Heinrich event-0 (DC-0) in sediment cores from the northwest Labrador Sea: recording events in Cumberland Sound?

1998 ◽  
Vol 35 (5) ◽  
pp. 510-519 ◽  
Author(s):  
Matthew E Kirby
Keyword(s):  
Sediment Cores ◽  
Ice Sheet ◽  
Transport Processes ◽  
Labrador Sea ◽  
Sediment Layer ◽  
Strong Constraint ◽  
The North ◽  
Cumberland Sound ◽  
Late Wisconsinan ◽  
Detrital Carbonate

Layers of ice-rafted, limestone debris rich sediment were deposited in the northwest Labrador Sea and the North Atlantic during the last glacial period (10-80 ka); these sediments were deposited by Heinrich events (H), events which record catastrophic collapses of the Laurentide Ice Sheet in the region of the Hudson Strait. These intervals of detrital carbonate rich sediments are referred to as detrital carbonate layers (DC) in the northwest Labrador Sea. Accelerator mass spectrometry (AMS) 14C dates provide a strong constraint on the timing for these events; H-1 = DC-1 and H-2 = DC-2. DC-0, also known as H-0, correlative to the Younger Dryas cooling event, is not as distinct a sediment unit in the northwest Labrador Sea as DC-1 and DC-2. An analysis of sediments from two cores (HU75009-IV-055 and HU75009-IV-056) off the mouth of the Hudson Strait in the northwest Labrador Sea basin sheds new light on the "missing" DC-0 sediment unit. Timing for the DC-0 event in cores 055 and 056 is bracketed between 11.3 ka ± 105 years and 10.4 ka ± 185 years based on AMS 14C dates. Sedimentology of the DC-0 unit reveals a sediment layer rich in ice-rafted debris with an increase in percentage of dolomite (representative material <2 mm), clay-size dolomite, and kaolinite; it is significantly different from DC-1 and DC-2 in the same analyzed cores. For example, the percent carbonate increase in DC-1 and DC-2 is approximately three to four times higher than that in DC-0. In addition, DC-1 and DC-2 show clear evidence for mass sediment transport processes which are not observed in DC-0. From these data, the DC-0 sediment unit in the northwest Labrador Sea records Cumberland Sound ice margin change and, for reasons addressed in this paper, the Hudson Strait does not play a major role in the deposition of DC-0 sediments at these core sites. Provenance indicators, such as kaolinite and dolomite, from the core study sediments corroborate this hypothesis. These results provide strong evidence for Cumberland Sound ice margin activity and sediment contribution during DC events, specifically DC-0, and additional evidence for multiple and synchronous ice margin change along the eastern Laurentide ice margin during the Late Wisconsinan, thus further supporting an atmospheric forcing mechanism for Late Wisconsinan ice sheet change.

Asynchronous instability of NE ice streams of the Laurentide Ice Sheet recorded in the marine sediments of Labrador Sea during the last glacial cycle

2020 ◽  
Author(s):  
Harunur Rashid ◽  
Mary Smith ◽  
Min Zeng ◽  
Yang Wang ◽  
Julie Drapeau ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Labrador Sea ◽  
Glacial Cycle ◽  
Ice Streams ◽  
Last Glacial ◽  
Ice Stream ◽  
Cumberland Sound ◽  
Detrital Carbonate ◽  
The Last Glacial

&lt;p&gt;Hughes et al. (1977) hypothesized of a pan-Arctic Ice Sheet that behaved as a single dynamic system during the Last Glacial Maximum. Moreover, the authors suggested a nearly grounded ice shelf in Davis Strait implying that little or no exchange between Baffin Island and the Labrador Sea. Here we present data at 1-cm (&lt;100 years) resolution between ~12 ka and 45 ka that shed light on the discharge from Hudson Strait and Lancaster Sound ice streams of the Late Pleistocene Laurentide Ice Sheet. A reference sediment core at 938 m water depth on the SE Baffin Slope was investigated with new oxygen isotope stratigraphy, X-ray fluorescence geochemistry, and 18 14C-AMS dates and correlated to 14 regional deep-water cores. Detrital carbonate-rich sediment layers H0-H4 were derived principally from Hudson Strait. Shortly after H2 and H3, the shelf-crossing Cumberland Sound ice stream supplied dark brown ice-proximal stratified sediments but no glacigenic debris-flow deposits. The counterparts of H3, H4, and (?)H5 events in the deep Labrador basin are 4&amp;#8211;10 m thick units of thin-bedded carbonate-rich mud turbidites from glacigenic debris flows on the Hudson Strait slope. The behavior of the Hudson Strait ice stream changed through the last glacial cycle. The Hudson Strait ice stream remained at the shelf break in H3-H5 but retreated rapidly across the shelf in H0-H2 and did not deglaciate Hudson Bay. During this time, Cumberland Sound ice twice reached the shelf edge. In H3&amp;#8211;H5, it remained at the shelf break long enough to supply thick turbidites. Minor supply of carbonate-rich sediment from Baffin Bay allows chronologic integration of the Baffin Bay and Labrador Sea detrital carbonate records, which is diachronous with respect to Heinrich events. The asynchrony of the carbonate events implies an open seaway through Davis Strait. Our data suggest that the maximum extent of ice streams in Hudson Strait, Cumberland Sound, and Lancaster Sound was neither synchronous.&lt;/p&gt;

scholarly journals Evidence for a hardwater radiocarbon dating effect, Wonder Lake, Denali national park and preserve, Alaska, U.S.A.

2002 ◽  
Vol 53 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Jonathan K. Child ◽  
Al Werner
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Pollen Record ◽  
Lake Area ◽  
Alaska Range ◽  
Radiocarbon Age ◽  
The North ◽  
Late Wisconsinan ◽  
Denali National Park ◽  
Age Estimates

Abstract Anderson et al. (1994) present a late Pleistocene/Holocene pollen record for lacustrine sediment cores retrieved from the north end of Wonder Lake, Denali National Park and Preserve, Alaska. Bulk radiocarbon age estimates obtained during their study suggest that either a Picea refugium persisted in the foothills of the north Alaska Range near Wonder Lake during the Late Wisconsinan, or that bulk radiocarbon age estimates are inaccurate. Subsequent cores recovered from Wonder Lake (and a near-by kettle pond) have been correlated to the Anderson et al. core and age dated using Atomic Mass Spectrometry (AMS) radiocarbon age estimates. AMS radiocarbon ages suggest that bulk radiocarbon ages from Anderson et al. (1994) are affected by hardwater conditions in Wonder Lake causing them to appear greater than 2000 14 C years too old. The corrected core chronology is consistent with documented regional vegetation changes during the glacial/interglacial transition and does not require a local Picea refugium in the Wonder Lake area during the Late Wisconsinan.

Late Quaternary Iceberg Rafting along the Antarctic Peninsula Continental Rise and in the Weddell and Scotia Seas

2001 ◽  
Vol 56 (3) ◽  
pp. 308-321 ◽  
Author(s):  
Colm Ó Cofaigh ◽  
Julian A. Dowdeswell ◽  
Carol J. Pudsey
Keyword(s):  
Antarctic Peninsula ◽  
Late Quaternary ◽  
Sediment Cores ◽  
Regional Scale ◽  
Ice Sheet ◽  
Glacial Cycles ◽  
Continental Rise ◽  
The North ◽  
Glacial Periods ◽  
The Antarctic

AbstractSediment cores from the continental rise west of the Antarctic Peninsula and the northern Weddell and Scotia Seas were investigated for their ice-rafted debris (IRD) content by lithofacies logging and counting of particles >0.2 cm from core x-radiographs. The objective of the study was to determine if there are iceberg-rafted units similar to the Heinrich layers of the North Atlantic that might record periodic, widespread catastrophic collapse of basins within the Antarctic Ice Sheet during the Quaternary. Cores from the Antarctic Peninsula margin contain prominent IRD-rich units, with maximum IRD concentrations in oxygen isotope stages 1, 5, and 7. However, the greater concentration of IRD in interglacial stages is the result of low sedimentation rates and current winnowing, rather than regional-scale episodes of increased iceberg rafting. This is also supported by markedly lower mass accumulation rates (MAR) during interglacial periods versus glacial periods. Furthermore, thinner IRD layers within isotope stages 2–4 and 6 cannot be correlated between individual cores along the margin. This implies that the ice sheet over the Antarctic Peninsula did not undergo widespread catastrophic collapse along its western margin during the late Quaternary (isotope stages 1–7). Sediment cores from the Weddell and Scotia Seas are characterized by low IRD concentrations throughout, and the IRD signal generally appears to be of limited regional significance with few strong peaks that can be correlated between cores. Tentatively, this argues against pervasive, rapid ice-sheet collapse around the Weddell embayment over the last few glacial cycles.

The Magnitude and Proximate Cause of Ice-Sheet Growth Since 35,000 yr B.P.

2001 ◽  
Vol 56 (3) ◽  
pp. 299-307 ◽  
Author(s):  
Isaac J. Winograd
Keyword(s):  
North Atlantic ◽  
Ice Sheet ◽  
Proximate Cause ◽  
Ice Volume ◽  
The North ◽  
Data Compilation ◽  
Sst Warming ◽  
Late Wisconsinan ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThe magnitude of late Wisconsinan (post-35,000 yr B.P.) ice-sheet growth in the Northern Hemisphere is not well known. Ice volume at ∼35,000 yr B.P. may have been as little as 20% or as much as 70% of the volume present at the last glacial maximum (LGM). A conservative evaluation of glacial–geologic, sea level, and benthic δ18O data indicates that ice volume at ∼35,000 yr B.P. was approximately 50% of that extant at the LGM (∼20,000 yr B.P.); that is, it doubled in about 15,000 yr. On the basis of literature for the North Atlantic and a sea-surface temperature (SST) data compilation, it appears that this rapid growth may have been forced by low-to-mid-latitude SST warming in both the Atlantic and Pacific Oceans, with attendant increased moisture transport to high latitudes. The SST ice-sheet growth notion also explains the apparent synchroneity of late Wisconsinan mountain glaciation in both hemispheres.

Late Quaternary (Stage 2 and 3) Meltwater and Heinrich Events, Northwest Labrador Sea

1994 ◽  
Vol 41 (1) ◽  
pp. 26-34 ◽  
Author(s):  
John T. Andrews ◽  
Helmut Erlenkeuser ◽  
Katherine Tedesco ◽  
Ali E. Aksu ◽  
A.J.Timothy Jull
Keyword(s):  
North Atlantic ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Labrador Sea ◽  
Near Surface ◽  
Heinrich Events ◽  
Eastern Margin ◽  
Detrital Carbonate

AbstractTwo major meltwater events are documented in cores from the NW Labrador Sea. One occurred ca. 20,000 14C yr B.P. in association with deposition of a major detrital carbonate unit. Both prior to and after this event, δ18O values of near-surface planktonic foraminifera were 4.5%, indicating fully enriched glacial values. A younger event (ca. 14,000 14 C yr B.P.) is characterized by a dramatic change in δ18O from 4.5 to 2.0% and coincided with the retreat of ice from the outer SE Baffin Shelf, possibly into Hudson Strait. These meltwater events coincide with Heinrich (H) layers 1 and 2 from North Atlantic sediments. The 14,000 14C yr B.P. meltwater event indicates that the eastern margin of the Laurentide Ice Sheet also underwent rapid retreat at approximately the same time as other ice sheet margins around the NE North Atlantic. A third major detrital carbonate event at the base of HU87-033-009, possibly correlative with Heinrich layer 3, occurred ca. 33,960 ± 675 14 C yr B.P.; however, this is older than the accepted date for H-3 of 27,000 14C yr B.P. and may be H-4.

Living at the margin of the retreating Fennoscandian Ice Sheet: The early Mesolithic sites at Aareavaara, northernmost Sweden

The Holocene ◽  
2012 ◽  
Vol 23 (1) ◽  
pp. 104-116 ◽  
Author(s):  
Per Möller ◽  
Olof Östlund ◽  
Lena Barnekow ◽  
Per Sandgren ◽  
Frida Palmbo ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Archaeological Site ◽  
Transitional Zone ◽  
North Coast ◽  
Small Scale ◽  
Archaeological Survey ◽  
The North ◽  
Ancylus Lake

During an archaeological survey in Pajala parish, northernmost Sweden, clusters of quartz waste from knapping and burnt bone were discovered on a glaciofluvial gravel plateau close to Aareavaara village in the Muonio River valley. Sampled materials from a larger area and small-scale excavations (in total 6 m2) are interpreted as resulting from short-stay hunter-gatherer camps. Radiocarbon dating on burnt bones suggest an age of occupancy at ~10,700 cal. yr BP, which is more or less contemporary with ‘Komsa Phase’ sites on the north coast of Norway (~300–360 km northwards). The Aareavaara site should thus be the oldest known archaeological site to date in northern Sweden. A palaeoenvironmental reconstruction, based on pollen analysis of sediment cores from two nearby lakes and radiocarbon dating of macrofossils for construction of time/depth sedimentation curves, suggests a deglaciation age of the area corresponding to occupation by early man (~10,700 cal. yr BP). Aareavaara was at the time of deglaciation situated in a transitional zone between subaqueous and subaerial ice-margin retreat from the northeast towards the southwest, with higher hills and plateaux forming an archipelago in the Ancylus Lake with highest shorelines formed at ~170 m a.s.l. The hunter-gatherer camp sites at Aareavaara were thus, both in time and space, located in close proximity to the retreating ice sheet margin, but also in a waterfront location, in fact on an island in the Ancylus Lake. Our pollen data suggest a subarctic birch woodland tundra landscape characterized by open vegetation, including occasional birch trees and an abundance of willow and dwarf birch.

Late Wisconsinan and Holocene history of southwestern Saskatchewan

1994 ◽  
Vol 31 (12) ◽  
pp. 1822-1837 ◽  
Author(s):  
Rudy W. Klassen
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Glacial Lakes ◽  
Grassland Vegetation ◽  
Southern Limit ◽  
Northern Margin ◽  
The North ◽  
Proglacial Lakes ◽  
History Of ◽  
Late Wisconsinan

The Late Wisconsinan Laurentide Ice Sheet reached the limit of glaciation along the north-facing slope of the unglaciated part of the Cypress Hills nunatak, but elsewhere around the Cypress Hills and Wood Mountain uplands of southwestern Saskatchewan it did not reach the limit of glaciation. An interval of deglaciation was followed by a readvance of the ice sheet, about 15 ka, to a position near the Late Wisconsinan limit, and was marked by strong flow of Keewatin ice from the north and weaker flow of Hudson ice from the northeast. Final deglaciation resulted in the formation of glacial lakes around the Cypress Hills nunatak. A network of ice-marginal and subglacial trenches, presently occupied by the Frenchman Valley and its tributaries, was formed when these lakes drained along, over, and under ice towards the western part of the Wood Mountain Upland to the east. The main trench joined an ancestral part of Frenchman Valley along the ice-free southern slopes of Wood Mountain Upland. Meltwater from the ice bordering the northern margin of the upland drained southward, excavating trenches across the highest parts of the upland and deepening ancestral valleys across the southern slopes. A succession of proglacial lakes fronted parts of the ice margin as it retreated downslope to the north. The area was deglaciated about 13.5 ka. The southern limit of a north to south forest–grassland transition was established by 13 ka along the regional drainage divide across the study area. Prairie grassland vegetation covered the southern slopes of the uplands and forests of deciduous and coniferous trees covered the highest parts of uplands and drift-mantled parts of the continental glacier to the north. The belt of forest–grassland transition had shifted well to the north of the study area by 9 ka, and a climate that was warmer and drier than at present continued to about 5 ka, when conditions became somewhat cooler.

scholarly journals An Interpretation of Late Quaternary Glacial Flow Indicators in the Baie des Chaleurs Region, Northern New Brunswick

2007 ◽  
Vol 43 (2) ◽  
pp. 179-190 ◽  
Author(s):  
A. G. Pronk ◽  
P. T. Bobrowsky ◽  
M. A. Parkhill
Keyword(s):  
New Brunswick ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Field Research ◽  
Published Data ◽  
Second Phase ◽  
Sedimentary Deposits ◽  
The North ◽  
Third Phase ◽  
Late Wisconsinan

ABSTRACT A sequence of late Quaternary geologic events in northern New Brunswick is determined from striation analysis derived from published data, open file reports, and field research conducted by the authors since 1985. These data are integrated with clast provenance and clast fabric trend analysis, as well as information from other studies in the surrounding area. South of the Baie des Chaleurs, a complicated Late Wisconsinan glacial history is preserved in the form of erosive features including nailhead striae, miniature crag-and-tails, and various scars, striations, and fractures. The rarity of sedimentary deposits and datable materials precludes simple stratigraphie interpretation. Based on over 1,000 striation sites, we conclude four major phases of glacial flow affected the area during the Late Wisconsinan: 1) an early flow to the southeast which reflects local Appalachian ice; 2) a second phase of glacial flow to the east indicating a Laurentide ice influence in western New Brunswick; 3) a third phase of glacial flow to the north-northeast, which may represent ice response to drawdown in the Baie des Chaleurs; and 4) a final multidirectional flow indicating localized ice response during the last stages of Late Wisconsinan glaciation. The absence of Canadian Shield erratics in northern New Brunswick is explained in terms of ice streaming along the St. Lawrence channel beneath a southward-flowing Laurentide Ice Sheet. Basal ice debris (including Shield erratics) was apparently truncated and removed by the obliquely flowing ice stream, leaving relatively clean ice in the Ice Sheet as it entered Gaspésie and ultimately New Brunswick.

Sediments, sedimentation rates, and environments, southeast Baffin Shelf and northwest Labrador Sea, 8–26 ka

1994 ◽  
Vol 31 (1) ◽  
pp. 90-103 ◽  
Author(s):  
J. T. Andrews ◽  
K. Tedesco ◽  
W. M. Briggs ◽  
L. W. Evans
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Planktonic Foraminifera ◽  
Ice Sheet ◽  
Shelf Break ◽  
Laurentide Ice Sheet ◽  
Labrador Sea ◽  
Baffin Island ◽  
Near Surface ◽  
Detrital Carbonate

Ten 14C-dated cores are described from the Labrador Sea, continental slope, and Hatton and Resolution basins on the southeast Baffin Shelf. Based on sharply defined detrital carbonate layers in the Labrador Sea cores, we propose that the Laurentide Ice Sheet reached the shelf break at both 20 and 15 14C ka (24.3 and 18.2 sidereal ka) and contributed significant sediment to the northwest Labrador Sea both times; the flux was ± 720 kg/(m2∙ka) during these periods of maximum ice extent. The Laurentide Ice Sheet retreated from its 15 ka position at the shelf break to the inner shelf between 14 and 12 14C ka. Ice-proximal conditions, recognized by relatively light δ18O on near-surface planktonic foraminifera, high detrital carbonate, and benthic foraminiferal faunas (dominated by Elphidium excavatum forma clavata; Cassidulina reniforme), prevailed until at least 10 14C ka. The ice readvanced toward Resolution Basin and across part of Hatton Basin at 11 14C ka. Accelerator mass spectrometry dates on core tops indicate that deposition on the shelf virtually ceased by 7 ka and was very low in the northwest Labrador Sea throughout the Holocene. Downcore accelerator mass spectrometry dates indicate that during deglaciation, the loci of depocentres shifted in response to changes in the position of the ice margin. On the southeast Baffin Island shelf net sediment fluxes at the sea floor reached values of over 3000 kg/(m2∙ka) between 12 and 10 14C ka, of which nearly half was detrital carbonate, principally calcite.

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