fraction was undertaken on 161 samples from Iceland and East Greenland diamictons, and from cores on the slopes and margins of the Denmark Strait. Weight% mineralogical data are used in a principal component analysis to differentiate sediments derived from the two margins. The first two PC axes explain 52% of the variance. These associations are used to characterise sediments as being affiliated with (a) Iceland, (b) East Greenland or (c) mixed. The contribution from Iceland becomes prominent during MIS 2. The extensive outcrop of early Tertiary basalts on East Greenland between 68° and 71° N is an alternative source for basaltic clasts and North Atlantic sediments with εNd(0) values close to ±0.
    Type: Article , PeerReviewed
    Format: text
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  • 7
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    Seeking a Holocene drift ice proxy: non-clay mineral variations from the SW to N-central Iceland shelf: trends, regime shifts, and periodicities (2009)
    Wiley-Blackwell
    In:  Journal of Quaternary Science, 24 (7). pp. 664-676.
    Details
    Publication Date: 2016-06-29
    Description: Quantitative X-ray diffraction analysis of the 〈2mm sediment fraction was carried out on 1257 samples (from the seafloor and 16 cores) from the Iceland shelf west of 188 W. All but one core (B997-347PC) were from transects along troughs on theNW to N-central shelf, an area that in modern and historic times has been affected by drift ice. The paper focuses on the non-clay mineralogy of the sediments (excluding calcite and volcanic glass). Quartz and potassium feldspars occupy similar positions in an R-mode principal component analysis, and oligoclase feldspar tracks quartz; these minerals are used as a proxy for ice-rafted detritus (IRD). Accordingly, the sum of these largely foreign minerals (Q&K) (to Icelandic bedrock) is used as a proxy for drift ice. A stacked, equi-spaced 100 a record is developed which shows both low-frequency trends and higher-frequency events. The detrended stacked record compares well with the flux of quartz (mg cm-2 a-1) at MD99-2269 off N Iceland. The multi-taper method indicated that there are three significant frequencies at the 95% confidence level with periods of ca. 2500, 445 and 304 a. Regime shift analysis pinpoints intervals when there was a statistically significant shift in the average Q&K weight %, and identifies four IRDrich events separated by intervals with lower inputs. There is some association between peaks of IRD input, less dense surface waters (from d18O data on planktonic foraminifera) and intervals of moraine building.
    Type: Article , PeerReviewed
    Format: text
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