scholarly journals Thermoluminescence Dating of Late Pleistocene Sediments, St. Lawrence Lowland, Québec

2007 ◽  
Vol 42 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Michel Lamothe ◽  
David J. Huntley
Keyword(s):  
Late Pleistocene ◽  
Late Glacial ◽  
Future Research ◽  
Eastern Canada ◽  
Tl Dating ◽  
Glacial Sediments ◽  
Thermoluminescence Dating ◽  
Method R

ABSTRACT This paper presents the results of a thermoluminescence (TL) dating program applied to waterlaid sediments of Late Pleistocene age, collected in the central St. Lawrence Lowland, in eastern Canada. The apparent TL ages were obtained using a partial bleach method (R-Gamma) in which the TL from light-sensitive traps is separated from the total TL. Fluvial (modern), marine (late-glacial) lacustrine (interstadial) and glacio-lacustrine (stadial) sediments yielded apparent ages ranging from 4 to 135 ka, and in general, these ages agreed with available stratigraphic evidence. Whilst testing the zeroing assumption, apparent TL ages obtained from modern fluvial and late glacial sediments suggest that laboratory overbleaching or insufficient natural bleaching may result in over-estimation of the apparent TL ages by 4-5 ka. All samples display anomalous fading, a problem that can be overcome by introducing a three month delay between artificial irradiation and glowing. Future research should focus on sediments for which the age as well as the sedimentology are well documented, such as the late glacial Champlain Sea sediments.

scholarly journals Glacial Stratigraphy of the Bulkley River Region: A Depositional Framework for the Late Pleistocene in Central British Columbia*

2006 ◽  
Vol 58 (2-3) ◽  
pp. 217-228 ◽  
Author(s):  
Andrew J. Stumpf ◽  
Bruce E. Broster ◽  
Victor M. Levson
Keyword(s):  
British Columbia ◽  
Late Pleistocene ◽  
Late Glacial ◽  
Ice Flow ◽  
Glacial Sediments ◽  
Fine Grained ◽  
Local Erosion ◽  
River Region ◽  
Flow Directions ◽  
Late Wisconsinan

Abstract A depositional framework for late Pleistocene sediments in central British Columbia was developed from the composite stratigraphy of glacial sediments found in the Bulkley River region. Nonglacial deposits correlated to the Olympia Nonglacial Interval, are overlain in succession by sub-till, ice-advance sediments, Late Wisconsinan (Fraser Glaciation) till, and late-glacial sediments. Due to local erosion and depositional variability, some of the units are not continuous throughout the region and differ locally in their thickness and complexity. At the onset of the Fraser Glaciation, ice advance was marked by rising base levels in rivers, lake ponding, and ice marginal subaqueous deposition. Physiography and glacier dynamics influenced the position of drainage outlets, direction of water flow, and ponding. The region was completely ice covered during this glaciation and ice-flow directions were variable, being dominantly influenced by the migrating position of ice divides. Deglaciation was marked by the widespread deposition of fine-grained sediments in proglacial lakes and glaciofluvial sands and gravels at locations with unrestricted drainage.

Thermoluminescence dating applied to a thin winter varve of the late glacial South Thompson silt, south-central British Columbia

1985 ◽  
Vol 22 (11) ◽  
pp. 1736-1739 ◽  
Author(s):  
G. W. Berger
Keyword(s):  
British Columbia ◽  
Late Glacial ◽  
The Other ◽  
Tl Dating ◽  
South Central ◽  
Thermoluminescence Dating ◽  
Other Hand ◽  
Apparent Age

The partial bleach (R–Γ) procedure of thermoluminescence (TL) dating of unheated sediments has been applied to the 2–4 μm sized feldspar-dominated grains from two components of a 10–11 ka BP glaciolacustrine silt. A previous TL study of the 4–11 μm sized feldspars from a ~12 cm thick summer layer of this varved deposit did not produce the correct age. Here it is shown that the 2–4 μm feldspar grains from a contiguous, 5 mm thick clay-rich winter varve give a satisfactory TL apparent age of 14.2 ± 2.3 ka. On the other hand, and consistent with the previous results, the 2–4 μm feldspar grains from the thicker summer layer yield an incorrect high apparent age of 55 ± 13 ka. These results have implications for general TL dating of waterlaid sediments.

scholarly journals New records and AMS radiocarbon dates on Quaternary Walrus ( Odobenus Rosmarus ) from New Brunswick

2002 ◽  
Vol 51 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Randall F. Miller
Keyword(s):  
New Brunswick ◽  
New Records ◽  
Temporal Distribution ◽  
Late Glacial ◽  
Bay Of Fundy ◽  
Eastern Canada ◽  
Radiocarbon Dates ◽  
Odobenus Rosmarus ◽  
Sand And Gravel ◽  
Past Summer

Abstract Walrus fossils are occasionally recovered during scallop dragging in the Bay of Fundy and from sand and gravel deposits along the coastline of New Brunswick in eastern Canada. Six new fossils and four new AMS radiocarbon dates significantly increase the information concerning late-glacial to postglacial walrus in New Brunswick. Dates range from about 12 800 BP to 2 900 BP, almost half falling between 9 000 and 10 000 BP. Temporal distribution of walrus, compared to estimates of past summer sea surface temperature, suggest that in the Bay of Fundy walrus occurred in waters ranging from 12 to 15° C.

Environmental magnetism study of Lake Cadagno, Switzerland

2021 ◽  
Author(s):  
Artin Ali ◽  
Andrea Biedermann ◽  
Jasmine Berg ◽  
Mark Lever ◽  
Hendrik Vogel
Keyword(s):  
Grain Size ◽  
Sedimentary Environment ◽  
Environmental Magnetism ◽  
Late Glacial ◽  
Magnetic Minerals ◽  
Climate Conditions ◽  
Glacial Sediments ◽  
Depth Profiles ◽  
Magnetic Carriers ◽  
Lake Bottom

<p>Climate affects the mineralogy and grain size of sediments deposited in lakes. These properties are reflected in the sediment magnetic properties and can be characterized using magnetic methods. As part of the Cadagno-Project, which recovered several gravity and piston cores spanning the entire lake history from the deglacial to the present from the deepest part of permanently stratified Lake Cadagno, which is due to its peculiar water column chemistry considered an early Earth ocean analogue, our study aims to define changes in climate conditions during sedimentation. Here, we present a rock magnetic dataset (low-field magnetic susceptibility and its temperature dependence, anhysteretic and isothermal remanent magnetization (ARM, IRM), acquired in various fields, AF demagnetization, and hysteresis loops) that helps characterize the concentration, mineralogy, and grain size of magnetic carriers, and their variability with depth. Susceptibility, ARM, and IRM were measured on core sediments down to a depth of 886 cm below the lake bottom, providing a high-resolution record of the sedimentary environment of Lake Cadagno over the last 11,000 years. In addition to these depth profiles, detailed rock magnetic experiments were conducted at specific depths. The cores consist of pelagic sediments, flood turbidites, and late glacial sediments. In order to determine the characteristics of the background sedimentation, only turbidite-free intervals were included in this study. The depth profiles of susceptibility, ARM and IRM have approximately similar variations with depth. They show distinct peaks at the upper parts of the pelagic sediments (156-158 cm below the lake bottom,   ̴1280-1320 cal. Yr Bp) and of the late glacial sediments (826-844 cm below the lake bottom), which can be interpreted as increased concentration of ferromagnetic minerals or as a change in the magnetic mineralogy, in addition to decreasing trend in the background. Several intervals within the pelagic sediments are dominated by low-coercivity minerals (<10 mT), while higher coercivity grains (10–100 mT) contribute significantly at (150-170, 418-448 and 719-735 cm below the lake bottom). Magnetic grain size was analyzed using a Day plot, and shows that single domain magnetite dominates at (844 cm) below the lake bottom, indicating the presence of magnetotactic bacteria, which are believed to dwell mainly in the oxic–anoxic interface where chemical gradients are high. These results provide important constraints on the environmental conditions and climate change recorded by the magnetic minerals in Lake Cadagno.</p>

Progressive glacial retreat in the Southern Altiplano (Uturuncu volcano, 22°S) between 65 and 14 ka constrained by cosmogenic 3He dating

2014 ◽  
Vol 82 (1) ◽  
pp. 209-221 ◽  
Author(s):  
Pierre-Henri Blard ◽  
Jérôme Lave ◽  
Kenneth A. Farley ◽  
Victor Ramirez ◽  
Nestor Jimenez ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Late Glacial ◽  
Glacial Period ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
Glacial Retreat ◽  
Late Glacial Period ◽  
Cold Episode ◽  
Glacial Landforms ◽  
Exposure Ages

AbstractThis work presents the first reconstruction of late Pleistocene glacier fluctuations on Uturuncu volcano, in the Southern Tropical Andes. Cosmogenic 3He dating of glacial landforms provides constraints on ancient glacier position between 65 and 14 ka. Despite important scatter in the exposure ages on the oldest moraines, probably resulting from pre-exposure, these 3He data constrain the timing of the moraine deposits and subsequent glacier recessions: the Uturuncu glacier may have reached its maximum extent much before the global LGM, maybe as early as 65 ka, with an equilibrium line altitude (ELA) at 5280 m. Then, the glacier remained close to its maximum position, with a main stillstand identified around 40 ka, and another one between 35 and 17 ka, followed by a limited recession at 17 ka. Then, another glacial stillstand is identified upstream during the late glacial period, probably between 16 and 14 ka, with an ELA standing at 5350 m. This stillstand is synchronous with the paleolake Tauca highstand. This result indicates that this regionally wet and cold episode, during the Heinrich 1 event, also impacted the Southern Altiplano. The ELA rose above 5450 m after 14 ka, synchronously with the Bolling–Allerod.

scholarly journals Paleoenvironments along the Eastern Laurentide Ice Sheet Margin and Timing of the Last Ice Maximum and Retreat

2008 ◽  
Vol 41 (2) ◽  
pp. 265-277 ◽  
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel
Keyword(s):  
Late Pleistocene ◽  
North Atlantic ◽  
Environmental Changes ◽  
Atlantic Water ◽  
Polar Front ◽  
Water Masses ◽  
Labrador Sea ◽  
Eastern Canada ◽  
North Atlantic Water ◽  
Late Wisconsinan

ABSTRACT Palynological and isotopic analysis in a few deep-sea cores from the Labrador Sea reveals strong environmental changes related to the Late Pleistocene glacial fluctuations over eastern Canada. On the whole, the Labrador Sea was characterized by strong exchanges between North Atlantic water masses, Arctic outflows, and meltwater discharges from Laurentide, Greenland and lnuitian ice sheets. The penetration of temperate Atlantic waters persisted throughout most of the Late Pleistocene, with a brief interruption during the Late Wisconsinan. During this glacial substage, a slight but continuous meltwater runoff from the Laurentide ice margins grounded on the northern Labrador Shelf is indicated by relatively low 18O values and low-salinity (< 30‰) dinocyst assemblages. The calving of the ice margin, the melwater outflow and the subsequent dilution of surface waters offshore Labrador probably contributed to the dispersal of floating ice and, consequently, to a southward displacement of the polar front restraining the penetration of North Atlantic waters into the Labrador Sea. The advection of southern air masses along the Laurentide ice margins, shown by pollen assemblages, was favourable to abundant precipitation and therefore, high ice accumulation rates, especially over northern Labrador during the Late Wisconsinan. The déglaciation is marked by a brief, but significant, melting event of northern Laurentide ice shortly after 17 ka. The main glacial retreat occurred after ca. 11 ka. It allowed restoration of WSW-ENE atmospheric trajectories, increased phytoplanktonic productivity, and penetration of North Atlantic water masses into the Labrador Sea.

scholarly journals Late-glacial to late-Holocene shifts in global precipitation δ<sup>18</sup>O

2015 ◽  
Vol 11 (10) ◽  
pp. 1375-1393 ◽  
Author(s):  
S. Jasechko ◽  
A. Lechler ◽  
F. S. R. Pausata ◽  
P. J. Fawcett ◽  
T. Gleeson ◽  
...  
Keyword(s):  
General Circulation ◽  
Late Holocene ◽  
Late Glacial ◽  
General Circulation Models ◽  
Future Research ◽  
Quaternary Climate ◽  
Simulated Precipitation ◽  
The Tropics ◽  
Global Precipitation ◽  
Precipitation Δ18o

Abstract. Reconstructions of Quaternary climate are often based on the isotopic content of paleo-precipitation preserved in proxy records. While many paleo-precipitation isotope records are available, few studies have synthesized these dispersed records to explore spatial patterns of late-glacial precipitation δ18O. Here we present a synthesis of 86 globally distributed groundwater (n = 59), cave calcite (n = 15) and ice core (n = 12) isotope records spanning the late-glacial (defined as ~ 50 000 to ~ 20 000 years ago) to the late-Holocene (within the past ~ 5000 years). We show that precipitation δ18O changes from the late-glacial to the late-Holocene range from −7.1 ‰ (δ18Olate-Holocene > δ18Olate-glacial) to +1.7 ‰ (δ18Olate-glacial > δ18Olate-Holocene), with the majority (77 %) of records having lower late-glacial δ18O than late-Holocene δ18O values. High-magnitude, negative precipitation δ18O shifts are common at high latitudes, high altitudes and continental interiors (δ18Olate-Holocene > δ18Olate-glacial by more than 3 ‰). Conversely, low-magnitude, positive precipitation δ18O shifts are concentrated along tropical and subtropical coasts (δ18Olate-glacial > δ18Olate-Holocene by less than 2 ‰). Broad, global patterns of late-glacial to late-Holocene precipitation δ18O shifts suggest that stronger-than-modern isotopic distillation of air masses prevailed during the late-glacial, likely impacted by larger global temperature differences between the tropics and the poles. Further, to test how well general circulation models reproduce global precipitation δ18O shifts, we compiled simulated precipitation δ18O shifts from five isotope-enabled general circulation models simulated under recent and last glacial maximum climate states. Climate simulations generally show better inter-model and model-measurement agreement in temperate regions than in the tropics, highlighting a need for further research to better understand how inter-model spread in convective rainout, seawater δ18O and glacial topography parameterizations impact simulated precipitation δ18O. Future research on paleo-precipitation δ18O records can use the global maps of measured and simulated late-glacial precipitation isotope compositions to target and prioritize field sites.

Glacial history reflected by geochemically constrained stratigraphic sections in the Chaudière River drainage basin of the Canadian Appalachians

2018 ◽  
Vol 91 (1) ◽  
pp. 234-249 ◽  
Author(s):  
William W. Shilts ◽  
Olivier J. Caron
Keyword(s):  
New York ◽  
Drainage Basin ◽  
Early Pleistocene ◽  
Eastern United States ◽  
Eastern Canada ◽  
Glacial Deposits ◽  
Glacial Sediments ◽  
Oxygen Isotope Stage ◽  
River Region ◽  
History Of

AbstractThe Chaudière River region in the Appalachian Mountains of eastern Canada is approximately 700 km north of the southernmost Pleistocene glacial deposits in New York and New Jersey. Detailed compositional analyses of glacial and non-glacial sediments from stratigraphic exposures and more than 40 boreholes drilled to bedrock provide a compositionally constrained record of glacial events, which include deposits of one Marine Oxygen Isotope Stage (MIS) 6 and two post-MIS 5 glaciations. The glacial and associated proglacial deposits rest on compositionally distinctive, preglacial saprolite that is preserved in deeper valleys. These observations constrain interpretations of the glacial/Pleistocene history of the eastern United States and Canada. The fact that there is no unequivocal evidence of pre-MIS 6 till in the Chaudière River region, while there are well-documented pre-MIS 6 glacial deposits south of there and in the American Midwest, also has major climatic implications. The Laurentide Ice Sheet and its ancestors must have been more robust in the west in the early Pleistocene and in the east most recently.

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