Spatial patterns of modern diatom distribution and multiple paleolimnological records from a small arctic lake on Baffin Island, Arctic Canada

1996 ◽  
Vol 74 (3) ◽  
pp. 435-449 ◽  
Author(s):  
Alexander P. Wolfe
Keyword(s):  
Late Holocene ◽  
Baffin Island ◽  
Diatom Assemblages ◽  
Arctic Canada ◽  
Habitat Specificity ◽  
Radiocarbon Dates ◽  
Numerous Species ◽  
Sediment Reworking ◽  
Clear Differentiation ◽  
Lake Ontogeny

The assumption that within-lake, deep-water sedimentary diatom assemblages are relatively uniform and that a single core is sufficient to depict lake ontogeny was tested for a small tarn on the southwestern Cumberland Peninsula of Baffin Island, Northwest Territories. Diatom transport and deposition were evaluated through analyses of periphytic, planktonic, and epipelic habitats. Diatom stratigraphies of four cores were used to test whether or not trends are comparable in different regions of the lake and throughout the Holocene. Among 12 surface-sediment stations, diatom distributions were alternately highly equitable or variable. Valves of evenly distributed genera (Aulacoseira and Achnanthes) are mixed in the water column prior to deposition. This is supported by plankton tow and periphyton samples, which were respectively dominated by Aulacoseira distans (and varieties) and Achnanthes altaica. Conversely, frequencies of several benthic taxa (e.g., Pinnularia biceps, species of Eunotia) varied up to 30% between stations, in patterns unrelated to water depth, and reflecting habitat specificity and minimal transport prior to burial. Of the four cores (38.0–95.5 cm), analysis of the two longest revealed three distinct zones: (i) a zone dominated by species of Fragilaria (> 9000 BP); (ii) a zone containing benthic acidophilic diatoms indicating natural acidification (9000–7000 BP); and (iii) a zone characterized by numerous species of Aulacoseira ranging from the mid to late Holocene. Clear differentiation of the lower two zones was impossible in the shorter cores, and radiocarbon dates suggest that sediment reworking truncated the earliest records of organic sedimentation at these sites. Correspondence analysis facilitated comparisons of the diatom stratigraphies and enabled the evaluation of core reproducibility. Central cores preserve the most useful paleolimnological records in this environment. Keywords: diatoms, paleolimnology, Arctic Canada, Baffin Island.

Late Holocene diatom biostratigraphy and sea-level changes in the southeastern Beaufort Sea

2000 ◽  
Vol 37 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Stéphane Campeau ◽  
Arnaud Héquette ◽  
Reinhard Pienitz
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Beaufort Sea ◽  
Sea Level Changes ◽  
Diatom Assemblages ◽  
Radiocarbon Dates ◽  
Sea Levels ◽  
Temporal Precision ◽  
Level Change ◽  
Paleoenvironmental Changes

Late Holocene sediments from the Atkinson Point area were analysed to provide quantitative reconstructions of recent sea-level changes in the southeastern Beaufort Sea. The succession of diatom assemblages in five cores revealed paleoenvironmental changes induced by the transgression of the Beaufort Sea during successive periods of lacustrine conditions, breaching and flooding of thermokarst lakes by the sea, and the landward migration of sandy spits. Based on radiocarbon dates and quantitative paleodepth determinations, a relative sea-level curve for the late Holocene has been developed. Despite a loss of temporal precision due to old carbon contamination, an envelope of sea-level change has been defined for the last 2 ka BP, suggesting a sea-level rise in the order of 1.1 mm a-1 for the last millennium. This paper presents the first sea-level reconstruction inferred from a diatom-based transfer function. It represents an improvement over traditional methods which were limited to qualitative estimates of past sea levels.

Neoglacial ice expansion and late Holocene cold-based ice cap dynamics on Cumberland Peninsula, Baffin Island, Arctic Canada

2014 ◽  
Vol 91 ◽  
pp. 242-256 ◽  
Author(s):  
Annina Margreth ◽  
Arthur S. Dyke ◽  
John C. Gosse ◽  
Alice M. Telka
Keyword(s):  
Late Holocene ◽  
Baffin Island ◽  
Arctic Canada ◽  
Ice Cap

Studies of glacial history in Arctic Canada. I. Pumice, radiocarbon dates, and differential postglacial uplift in the eastern Queen Elizabeth Islands

1970 ◽  
Vol 7 (2) ◽  
pp. 634-664 ◽  
Author(s):  
Weston Blake Jr.
Keyword(s):  
Source Area ◽  
Ellesmere Island ◽  
Northern Europe ◽  
Baffin Island ◽  
Arctic Canada ◽  
Radiocarbon Dates ◽  
Time Line ◽  
Devon Island ◽  
Last Glaciation ◽  
Raised Beaches

Dark brown pumice has been discovered recently on raised beaches of Ellesmere and Devon Islands, and in archeological sites on Baffin Island. It is similar in appearance and chemical composition to pumice associated with raised marine features throughout northern Europe, especially along the coasts of Norway and Spitsbergen. The source area for the pumice is uncertain, but Iceland is a good possibility.Radiocarbon dates on driftwood and whale bones imbedded in beaches at the "pumice level", as well as at higher and lower elevations, indicate that the pumice arrived approximately 5000 years ago.The pumice serves as a time-line and provides a means of correlating widely-separated marine features. Because these features now occur at different elevations, the amount and direction of tilt can be calculated. Also, former ice centers can be delineated, as the areas which have undergone the greatest uplift are those where the ice cover was once thickest. In Arctic Canada the "pumice level" rises westward along Jones Sound—from 16.5 m a.s.l. at the mouth of South Cape Fiord, Ellesmere Island, to 24.0 m at the eastern tip of Colin Archer Peninsula, Devon Island, ca. 130 km away. It also rises northwestward toward the head of South Cape Fiord.The Jones Sound information, plus radiocarbon dates from elsewhere in the Queen Elizabeth Islands indicating the approximate position of the shoreline at the same time, shows that there is a region in the eastern and central part of the archipelago where >25 m of uplift has occurred during the last 5000 years. This region, including considerable areas that are now sea, is believed to have been covered by a major ice sheet during the last glaciation.

The last interglacial–glacial cycle, Clyde foreland, Baffin Island, N.W.T.: stratigraphy, biostratigraphy, and chronology

1977 ◽  
Vol 14 (12) ◽  
pp. 2824-2857 ◽  
Author(s):  
G. H. Miller ◽  
J. T. Andrews ◽  
S. K. Short
Keyword(s):  
Amino Acid ◽  
Marine Sediments ◽  
Baffin Island ◽  
Buried Soils ◽  
Last Interglacial ◽  
Pollen Assemblage ◽  
Outlet Glacier ◽  
Radiocarbon Dates ◽  
Last Glaciation

A study of the stratigraphic sequence (14C and amino acid age control), marine bivalve faunal changes, and palynology of buried soils and organic-rich sediment collected from the Clyde Foreland Formation in the extensive cliff sections of the Clyde foreland, eastern Baffin Island, N.W.T., suggests the following last interglacial – Foxe (last glaciation) glacial – present interglacial sequence.(1) Cape Christian Member (ca. 130 000 years BP?)Consists of the Sledgepointer till overlain by the Cape Christian marine sediments. In situ molluscan fauna, collected from the marine sediments, contain a moderately warm bivalve assemblage. A well-developed soil that formed on the marine sediments (Cape Christian soil) contains an interglacial pollen assemblage dominated by dwarf birch. U-series dates of > 115 000 and ca. 130 000 years BP on molluscs from the Cape Christian marine sediments suggest that they were deposited during the last interglaciation, here termed the Cape Christian Interglaciation. The development of a subarctic pollen assemblage in the Cape Christian soil has not been duplicated during the present interglaciation, suggesting higher summer temperatures and perhaps a duration well in excess of 10 000 years for the last interglaciation.(2) Kuvinilk MemberConsists of fossiliferous marine sediments, locally divided by the Clyde till into upper and lower units. The Clyde till was deposited by the earliest and most extensive advance of the Foxe (last) Glaciation. Kuvinilk marine sediments both under- and overlying the Clyde till contain the pecten Chlamys islandicus, indicating that the outlet glacier advanced into a subarctic marine environment. Amino acid ratios from in situ pelecypod shells abovę and below the Clyde till are not statistically different, but contrast markedly with ratios obtained from the same species in the Cape Christian Member. Organic horizons within the Kuvinilk marine sediments contain a relatively rich pollen assemblage, although 'absolute' counts are low.(3) Kogalu Member (> 35 00014C years BP)Sediments of the Kogalu Member unconformably overlie those of the Kuvinilk Member, but are of a similar character. The dominant sediments are marine in origin, but in places are divided into upper and lower units by the Ayr Lake till. Amino acid ratios from in situ shells above and below the Ayr Lake till are indistinguishable, but substantially less than those in the Kuvinilk Member, suggesting the two members are separated by a considerable time interval. Radiocarbon dates on shells in the Kogalu marine sediments range from 33 000 to 47 700 years BP, but these may be only minimum estimates. The sea transgressed to a maximum level 70–80 m asl, coincident with the glacial maximum. Subarctic marine fauna of interstadial–interglacial character occur within the Kogalu marine sediments.(4) Eglinton Member (10 000 years BP to present)A major unconformity exists between the Kogalu and Eglinton Members. Ravenscraig marine sediments were deposited during an early Holocene marine transgression–regression cycle; the oldest dates on these sediments are ca. 10 000 years BP. Locally a vegetation mat occurs at the base or within the Ravenscraig unit. Pollen from these beds is sparse, but indicates a terrestrial vegetation assemblage as diverse as that of today. There is no evidence that Laurentide Ice reached the foreland during the last 30 000 years. Eolian sands that overlie a soil developed on the marine sediments record a late Holocene climatic deterioration. Pollen in organic-rich sediments at the base of, and within, the eolian sands record a vegetation shift in response to climatic change.

Late Holocene Glacier Fluctuations and Vegetation Changes at Maktak Fiord, Baffin Island, N.W.T., Canada

1976 ◽  
Vol 8 (4) ◽  
pp. 343 ◽  
Author(s):  
G. S. Boulton ◽  
J. H. Dickson ◽  
H. Nichols ◽  
M. Nichols ◽  
S. K. Short
Keyword(s):  
Late Holocene ◽  
Vegetation Changes ◽  
Baffin Island ◽  
Glacier Fluctuations

scholarly journals The source of topography across the Cumberland Peninsula, Baffin Island, Arctic Canada: differential exhumation of a North Atlantic rift flank

2019 ◽  
Vol 176 (6) ◽  
pp. 1093-1106 ◽  
Author(s):  
Scott Jess ◽  
Randell Stephenson ◽  
Søren B. Nielsen ◽  
Roderick Brown
Keyword(s):  
North Atlantic ◽  
Baffin Island ◽  
Arctic Canada

scholarly journals Late Holocene landscape change history related to the Alpine Fault determined from drowned forests in Lake Poerua, Westland, New Zealand

2012 ◽  
Vol 12 (6) ◽  
pp. 2051-2064 ◽  
Author(s):  
R. M. Langridge ◽  
R. Basili ◽  
L. Basher ◽  
A. P. Wells
Keyword(s):  
Lake Level ◽  
Late Holocene ◽  
Alluvial Fan ◽  
Time Of Death ◽  
Fault Rupture ◽  
Radiocarbon Dates ◽  
Living Tree ◽  
Alpine Fault ◽  
History Of ◽  
Lowland Forests

Abstract. Lake Poerua is a small, shallow lake that abuts the scarp of the Alpine Fault on the West Coast of New Zealand's South Island. Radiocarbon dates from drowned podocarp trees on the lake floor, a sediment core from a rangefront alluvial fan, and living tree ring ages have been used to deduce the late Holocene history of the lake. Remnant drowned stumps of kahikatea (Dacrycarpus dacrydioides) at 1.7–1.9 m water depth yield a preferred time-of-death age at 1766–1807 AD, while a dryland podocarp and kahikatea stumps at 2.4–2.6 m yield preferred time-of-death ages of ca. 1459–1626 AD. These age ranges are matched to, but offset from, the timings of Alpine Fault rupture events at ca. 1717 AD, and either ca. 1615 or 1430 AD. Alluvial fan detritus dated from a core into the toe of a rangefront alluvial fan, at an equivalent depth to the maximum depth of the modern lake (6.7 m), yields a calibrated age of AD 1223–1413. This age is similar to the timing of an earlier Alpine Fault rupture event at ca. 1230 AD ± 50 yr. Kahikatea trees growing on rangefront fans give ages of up to 270 yr, which is consistent with alluvial fan aggradation following the 1717 AD earthquake. The elevation levels of the lake and fan imply a causal and chronological link between lake-level rise and Alpine Fault rupture. The results of this study suggest that the growth of large, coalescing alluvial fans (Dry and Evans Creek fans) originating from landslides within the rangefront of the Alpine Fault and the rise in the level of Lake Poerua may occur within a decade or so of large Alpine Fault earthquakes that rupture adjacent to this area. These rises have in turn drowned lowland forests that fringed the lake. Radiocarbon chronologies built using OxCal show that a series of massive landscape changes beginning with fault rupture, followed by landsliding, fan sedimentation and lake expansion. However, drowned Kahikatea trees may be poor candidates for intimately dating these events, as they may be able to tolerate water for several decades after metre-scale lake level rises have occurred.

scholarly journals Pollen-inferred regional vegetation patterns and demographic change in Southern Anatolia through the Holocene

The Holocene ◽  
2019 ◽  
Vol 29 (5) ◽  
pp. 728-741 ◽  
Author(s):  
Jessie Woodbridge ◽  
C Neil Roberts ◽  
Alessio Palmisano ◽  
Andrew Bevan ◽  
Stephen Shennan ◽  
...  
Keyword(s):  
Demographic Change ◽  
Late Holocene ◽  
Vegetation Change ◽  
Anthropogenic Activities ◽  
Population Expansion ◽  
Ecological Systems ◽  
Archaeological Sites ◽  
Radiocarbon Dates ◽  
Significant Area ◽  
The Mediterranean

Southern Anatolia is a highly significant area within the Mediterranean, particularly in terms of understanding how agriculture moved into Europe from neighbouring regions. This study uses pollen, palaeoclimate and archaeological evidence to investigate the relationships between demography and vegetation change, and to explore how the development of agriculture varied spatially. Data from 21 fossil pollen records have been transformed into forested, parkland and open vegetation types using cluster analysis. Patterns of change have been explored using non-metric multidimensional scaling (nMDS) and through analysis of indicator groups, such as an Anthropogenic Pollen Index, and Simpson’s Diversity. Settlement data, which indicate population densities, and summed radiocarbon dates for archaeological sites have been used as a proxy for demographic change. The pollen and archaeological records confirm that farming can be detected earlier in Anatolia in comparison with many other parts of the Mediterranean. Dynamics of change in grazing indicators and the OJCV ( Olea, Juglans, Castanea and Vitis) index for cultivated trees appear to match cycles of population expansion and decline. Vegetation and land use change is also influenced by other factors, such as climate change. Investigating the early impacts of anthropogenic activities (e.g. woodcutting, animal herding, the use of fire and agriculture) is key to understanding how societies have modified the environment since the mid–late Holocene, despite the capacity of ecological systems to absorb recurrent disturbances. The results of this study suggest that shifting human population dynamics played an important role in shaping land cover in central and southern Anatolia.

scholarly journals Middle Dorset Communal Structures on Victoria Island

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
T. Max Friesen
Keyword(s):  
Arctic Canada ◽  
Radiocarbon Dates ◽  
Victoria Island

AbstractThis paper describes a cluster of large communal structures in the Oxford Bay region of southeastern Victoria Island in Nunavut, Arctic Canada. The structures consist of linear stone outlines of up to 24 meters in length, and resemble the relatively well-documented Late Dorset longhouses which have been found across much of the Eastern Arctic. However, radiocarbon dates indicate that the Oxford Bay structures were built and used from roughly 200 to 600-700 cal AD, placing them in the Middle Dorset period. Elsewhere, Middle Dorset communal structures are rare, making the Oxford Bay phenomenon unique. The sites are interpreted as resulting from population aggregations associated with the fall caribou hunt, and may represent direct predecessors of the more widespread Late Dorset longhouses.

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