Glacial dynamics and deglaciation history of Hambergbukta reconstructed from submarine landforms and sediment cores, SE Spitsbergen, Svalbard

Boreas ◽  
2020 ◽  
Author(s):  
Riko Noormets ◽  
Anne Flink ◽  
Nina Kirchner
Keyword(s):  
Sediment Cores ◽  
History Of ◽  
Glacial Dynamics ◽  
Submarine Landforms

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

The History of Human Impacts in the Clear Lake Watershed ( California) as Deduced from Lake Sediment Cores*

1999 ◽  
Author(s):  
Douglas Nelson ◽  
Alan Heyvaert ◽  
Laurent Meillier ◽  
Jae Kim ◽  
Xiaoping Li ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Human Impacts ◽  
Sediment Cores ◽  
Clear Lake ◽  
History Of

Penguin occupation in the Vestfold Hills

2008 ◽  
Vol 21 (2) ◽  
pp. 131-134 ◽  
Author(s):  
Tao Huang ◽  
Liguang Sun ◽  
Yuhong Wang ◽  
Renbin Zhu
Keyword(s):  
Sediment Core ◽  
Environmental Changes ◽  
Sediment Cores ◽  
East Antarctica ◽  
Before Present ◽  
The Holocene ◽  
History Of ◽  
Vestfold Hills ◽  
Free Area ◽  
Ornithogenic Sediment

AbstractDuring CHINARE-22 (December 2005–March 2006), we investigated six penguin colonies in the Vestfold Hills, East Antarctica, and collected several penguin ornithogenic sediment cores, samples of fresh guano and modern penguin bone and feather. We selected seven penguin bones and feathers and six sediments from the longest sediment core and performed AMS14C dating. The results indicate that penguins occupied the Vestfold Hills as early as 8500 calibrated years before present (cal. yrbp), following local deglaciation and the formation of the ice free area. This is the first report on the Holocene history of penguins in the Vestfold Hills. As in other areas of Antarctica, penguins occupied this area as soon as local ice retreated and the ice free area formed, and they are very sensitive to climatic and environmental changes. This work provides the foundation for understanding the history of penguins occupation in Vestfold Hills, East Antarctica.

Late Quaternary sedimentation on the southwestern Scotian Slope, eastern Canada: relationship to glaciationGeological Survey of Canada Contribution 20070176.

2008 ◽  
Vol 45 (3) ◽  
pp. 267-285 ◽  
Author(s):  
Thian Hundert ◽  
David J.W. Piper
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Sediment Supply ◽  
Scotian Shelf ◽  
Eastern Canada ◽  
Glacial Retreat ◽  
Air Gun ◽  
Continental Slopes ◽  
History Of ◽  
Seismic Reflection Profiles

The sedimentary record on continental slopes has the potential to preserve a record of glacial retreat on the adjacent continental shelf. The glacial history of the southwestern part of the Scotian Shelf is poorly known. Air-gun and high-resolution sparker profiles and numerous sediment cores up to 10 m long have been used to determine the character of sedimentation on the southwestern Scotian Slope since the last glacial maximum (LGM). Seismic-reflection profiles show that glacial till was deposited at shallow depths on the upper continental slope, and correlation to dated piston cores farther downslope show that this till dates from the LGM. Slope sedimentation at this time was dominated by local ice and deposited as plume fallout and turbidites. Progressively increasing importance of red-brown sediment derived from glacial supply to Laurentian Channel indicates retreat of ice from the shelf edge and diminishing supply of proglacial sediment from the calving embayment in the mid-Scotian Shelf. With the termination of distal proglacial sediment supply, the sedimentation rate diminished rapidly and hemipelagic sedimentation prevailed through the Holocene.

scholarly journals Blooms of Toxic Cyanobacterium Nodularia spumigena in Norwegian Fjords During Holocene Warm Periods

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 257
Author(s):  
Robert Konkel ◽  
Anna Toruńska-Sitarz ◽  
Marta Cegłowska ◽  
Žilvinas Ežerinskis ◽  
Justina Šapolaitė ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Phytoplankton Community ◽  
Sediment Cores ◽  
Specific Chemical ◽  
Nodularia Spumigena ◽  
History Of ◽  
Recent Sediments ◽  
Species Specific ◽  
Ecosystem Changes ◽  
Deep Sediments

In paleoecological studies, molecular markers are being used increasingly often to reconstruct community structures, environmental conditions and ecosystem changes. In this work, nodularin, anabaenopeptins and selected DNA sequences were applied as Nodularia spumigena markers to reconstruct the history of the cyanobacterium in the Norwegian fjords. For the purpose of this study, three sediment cores collected in Oslofjorden, Trondheimsfjorden and Balsfjorden were analyzed. The lack of nodularin in most recent sediments is consistent with the fact that only one report on the sporadic occurrence and low amounts of the cyanobacterium in Norwegian Fjords in 1976 has been published. However, analyses of species-specific chemical markers in deep sediments showed that thousands of years ago, N. spumigena constituted an important component of the phytoplankton community. The content of the markers in the cores indicated that the biomass of the cyanobacterium increased during the warmer Holocene periods. The analyses of genetic markers were less conclusive; they showed the occurrence of microcystin/nodularin producing cyanobacteria of Nostocales order, but they did not allow for the identification of the organisms at a species level.

Late Paleozoic detrital history of eastern Gondwanaland: petrofacies and detrital geochronology of Permo-Carboniferous intracratonic sequences of the northwest Bengal Basin

2020 ◽  
Vol 90 (4) ◽  
pp. 389-402 ◽  
Author(s):  
Md. Iftekhar Alam ◽  
Ashraf Uddin ◽  
Willis E. Hames
Keyword(s):  
Sediment Cores ◽  
Granulite Facies ◽  
Mineral Chemistry ◽  
Dominant Mode ◽  
Heavy Minerals ◽  
Bengal Basin ◽  
Peninsular India ◽  
History Of ◽  
Age Range ◽  
Sandstone Petrography

ABSTRACT Permo-Carboniferous Gondwanan sequences have been reported from several isolated basins of Peninsular India. These siliciclastic sequences were preserved in several intracratonic basins in northwest Bangladesh. Sandstone petrography, heavy-mineral assemblages, mineral chemistry, and 40Ar/39Ar geochronology of sediment cores were used in this study to decipher the provenance history of Gondwanan sediments at two localities (Khalashpir and Barapukuria). Petrographic studies suggest that these sequences are mostly immature and poorly sorted arkosic sandstones (Khalashpir-Qt60F27L13, Barapukuria-Qt52F31L17), with compositions ranging from quartzarenite to litharenite. Among lithic fragments, sedimentary types are abundant. Heavy minerals are volumetrically rare and of low diversity in sediments of northwest Bangladesh. Garnet geochemistry indicates that metamorphic grades in the source terranes were of the amphibolite to granulite facies. Laser 40Ar/39Ar ages for single crystals of detrital muscovite from the deepest drilled Gondwanan sequences yielded the broadest age range, with a dominant mode at circa 515 Ma and lesser clusters of ages at circa 550, 570, and 600 Ma. The other two shallower samples are dominated by ages with similar single modes at circa 495–500 Ma. The oldest muscovite crystals may have been derived from the adjacent Indian craton and/or the Meghalayan craton. Younger muscovite crystals may have been contributed from the Pinjarra Orogen, formed during episodes of Neoproterozoic to early Paleozoic collision among India, Antarctica, and Australia.

scholarly journals Three novel species of Bacillariophyta (Diatoms) belonging to Aulacoseira and Lindavia from the Pliocene Hadar Formation, Afar Depression of Ethiopia

Phytotaxa ◽  
2016 ◽  
Vol 272 (4) ◽  
pp. 235
Author(s):  
JOSEPH MOHAN ◽  
JEFFERY R. STONE ◽  
CHRISTOPHER J CAMPISANO
Keyword(s):  
Evolutionary History ◽  
Novel Species ◽  
Sediment Cores ◽  
Core Material ◽  
Afar Depression ◽  
Sedimentary Deposits ◽  
Extant Species ◽  
History Of ◽  
Drilling Project ◽  
Hadar Formation

Paleolake Hadar was an expansive lake in the lower Awash Valley of Ethiopia’s Afar Depression that existed periodically through the Late Pliocene. The sedimentary deposits from this ancient lake (Hadar Formation) have broad importance because a significant number of hominin fossils have been recovered from the formation. Samples of the Hadar Formation lacustrine sequence were collected from sediment cores extracted as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP). A paleoecological study of the HSPDP Northern Awash (Hadar Formation) material has unearthed three novel species of Bacillariophyta (diatoms) from diatomites that appear periodically in the cores. The Hadar Formation assemblage represents a newly revealed excerpt from the evolutionary history of freshwater diatoms in East Africa during the Piacenᴢian age (2.59–3.60 Ma). The HSPDP Northern Awash diatom species are compared to previously reported diatoms from Pliocene outcrops, modern and fossil core material from Lake Malawi, and extant species. Here we describe two new species of Aulacoseira and one of Lindavia. Taxonomic treatment of two diatom varieties reported by previous researchers as Melosira are transferred into Aulacoseira herein.

A palynological study of postglacial vegetation changes in the University Research Forest, southwestern British Columbia

1973 ◽  
Vol 51 (11) ◽  
pp. 2085-2103 ◽  
Author(s):  
Rolf W. Mathewes
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Vegetation Change ◽  
Vegetation History ◽  
Sediment Cores ◽  
Silty Clay ◽  
Pollen Diagram ◽  
History Of ◽  
Palynological Study ◽  
The University

The postglacial vegetation history of the University of British Columbia Research Forest was investigated using percentage and absolute pollen analysis, macrofossil analysis, and radiocarbon dating. A marine silty clay deposit records the oldest (12 690 ± 190 years before present (B.P.)) assemblage of terrestrial plant remains so far recovered from the postglacial of south-coastal British Columbia. Lodge-pole pine (Pinus contorta) dominated this early vegetation, although some Abies, Picea, Alnus, and herbs were also present. Sediment cores from two lakes were also studied. The older is Marion Lake, where five pollen assemblage zones are recognized, beginning with a previously undescribed assemblage of Pinus contorta, Salix, and Shepherdia in clay older than 12 350 ± 190 B.P. The pollen diagram from Surprise Lake (11 230 ± 230 B.P.) is divided into three pollen zones which show the same major trends of vegetation change as the Marion Lake diagram.The first report of the postglacial vegetation history of cedar (Thuja and perhaps Chamaecyparis) in southwestern British Columbia is presented from pollen and macrofossil analyses.At about 10 500 B.P. in both lakes, pollen of Douglas fir (Pseudotsuga menziesii) began a rapid increase, probably in response to climatic amelioration. The palynological evidence, supported by well-preserved bryophyte subfossils, suggests that humid coastal conditions have prevailed in the study area since about 10 500 B.P., with virtually no evidence for a classical Hypsithermal interval between 8500 B.P. and 3000 B.P.

scholarly journals Glacial-Marine Sedimentation, Canadian Polar Margin, North of Axel Heiberg Island

2007 ◽  
Vol 45 (2) ◽  
pp. 213-227 ◽  
Author(s):  
Frances J. Hein ◽  
Peta J. Mudie
Keyword(s):  
Sediment Cores ◽  
Open Water ◽  
Silty Clay ◽  
Sedimentation Rates ◽  
The Core ◽  
Marine Sedimentation ◽  
Northwestern Shelf ◽  
History Of ◽  
Axel Heiberg Island ◽  
High Sediment

ABSTRACT Sediment cores, taken at depths of 140 to 300 m across the northwestern shelf of Axel Heiberg Island (82° N), record the deposition of sediments under perennial sea ice. Five sedimentary fades are recognized: (A) soft pebbly-sandy-mud with dropstone structures; (B) bioturbated silty muds; (C) wispy-laminated silty clay/clay; (D) laminated sands/silts and mud; (E) firm pebbly-sandy-mud with chaotic pebble fabrics. Other sediments include terrestrial bedrock of Paleogene Eureka Sound Group, and a younger Tertiary deposit, possibly the Beaufort Formation. Ages range from 1530 ± 60 BP (Fades A) to 9950 ± 80 BP (Fades D). Sedimentation rates vary as follows: - 0.8 cm ka-1, Fades B; 4 cm ka"\ Fades A; 90 cm ka-1, Fades C; 134 cm ka~', Fades D. The sedimentation history, as interpreted from the sedimentology, palynology and foraminiferal results, suggests intervals of more continuous ice cover, with a reduced influx of coarse ice-rafted detritus, alternating with more open water conditions, and high sediment input from meltwater and/or floating icebergs. Only marine sediments overlie Neogene bedrock in the cores. The absence of diamictons at the core sites suggests that grounded ice perhaps never occupied this part of the Axel Heiberg Island shelf. The interpreted history of sedimentation generally corresponds to the land-based record from Ellesmere Island, but differs significantly from marine-based studies in more southern latitudes.

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