Late Quaternary sedimentation in central Flemish Pass

1992 ◽  
Vol 29 (3) ◽  
pp. 535-550 ◽  
Author(s):  
David J. W. Piper ◽  
Christopher P. G. Pereira
Keyword(s):  
Late Quaternary ◽  
Ice Sheets ◽  
Seismic Profiles ◽  
Grand Banks ◽  
The Past ◽  
Labrador Current ◽  
Lithostratigraphic Units ◽  
History Of ◽  
Quaternary History ◽  
Late Wisconsinan

Flemish Pass is a basin in 1000 m water depth on the continental slope off the Grand Banks of Newfoundland and has a Quaternary fill principally of turbidites. The late Quaternary history of the pass has been investigated using mid-range side-scan sonargraphs, high-resolution seismic profiles, and cores dated using C-14. The sequence of facies in the cores reveals six lithostratigraphic units deposited in the past 40 ka. At 15–19 ka and ?25–30 ka, sedimentation was dominated by debris-flow and turbidite deposits, together with hemipelagic deposits of similar clay-size mineralogy, derived from the Grand Banks. At other times, ice-rafting and hemipelagic sedimentation, principally of carbonate-rich sediment transported by the Labrador Current, predominated. A late Quaternary regional unconformity on the slope may reflect the effects of ice sheets reaching the shelf break, probably in the Early Wisconsinan. Late Wisconsinan resedimentation was not related to ice-marginal processes and probably resulted from iceberg impacts.

Late Quaternary History of Tundra Vegetation in Northwestern Alaska

1994 ◽  
Vol 41 (3) ◽  
pp. 306-315 ◽  
Author(s):  
Patricia M. Anderson ◽  
Patrick J. Bartlein ◽  
Linda B. Brubaker
Keyword(s):  
Vegetation Type ◽  
Late Quaternary ◽  
Vegetation Types ◽  
The Past ◽  
Modern Pollen ◽  
Qualitative Approaches ◽  
Tundra Vegetation ◽  
Shrub Tundra ◽  
History Of ◽  
Quaternary History

AbstractPollen analysis of a new core from Joe Lake indicates that the late Quaternary vegetation of northwestern Alaska was characterized by four tundra and two forest-tundra types. These vegetation types were differentiated by combining quantitative comparisons of fossil and modern pollen assemblages with traditional, qualitative approaches for inferring past vegetation, such as the use of indicator species. Although imprecisely dated, the core probably spans at least the past 40,000 yr. A graminoid-Salix tundra dominated during the later and early portions of the glacial record. The middle glacial interval and the transition from glacial to interglacial conditions are characterized by a graminoid-Betula-Salix tundra. A Populus forest-Betula shrub tundra existed during the middle potion of this transition, being replaced in the early Holocene by a Betula-Alnus shrub tundra. The modern Picea forest-shrub tundra was established by the middle Holocene. These results suggest that the composition of modem tundra communities in northwestern Alaska developed relatively recently and that throughout much of the late Quaternary, tundra communities were unlike the predominant types found today in northern North America. Although descriptions of vegetation variations within the tundra will always be restricted by the innate taxonomic limitations of their herb-dominated pollen spectra, the application of multiple interpretive approaches improves the ability to reconstruct the historical development of this vegetation type.

Late Quaternary history of contourite drifts and variations in Labrador Current flow, Flemish Pass, offshore eastern Canada

2014 ◽  
Vol 34 (5) ◽  
pp. 457-470 ◽  
Author(s):  
Nicole R. Marshall ◽  
David J. W. Piper ◽  
Francky Saint-Ange ◽  
D. Calvin Campbell
Keyword(s):  
Current Flow ◽  
Late Quaternary ◽  
Eastern Canada ◽  
Contourite Drifts ◽  
Labrador Current ◽  
History Of ◽  
Quaternary History

Late Quaternary history of black spruce and grasslands in southwest Yukon Territory

1992 ◽  
Vol 70 (7) ◽  
pp. 1336-1345 ◽  
Author(s):  
T. J. Keenan ◽  
L. C. Cwynar
Keyword(s):  
Dominant Species ◽  
Black Spruce ◽  
Late Quaternary ◽  
Minor Component ◽  
White Spruce ◽  
Yukon Territory ◽  
The Past ◽  
History Of ◽  
Quaternary History ◽  
A Minor

Pollen records from Long Last Lake and Two Horsemen Pond, near the centre of the arid region of southwest Yukon Territory, do not support the hypotheses that (i) black spruce was a dominant species in the region and (ii) the southwest Yukon supported widespread grasslands during most of the past 10 000 years. Black spruce became established between 8500 and 8000 BP, shortly after the arrival of white spruce, but its low pollen percentages (< 5%) indicate that it was a minor component of forests. Between 6000 and 5000 BP, white spruce populations decreased as black spruce and green alder increased, but black spruce remained a minor constituent of the forest, never becoming a dominant species as at Kettlehole Pond near the southeast margin of the arid southwest Yukon. The initial vegetation was a poplar woodland, dating from 9200 to 8500 BP at Long Last Lake. At both Long Last Lake and Two Horsemen Pond, the high percentages of herb pollen indicate that the forest was open, but the low values of grass pollen suggest that grasslands were not extensive. Coincident with the establishment of spruce woodland at 8500 BP, pollen of herbs declines and remains comparatively low until 1300 BP when herbs, including grasses, increase to maximum values for the period of record, indicating the grassland communities were probably never more abundant during the Holocene than they are now. Key words: southwest Yukon, black spruce, pollen analysis, paleoecology, climate change.

Holocene ice fluctuations on Brabant Island, Antarctic Peninsula

1989 ◽  
Vol 1 (2) ◽  
pp. 165-166 ◽  
Author(s):  
J.D. Hansom ◽  
C.P. Flint
Keyword(s):  
Antarctic Peninsula ◽  
Late Quaternary ◽  
Ice Sheets ◽  
West Antarctica ◽  
Scotia Sea ◽  
Glacial Chronology ◽  
Subantarctic Islands ◽  
History Of ◽  
Quaternary History ◽  
The Antarctic

Recent geomorphological research in the ice-free areas of West Antarctica and the subantarctic islands has begun to provide an outline glacial chronology that helps our understanding of the late Quaternary history of ice sheets. However, there is a need for detailed studies of the glacial history of the Antarctic Peninsula area and its offshore islands before a general chronology can be fully reliable. In particular, evidence of Neoglacial glacial fluctuations in the area are imperfectly known in spite of work by Sugden & Clapperton (1977) on island groups in the Scotia Sea, Clapperton et al. (1978) on South Georgiaand Clapperton & Sugden (1982) on Alexander Island. The aim of this note is to present data relating to Holocene glacier fluctuations from the hitherto unstuded Brabant Island (64°15′S, 62°3′W).

Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

1992 ◽  
Vol 29 (2) ◽  
pp. 222-235 ◽  
Author(s):  
E. H. Cumming ◽  
A. E. Aksu ◽  
P. J. Mudie
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Seismic Profiles ◽  
Ice Shelf ◽  
Acoustic Basement ◽  
Fine Grained ◽  
History Of ◽  
Lift Off ◽  
Late Wisconsinan ◽  
Basal Till

High-resolution seismic profiles and core data from Bonavista Bay, northeast Newfoundland, show that the sedimentary package above acoustic basement was deposited during the deglaciation of the Late Wisconsinan ice sheet. During the Late Wisconsinan maximum (~ 20 000 BP), Bonavista Bay was occupied by a grounded ice sheet that extended farther offshore. Deglaciation of the bay was rapid and occurred prior to ~ 13 500 BP during a time of rising sea level. A basal till was deposited beneath the grounded ice, and after lift-off an ice shelf developed over the outer basins where diamicton was deposited. The inner bay gradually deglaciated as the ice margin retreated to the present-day shoreline by ~ 13 000 BP, and fine-grained outwash sediments transported by interflows were rapidly deposited. The inner bay remained under the influence of one or more remnant ice centres until ~ 10 000 BP, with ice positioned on the Bonavista and Gander peninsulas. Normal marine conditions were established in the outer bay by ~ 13 500 BP and in the inner bay and fjords by ~ 10 000 BP.

Late Wisconsinan glacial stratigraphy and history of southeastern Manitoba

1980 ◽  
Vol 17 (1) ◽  
pp. 19-35 ◽  
Author(s):  
James T. Teller ◽  
Mark M. Fenton
Keyword(s):  
Carbonate Rocks ◽  
Lacustrine Sediment ◽  
Precambrian Rock ◽  
Lake Agassiz ◽  
Rock Fragments ◽  
Lithostratigraphic Units ◽  
Stratigraphic Position ◽  
History Of ◽  
International Boundary ◽  
Late Wisconsinan

The history of Late Wisconsinan glaciation in southwestern Manitoba has been established by identifying and correlating ice-laid lithostratigraphic units in the subsurface. Five Late Wisconsinan tills are defined on the basis of their texture, mineralogic composition, and stratigraphic position. These new formations are, from youngest to oldest, Marchand, Whitemouth Lake, Roseau, Senkiw, and Whiteshell Formations.Late Wisconsinan ice first invaded southeastern Manitoba 22 000 to 24 000 years ago. This Laurentide glacier advanced from the northeast across the Precambrian Shield and deposited the sandy Whiteshell and Senkiw tills, which contain abundant Precambrian rock fragments and minerals and few Paleozoic carbonate grains. Shortly after this, Keewatin ice advanced from the northwest over Paleozoic carbonate rocks, depositing the loamy carbonate-rich Roseau Formation throughout most of the area. This ice remained over southeastern Manitoba until after 13 500 years ago, when it rapidly retreated northward with Lake Agassiz on its heels. Two brief glacial readvances occurred. The first overrode Lake Agassiz lacustrine sediment as far south as central North Dakota shortly after about 13 000 years ago. The clayey Whitemouth Lake till was deposited in southern Manitoba at this time. After a rapid retreat, the ice briefly pushed southward over southeastern Manitoba about 12 000 years ago to just south of the International Boundary. The sandy carbonate-rich Marchand Formation was deposited at this time as the ice overrode its own sandy outwash. By 11 000 years ago, ice had disappeared from southeastern Manitoba.

Late Quaternary history of colluvial deposition and erosion in hollows, central California Coast Ranges

1990 ◽  
Vol 102 (7) ◽  
pp. 969-982 ◽  
Author(s):  
STEVEN L. RENEAU ◽  
WILLIAM E. DIETRICH ◽  
DOUGLAS J. DONAHUE ◽  
A. J. TIMOTHY JULL ◽  
MEYER RUBIN
Keyword(s):  
Late Quaternary ◽  
California Coast ◽  
Central California ◽  
History Of ◽  
Quaternary History ◽  
Coast Ranges ◽  
California Coast Ranges

scholarly journals Plio-Quaternary history of the Turkish coastal zone of the Enez-Evros Delta: NE Aegean Sea

2001 ◽  
Vol 2 (2) ◽  
pp. 95 ◽  
Author(s):  
B. ALPAR
Keyword(s):  
Late Pleistocene ◽  
Sand Dunes ◽  
Aegean Sea ◽  
Interglacial Period ◽  
Shelf Area ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Alluvial Deposits ◽  
History Of ◽  
Quaternary History

The Enez-Evros Delta, NE Aegean Sea, is located in one the most important wetlands in the world with its sandy offshore islands, abandoned channel mouths, sand-dunes, shoals, marshlands, saline lagoons and saltpans. It comprises very well developed sedimentary units and a prodelta lying on an older submarine delta. The present day elevations of the middle-late Pleistocene marine terraces indicate a regional tectonic uplift in the area. Due to lack of geophysical and bore hole data and partly due to its strategic position, the structural and stratigraphic features of the submarine extension of the delta are not known in detail. In this paper, Plio-Quaternary history of this delta and its submarine part on the Turkish shelf was explored by using high-resolution shallow reflection seismic profiles. The delta is formed by the alluvial deposits of the Enez-Evros River and shaped by their interaction with the sea. It takes place in front of a large and protected ancient bay which was filled rapidly over millennia. The sediments in the plateau off the river are principally pro-deltaic with muddy areas near the river mouths changing to muddy sand further out. The sea-level changes in Plio-Quaternary were characterised by three different seismic stratigraphic units on the folded Miocene limestone basement. In the late Pleistocene, the shelf area over an Upper Miocene basement was flooded during the Riss-Würm interglacial period, exposed in the Würm glacial stage, and flooded once again during the Holocene transgression.

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