Late Quaternary paleoenvironments and growth of intrusive ice in eastern Beringia (Eagle River valley, northern Yukon, Canada)

2010 ◽  
Vol 47 (7) ◽  
pp. 941-955 ◽  
Author(s):  
Bernard Lauriol ◽  
Denis Lacelle ◽  
Mélanie St-Jean ◽  
Ian D. Clark ◽  
Grant D. Zazula
Keyword(s):  
Late Quaternary ◽  
Maximum Level ◽  
River Valley ◽  
Bison Bison ◽  
Glacial Lake ◽  
Silty Clay ◽  
Uneven Surface ◽  
Ground Ice ◽  
Fluvial Terrace ◽  
Cut Marks

In this study, the sediments exposed in a fluvial terrace and in the headwall of a thaw slump in the Eagle River valley, northern Yukon, provide new data about the timing of flooding of glacial Lake Old Crow, the formation of massive ground ice bodies, and the vegetation and the fauna in eastern Beringia during the late Quaternary. The stratigraphy and radiocarbon ages establish the following chronology of events: (1) a gravel fluvial terrace was deposited by an overflow from glacial Lake Hughes into glacial Lake Old Crow; (2) a carbonate silty clay was deposited during the maximum level of glacial Lake Old Crow at 15 120 14C year BP; (3) permafrost and large intrusive ice bodies aggraded through the glaciolacustrine and underlying sediments following the drainage of glacial Lake Old Crow from the site; (4) at 11 290 14C year BP, a shrub–sedge tundra colonized an uneven surface deformed by the bodies of ground ice; (5) a thaw lake drained at 6730 14C year BP after flooding the site; (6) during the early Holocene and from the previous major event onwards, material from the slope nearby the site buried the previous organic and inorganic sediment and the ice bodies; and (7) a bison (Bison) vertebra with conspicuous cut marks was dated to 12 210 ± 70 14C year BP. The age from the bison bone is amongst the most recent of the late Pleistocene bison specimens yet found in eastern Beringia.

The late Wisconsinan olistostrome of the lower Coppermine River valley, Northwest Territories

1986 ◽  
Vol 23 (11) ◽  
pp. 1700-1708 ◽  
Author(s):  
Denis A. St-Onge ◽  
Jean Lajoie
Keyword(s):  
Debris Flows ◽  
Late Quaternary ◽  
Fine Sand ◽  
Coarse Sand ◽  
Coarse Fraction ◽  
River Valley ◽  
Glacial Lake ◽  
The North ◽  
Geologic Record ◽  
Coppermine River

The late Quaternary olistostrome exposed in the lower Coppermine River valley fills a paleovalley that ranges in apparent width from 150 to 400 m and was cut into Precambrian bedrock before the last glaciation. The olistostrome is here named the Sleigh Creek Formation. The coarse fraction of the formation is matrix supported; beds are massive or reversely graded and have sharp, nonerosive contacts. These characteristics suggest deposition of the coarse fraction by debris flows. The olistostrome sequence is bracketed by, and wedged into, a marine rhythmite sequence, which indicates that deposition occurred in a marine environment.About 10 500 years BP glacier ice in the Coronation Gulf lowland dammed the valley to the south, which was occupied by glacial Lake Coppermine. Sediments accumulated in this lake in a 30 m thick, coarsening upward sequence ranging from glaciolacustrine rhythmites of silt and fine sand at the base to coarse sand alluvium, and deltaic gravels at the top. As the Coronation Gulf lowlands became ice free, the Coppermine River reoccupied its former drainage course to the north. The steep south to north gradient and rapid downcutting by the river through the glacial lake sediments produced unstable slope conditions. The resulting debris flows filled a bedrock valley network below the postglacial sea level, forming the diamicton sequence.The interpretation of the Sleigh Creek Formation raises questions concerning silimar diamicton deposits usually defined as "flowtills." More generally, the results of this study indicate that care must be used when attempting paleogeographic reconstructions of "glaciogenic" deposits in marine sequences in any part of the geologic record.

Forage Selectivity of Semi-Free-Roaming Bison (Bison bison) in Sod-Forming Cereal Steppes in the Western Manych River Valley

2020 ◽  
Vol 10 (4) ◽  
pp. 305-311
Author(s):  
V. V. Dzhapova ◽  
O. G. Bembeeva ◽  
E. Ch. Ayusheva ◽  
V. D. Kazmin ◽  
R. R. Dzhapova ◽  
...  
Keyword(s):  
River Valley ◽  
Bison Bison

scholarly journals Time-integrated 3D approach of late Quaternary sediment-depocenter migration in the Tagus depositional system: From river valley to abyssal plain

2016 ◽  
Vol 153 ◽  
pp. 192-211 ◽  
Author(s):  
Geert-Jan Vis ◽  
Cornelis Kasse ◽  
Dick Kroon ◽  
Jef Vandenberghe ◽  
Simon Jung ◽  
...  
Keyword(s):  
Late Quaternary ◽  
River Valley ◽  
Abyssal Plain ◽  
Quaternary Sediment ◽  
Depositional System

Late Quaternary fluvial terrace evolution in the main southern Amazonian tributary

CATENA ◽  
2014 ◽  
Vol 116 ◽  
pp. 19-37 ◽  
Author(s):  
Dilce F. Rossetti ◽  
Marcelo C.L. Cohen ◽  
Thiago C. Bertani ◽  
Ericson H. Hayakawa ◽  
Jackson D.S. Paz ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Fluvial Terrace

scholarly journals Vegetation and climate from Late Quaternary Thimi Formation (Phaidhoka Section), Bhaktapur, Nepal

2015 ◽  
Vol 50 (1) ◽  
pp. 1-12
Author(s):  
Deepak Banjade ◽  
Kabir Sharma ◽  
Khum N. Paudayal
Keyword(s):  
Late Quaternary ◽  
Middle Part ◽  
Temperate Climate ◽  
Silty Clay ◽  
Pollen Diagram ◽  
Formation Zone ◽  
Palynological Study ◽  
Deltaic Deposit ◽  
Warm Temperate ◽  
Vegetation And Climate

The Thimi Formation is fluvio-deltaic deposit that constitutes the uppermost part of the sedimentary sequence in the Kathmandu Basin, and is featured by carbonaceous and diatomaceous clay, silty clay, silt, fine to medium grained sand beds, and thin to medium lignite beds. The Phaidhoka Section is located on the way to Nala from Chyamasingh, and is one of the major exposures of the Thimi Formation. Forty four samples were collected from 25 m thick surface exposure for palynological study. The study revealed the dominance of gymnosperm over the angiosperm and herbaceous members. The pollen diagram suggested Pinus, Picea and Quercus as the most dominant trees whereas Poaceae is other dominant among the grasses. Three major pollen assemblage zones were marked in the Thimi Formation. Zone P-I indicated warm temperate climate, whereas zone P-II and P-III indicated cold temperate climate. Molluscan operculum in the upper part indicated shallow water condition. The Bovid molars, limb and pelvic bones from the middle part of the section confirm the early findings of molar bones in this area.

scholarly journals New ground ice maps for Canada using a paleogeographic modelling approach

2019 ◽  
Vol 13 (3) ◽  
pp. 753-773 ◽  
Author(s):  
H. Brendan O'Neill ◽  
Stephen A. Wolfe ◽  
Caroline Duchesne
Keyword(s):  
Glacial Lake ◽  
Significant Advance ◽  
Small Scale ◽  
Permafrost Degradation ◽  
Field Observations ◽  
Tree Line ◽  
Ground Ice ◽  
Near Surface ◽  
Western Arctic ◽  
Modelling Approach

Abstract. Ground ice melt caused by climate-induced permafrost degradation may trigger significant ecological change, damage infrastructure, and alter biogeochemical cycles. The fundamental ground ice mapping for Canada is now >20 years old and does not include significant new insights gained from recent field- and remote-sensing-based studies. New modelling incorporating paleogeography is presented in this paper to depict the distribution of three ground ice types (relict ice, segregated ice, and wedge ice) in northern Canada. The modelling uses an expert-system approach in a geographic information system (GIS), founded in conceptual principles gained from empirically based research, to predict ground ice abundance in near-surface permafrost. Datasets of surficial geology, deglaciation, paleovegetation, glacial lake and marine limits, and modern permafrost distribution allow representations in the models of paleoclimatic shifts, tree line migration, marine and glacial lake inundation, and terrestrial emergence, and their effect on ground ice abundance. The model outputs are generally consistent with field observations, indicating abundant relict ice in the western Arctic, where it has remained preserved since deglaciation in thick glacigenic sediments in continuous permafrost. Segregated ice is widely distributed in fine-grained deposits, occurring in the highest abundance in glacial lake and marine sediments. The modelled abundance of wedge ice largely reflects the exposure time of terrain to low air temperatures in tundra environments following deglaciation or marine/glacial lake inundation and is thus highest in the western Arctic. Holocene environmental changes result in reduced ice abundance where the tree line advanced during warmer periods. Published observations of thaw slumps and massive ice exposures, segregated ice and associated landforms, and ice wedges allow a favourable preliminary assessment of the models, and the results are generally comparable with the previous ground ice mapping for Canada. However, the model outputs are more spatially explicit and better reflect observed ground ice conditions in many regions. Synthetic modelling products that incorporated the previous ground ice information may therefore include inaccuracies. The presented modelling approach is a significant advance in permafrost mapping, but additional field observations and volumetric ice estimates from more areas in Canada are required to improve calibration and validation of small-scale ground ice modelling. The ground ice maps from this paper are available in the supplement in GeoTIFF format.

Status of Glacial Lake Columbia during the Last Floods from Glacial Lake Missoula

1987 ◽  
Vol 27 (2) ◽  
pp. 182-201 ◽  
Author(s):  
Brian F. Atwater
Keyword(s):  
Columbia River ◽  
River Valley ◽  
Glacial Lake ◽  
Grand Coulee

AbstractThe last floods from glacial Lake Missoula, Montana, probably ran into glacial Lake Columbia, in northeastern Washington. In or near Lake Columbia's Sanpoil arm, Lake Missoula floods dating from late in the Fraser glaciation produced normally graded silt beds that become thinner upsection and which alternate with intervals of progressively fewer varves. The highest three interflood intervals each contain only one or two varves, and about 200–400 successive varves conformably overlie the highest flood bed. This sequence suggests that jökulhlaup frequency progressively increased until Lake Missoula ended, and that Lake Columbia outlasted Lake Missoula. The upper Grand Coulee, Lake Columbia's late Fraser-age outlet, contains a section of 13 graded beds, most of them sandy and separated by varves, that may correlate with the highest Missoula-flood beds of the Sanpoil River valley. The upper Grand Coulee also contains probable correlatives of many of the approximately 200–400 succeeding varves, as do nearby parts of the Columbia River valley. This collective evidence casts doubt on a prevailing hypothesis according to which one or more late Fraser-age floods from Lake Missoula descended the Columbia River valley with little or no interference from Lake Columbia's Okanogan-lobe dam.

scholarly journals Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

2005 ◽  
Vol 57 (1) ◽  
pp. 65-83 ◽  
Author(s):  
Patrick Lajeunesse ◽  
Michel Allard
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Phase 1 ◽  
Second Phase ◽  
Hudson Bay ◽  
Silty Clay ◽  
Paleoenvironmental Reconstruction ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Fluvial Terraces

Abstract This study presents a paleoenvironmental reconstruction of deglaciation dynamics and chronology, glaciomarine and postglacial sedimentation, as well as glacioisostatic recovery in the Rivière Nastapoka area, eastern Hudson Bay. Results indicate that the retreat of Québec-Labrador ice was mainly controlled by topography and was marked by four phases. Radiocarbon dates indicate that deglaciation began about 8.3 ka cal. BP and was characterized by a stillstand of the ice margin in the Nastapoka Hills that lead to the deposition of a drift belt in a high relative sea-level (Phase 1). After this stabilisation, the ice margin retreated rapidly eastward in a region of low relief and deposited a drape of silty clay in a falling relative sea-level (Phase 2). A second phase of stabilization of the ice margin lasted until at least 7.2 ka cal.BP on the higher shield peneplaine east of the limit of the Tyrrell Sea (Phase 3). This lead to the deposition of a belt of glaciofluvial deltas in a lower relative sea-level. Following this stillstand, the eastward retreat and subsequent ablation of the ice in central Québec-Labrador generated meltwater that transported large volumes of glacial sediments by fluvial processes and downcutting of fluvial terraces in previously deposited glaciofluvial and marine sediments (Phase 4). Glacioisostatic rebound reached 0.07 m/yr during the early phase of deglaciation and decreased to 0.04 m/yr between 6 and 5 ka cal. BP and 0.016 m/yr in the last 1000 years.

scholarly journals A Gas-Emission Crater in the Erkuta River Valley, Yamal Peninsula: Characteristics and Potential Formation Model

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 170 ◽  
Author(s):  
Evgeny Chuvilin ◽  
Julia Stanilovskaya ◽  
Aleksey Titovsky ◽  
Anton Sinitsky ◽  
Natalia Sokolova ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
River Valley ◽  
Oxbow Lake ◽  
Yamal Peninsula ◽  
Permafrost Soil ◽  
Formation Model ◽  
Gas Emission ◽  
Ground Ice ◽  
Lake Formation ◽  
Potential Formation

Methane is a powerful greenhouse gas, and the abrupt degassing events that recently have formed large craters on the Russian Arctic Yamal and Gydan Peninsulas have caused major concern. Here we present field data on cover sediments and evolution of a gas-emission crater discovered in the Erkuta–Yakha River valley in the southern Yamal Peninsula in June 2017. The crater is located south of other similar craters discovered over the past decade in northern West Siberia. Data were collected during a field trip to the Erkuta crater in December 2017 which included field observations and sampling of permafrost soil and ground ice from the rim of the crater. All soil and ice samples were measured for contents of methane and its homologs (ethane and propane) and carbon dioxide. The contents of carbon dioxide in some samples are notably higher than methane. The strongly negative δ13С of methane from ground ice samples (−72‰) is typical of biogenic hydrocarbons. The ratio of methane to the total amount of its homologs indicate a component of gases that have migrated from a deeper, thermogenic source. Based on obtained results, a potential formation model for Erkuta gas-emission crater is proposed, which considers the combined effect of deep-seated (deep gas migration) and shallow (oxbow lake evolution and closed talik freezing) causes. This model includes several stages from geological prerequisites to the lake formation.

Sign in / Sign up

Export Citation Format

Share Document