Origin of unusually thick Heinrich layers in ice-proximal regions of the northwest Labrador Sea

Rashid, Harunur; Hesse, Reinhard; Piper, David J. W.

doi:10.1016/s0012-821x(03)00030-x

Cited by 47 publications

(75 citation statements)

References 38 publications

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“…To decipher the internal sedimentary structures, X-radiographs were made from 1-cm thick sediment slabs (Rashid et al, 2003a). Cores were subsampled at 2.5e5 cm intervals with 10e25 cm 3 plastic vials, and dried in an oven at 63 C for 24 h. Bulk carbon content, carbonate, and total organic carbon were analyzed from 0.5 g of dry sediment using a LECO CS-125 infrared analyzer.…”

Section: Methodsmentioning

confidence: 99%

“…The >150 mm fraction was used to pick foraminifera, and the weights of foraminifera and lithic grains from this fraction were recorded. IRD is defined as sediment coarser than 150 mm (Rashid et al, 2003a;Rashid and Piper, 2007 Rashid et al, 2003aRashid et al, , 2011; for detailed description). For several cores, and especially core MD99-33, lack of adequate N. pachyderma (s) prevented us from constructing a complete oxygen isotope stratigraphy.…”

Section: Methodsmentioning

confidence: 99%

“…Nepheloid-flow deposit corresponds to a massive laminated facies characterized by a succession of thin IRD, mud and silt layers. These units usually show light brown to brown color possibly related to high carbonate content (Khodabakhsh, 1997;Rashid et al, 2003a). Nevertheless, the overall color can appear darker due to the variation in thickness of silt and IRD layers.…”

Section: Core Lithofaciesmentioning

confidence: 99%

“…(Table 2). 32 dates are published Thomas et al, 2003;Rashid et al, 2003aRashid et al, ,b, 2011Rashid and Piper, 2007; Huppertz and Piper, C-AMS dates were determined on N. pachyderma (s) (Nps) which were converted to calendar age (BP) by using Calib 6.0.1 (Reimer et al, 2009) online calibration program (see text). and H2.…”

Section: Core Lithofaciesmentioning

confidence: 99%

“…18 O in N. pachyderma (s) Hillaire-Marcel et al, 1994;Hesse and Khodabakhsh, 1998;Rashid et al, 2003a). The D/O iceberg-rafting events in the North Atlantic have been a topic of research for the last decade (Bond et al, 1999;Peck et al, 2008;Scourse et al, 2009;Haapaniemi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Fine scale sediment structure and geochemical signature between eastern and western North Atlantic during Heinrich events 1 and 2

Rashid

Saint‐Ange

Barber

et al. 2012

Quaternary Science Reviews

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a b s t r a c tHeinrich iceberg-rafting events 1 and 2 (H1 and H2) in the Labrador Sea are identified by their typical nepheloid-flow deposit sedimentary structure, high bulk carbonate, increase in iceberg-rafted detritus (IRD), and depletion of d18 O in the surface-dwelling foraminifer, Neogloboquadrina pachyderma (s). Hlayers in this region have sedimentological characteristics different than those in the North Atlantic, and are consist of IRD interspersed in pelagic sediments. High resolution 14 C-AMS dates allowed us to delineate the leads and lags in instability between different ice-streams of the former Laurentide icesheet (LIS). Our data suggest that the discharge from the Hudson Strait ice-stream was followed by Cumberland Sound ice-sheet during H1 and H2. New radiogenic isotopes from the ice-proximal and surficial sediments of the greater Hudson Strait region and Labrador Sea H0, H1 and H2 layers suggest that carbonate-rich layers were only derived from Hudson Strait, not Baffin Bay. Fine scale structure of H1 and H2 intervals in Labrador Sea slope cores is characterized by two lithic peaks dominated by detrital carbonate grains and a single peak in cores from the central Labrador Sea. A similar pattern in the structure of H1 and H2 is observed along the western European margin. These findings contrast with North Atlantic H1 and H2 intervals, which are characterized by a peak of carbonate-rich grains, followed by a peak of quartz and volcanic grains. This comparison with North Atlantic and western European margin cores leads us to suggest that the coupling or lack thereof, between the LIS and European ice-sheet, is related to the depositional processes occurring along the margins, as well as the distance from the sources and the ability of the oceanic currents to disperse icebergs. Any significant change in ice-sheet dynamics would be recorded close to the ice-sheet margin, while distal locations would only record extreme events. We hypothesize that the discordance between the findings reported in the literature is most likely similar to the difference between the upper slope/ deep Labrador sites and the Flemish Pass site described in this contribution but requires vigorous testing.Crown

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Core Lithofaciesmentioning

confidence: 99%

Section: Core Lithofaciesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fine scale sediment structure and geochemical signature between eastern and western North Atlantic during Heinrich events 1 and 2

Rashid

Saint‐Ange

Barber

et al. 2012

Quaternary Science Reviews

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Threshold behavior of a marine‐based sector of the East Antarctic Ice Sheet in response to early Pliocene ocean warming

et al. 2015

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We investigate the stability of the East Antarctic Ice Sheet (EAIS) on the Wilkes Land continental margin, Antarctica, utilizing a high-resolution record of ice-rafted debris (IRD) mass accumulation rates (MAR) from Integrated Ocean Drilling Program Site U1359. The relationship between orbital variations in the IRD record and climate drivers was evaluated to capture changes in the dynamics of a marine-based ice sheet in response to early Pliocene warming. Three IRD MAR excursions were observed and confirmed via scanning electron microscope microtextural analysis of sand grains. Time series analysis of the IRD MAR reveals obliquity-paced expansions of the ice sheet to the outer shelf prior to~4.6 Ma. A decline in the obliquity and a transition into a dominant precession response of IRD MAR occur at~4.6 Ma along with a decline in the amplitude of IRD MAR maxima to low background levels between~4.0 and~3.5 Ma. We speculate that as sea surface temperatures began to peak above 3°C during the early Pliocene climatic optimum, the ice shelves thinned, leading to a greater susceptibility to precession-forced summer insolation and the onset of persistent retreat of a marine-based portion of the EAIS.

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Anatomy of Heinrich Layer 1 and its role in the last deglaciation

et al. 2017

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X‐ray fluorescence (XRF) core scanning and X‐ray computed tomography data were measured every 1 mm to study the structure of Heinrich Event 1 during the last deglaciation at International Ocean Discovery Program Site U1308. Heinrich Layer 1 comprises two distinct layers of ice‐rafted detritus (IRD), which are rich in detrital carbonate (DC) and poor in foraminifera. Each DC layer consists of poorly sorted, coarse‐grained clasts of IRD embedded in a dense, fine‐grained matrix of glacial rock flour that is partially cemented. The radiocarbon ages of foraminifera at the base of the two layers indicate a difference of 1400 14C years, suggesting that they are two distinct events, but the calendar ages depend upon assumptions made for surface reservoir ages. The double peak indicates at least two distinct stages of discharge of the ice streams that drained the Laurentide Ice Sheet through Hudson Strait during HE1 or, alternatively, the discharge of two independent ice streams containing detrital carbonate. Heinrich Event 1.1 was the larger of the two events and began at ~16.2 ka (15.5–17.1 ka) when the polar North Atlantic was already cold and Atlantic Meridional Overturning Circulation (AMOC) weakened. The younger peak (H1.2) at ~15.1 ka (14.3 to 15.9 ka) was a weaker event than H1.1 that was accompanied by minor cooling. Our results support a complex history for Heinrich Stadial 1 (HS1) with reduction in AMOC during the early part (~20–16.2 ka) possibly driven by melting of European ice sheets, whereas the Laurentide Ice Sheet assumed a greater role during the latter half (~16.2–14.7 ka).

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Origin of unusually thick Heinrich layers in ice-proximal regions of the northwest Labrador Sea

Cited by 47 publications

References 38 publications

Fine scale sediment structure and geochemical signature between eastern and western North Atlantic during Heinrich events 1 and 2

Fine scale sediment structure and geochemical signature between eastern and western North Atlantic during Heinrich events 1 and 2

Threshold behavior of a marine‐based sector of the East Antarctic Ice Sheet in response to early Pliocene ocean warming

Anatomy of Heinrich Layer 1 and its role in the last deglaciation

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