Late Pleistocene and Holocene ice-wedge activity on the Blackstone Plateau, central Yukon, Canada

2018 ◽  
Vol 91 (1) ◽  
pp. 179-193 ◽  
Author(s):  
Mike Grinter ◽  
Denis Lacelle ◽  
Natalia Baranova ◽  
Sarah Murseli ◽  
Ian D. Clark
Keyword(s):  
Isotopic Composition ◽  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Environmental Conditions ◽  
Moisture Source ◽  
Ice Wedge ◽  
Western Arctic ◽  
Plateau Central ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractIce-wedge activity can be used to reconstruct past environmental conditions. We investigated the moisture source and timing of ice-wedge formation on the Blackstone Plateau. A section of permafrost exposed ice wedges that developed at two distinct depths: the first set formed syngenetically and penetrated alluvial silts from the top of permafrost; the second set, truncated by an erosional or thaw contact, was found solely in icy muddy gravels (>3.1 m depth). The δ18O and D-excess records of the ice wedges suggest that they formed from freezing of snow meltwater whose isotopic composition evolved during meltout. The14CDOCresults suggest that climate was favorable to ice-wedge growth between 32,000–30,000 and 14,000–12,500 cal yr BP, but there was likely a hiatus during the last glacial maximum due to climate being too dry. During the early to mid-Holocene, ice wedges were inactive as a result of warmer and wetter climate. Ice wedge re-initiated around 6360 cal yr BP, with a peak in activity between 3980 and 920 cal yr BP, a period characterized by cool and moist climate. Overall, timing of ice-wedge activity was broadly consistent with the climate and vegetation evolution in the western Arctic.

Paleo-climate of the Boise area, Idaho from the last glacial maximum to the present based on groundwater δ2H and δ18O compositions

2009 ◽  
Vol 71 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Melissa E. Schlegel ◽  
Alan L. Mayo ◽  
Steve Nelson ◽  
Dave Tingey ◽  
Rachel Henderson ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Deuterium Excess ◽  
Moisture Source ◽  
Last Glacial ◽  
Stable Isotopic Composition ◽  
Stable Isotopic ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractA 30 ka paleo-climate record of the Boise area, Idaho, USA has been delineated using groundwater stable isotopic compositions. Groundwater ages are modern (cold batholith), 5–15 ka (thermal batholith), 10–20 ka (frontal fault), and 20–30 ka (Snake River plain thermal). The stable isotopic composition of groundwaters have been used as a surrogate for the stable isotopic composition of precipitation. Using δ2H and δ18O compositions, local groundwater lines (LGWL's) were defined for each system. Each LGWL has been evaluated with defined slopes of 6.94 and 8, respectively, and resulting deuterium excess values (d) were found for each groundwater system for each slope. Time dependent changes in moisture source humidity and temperature, and Boise area recharge temperatures, calculated from stable isotopic data and the deuterium excess factors, agree with previous paleo-climate studies. Results indicate that from the last glacial maximum to the present time the humidity over the ocean moisture source increased by 9%, sea surface temperature at the moisture source increased 6–7°C, and local Boise temperature increased by 4–5°C. A greater increase of temperature at the moisture source as compared to the Boise area may impart be due to a shift in the moisture source area.

Comparing a new paleomap of European loess landscapes to an atmospheric dust circulation model

2021 ◽  
Author(s):  
Janina J. (Bösken) Nett ◽  
Frank Lehmkuhl ◽  
Erik J. Schaffernicht ◽  
Stephan Pötter ◽  
Philipp Schulte ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Circulation Model ◽  
Glacial Maximum ◽  
Source Areas ◽  
Last Glacial ◽  
Potential Source ◽  
Aeolian Sediments ◽  
The Last Glacial Maximum ◽  
The Last Glacial

<p>Loess is an important archive of environmental change covering approximately 10% of the Earth’s terrestrial surface. Numerous studies have analyzed loess deposits and in particular loess-paleosol sequences. To analyze these sequences, it is important to know the spatial distribution of aeolian sediments, their location relative to potential source areas, and the geomorphology of the sink area. We investigated these aspects by compiling a new map of aeolian sediments in Europe using highly resolved geodata from 27 countries (Lehmkuhl et al., in press). To determine the most relevant factors for the European loess distribution, we further mapped potential source areas and divided the map into different facies domains. We analyzed the geomorphological and paleoenvironmental effects on the deposition and preservation of Late Pleistocene loess. Finally, the geodata-based results were compared with results obtained from high-resolved regional numerical climate-dust experiments for the Last Glacial Maximum (LGM) in Europe, which were performed with the LGM-adapted Weather Research and Forecasting model coupled with Chemistry (WRF-Chem-LGM; Schaffernicht et al., 2020).  Complementing the mapping-based findings with the WRF-Chem-LGM experiments results in an improved understanding of the Late Pleistocene loess landscape in Europe.</p><p> </p><p>References:</p><p>Lehmkuhl, F., Nett, J.J., Pötter, S., Schulte, P., Sprafke, T., Jary, Z., Antoine, P., Wacha, L., Wolf, D., Zerboni, A., Hošek, J., Marković, S.B., Obreht, I., Sümegi, P., Veres, D., Zeeden, C., Boemke, B., Schaubert, V., Viehweger, J., Hambach, U. (in press). Loess landscapes of Europe – Mapping, geomorphology, and zonal differentiation. Earth-Science Reviews. Doi: https://doi.org/10.1016/j.earscirev.2020.103496</p><p>Schaffernicht, E.J., Ludwig, P., Shao, Y., 2020. Linkage between dust cycle and loess of the last Glacial Maximum in Europe. Atmospheric Chemistry and Physics 20, 4969–4986. Doi:10.5194/acp-20-4969-2020.</p>

Wetter or colder during the Last Glacial Maximum? Revisiting the pluvial lake question in southwestern North America

2004 ◽  
Vol 62 (3) ◽  
pp. 280-288 ◽  
Author(s):  
Kirsten M. Menking ◽  
Roger Y. Anderson ◽  
Nabil G. Shafike ◽  
Kamran H. Syed ◽  
Bruce D. Allen
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Annual Runoff ◽  
Glacial Maximum ◽  
Water Runoff ◽  
Last Glacial ◽  
Pleistocene Climate ◽  
Surface Water Runoff ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Well-preserved shorelines in Estancia basin and a relatively simple hydrologic setting have prompted several inquiries into the basin's hydrologic balance for the purpose of estimating regional precipitation during the late Pleistocene. Estimates have ranged from 86% to 150% of modern, the disparity largely the result of assumptions about past temperatures. In this study, we use an array of models for surface-water runoff, groundwater flow, and lake energy balance to examine previously proposed scenarios for late Pleistocene climate. Constraints imposed by geologic evidence of past lake levels indicate that precipitation for the Last Glacial Maximum (LGM) may have doubled relative to modern values during brief episodes of colder and wetter climate and that annual runoff was as much as 15% of annual precipitation during these episodes.

scholarly journals Exploring the phylogeography and population dynamics of the giant deer ( Megaloceros giganteus ) using Late Quaternary mitogenomes

2021 ◽  
Vol 288 (1950) ◽  
Author(s):  
Alba Rey-Iglesia ◽  
Adrian M. Lister ◽  
Paula F. Campos ◽  
Selina Brace ◽  
Valeria Mattiangeli ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Late Quaternary ◽  
Glacial Maximum ◽  
Climatic Fluctuations ◽  
The Holocene ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Late Quaternary climatic fluctuations in the Northern Hemisphere had drastic effects on large mammal species, leading to the extinction of a substantial number of them. The giant deer ( Megaloceros giganteus ) was one of the species that became extinct in the Holocene, around 7660 calendar years before present. In the Late Pleistocene, the species ranged from western Europe to central Asia. However, during the Holocene, its range contracted to eastern Europe and western Siberia, where the last populations of the species occurred. Here, we generated 35 Late Pleistocene and Holocene giant deer mitogenomes to explore the genetics of the demise of this iconic species. Bayesian phylogenetic analyses of the mitogenomes suggested five main clades for the species: three pre-Last Glacial Maximum clades that did not appear in the post-Last Glacial Maximum genetic pool, and two clades that showed continuity into the Holocene. Our study also identified a decrease in genetic diversity starting in Marine Isotope Stage 3 and accelerating during the Last Glacial Maximum. This reduction in genetic diversity during the Last Glacial Maximum, coupled with a major contraction of fossil occurrences, suggests that climate was a major driver in the dynamics of the giant deer.

Coastal occupation and foraging during the last glacial maximum and early Holocene at Waterfall Bluff, eastern Pondoland, South Africa

2020 ◽  
Vol 97 ◽  
pp. 1-41 ◽  
Author(s):  
Erich C. Fisher ◽  
Hayley C. Cawthra ◽  
Irene Esteban ◽  
Antonieta Jerardino ◽  
Frank H. Neumann ◽  
...  
Keyword(s):  
South Africa ◽  
Continental Shelf ◽  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Marine Fish ◽  
Hunter Gatherers ◽  
The Holocene ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractWaterfall Bluff is a rock shelter in eastern Pondoland, South Africa, adjacent to a narrow continental shelf that limited coastline movements across glacial/interglacial cycles. The archaeological deposits are characterized by well-preserved stratigraphy, faunal, and botanical remains alongside abundant stone artifacts and other materials. A comprehensive dating protocol consisting of 5 optically stimulated luminescence ages and 51 accelerator mass spectrometry 14C ages shows that the record of hunter-gatherer occupations at Waterfall Bluff persisted from the late Pleistocene to the Holocene, spanning the last glacial maximum and the transition from the Pleistocene to the Holocene. Here, we provide detailed descriptions about the sedimentary sequence, chronology, and characteristics of the archaeological deposits at Waterfall Bluff. Remains of marine mollusks and marine fish also show, for the first time, that coastal foraging was a component of some hunter-gatherer groups’ subsistence practices during glacial phases in the late Pleistocene. The presence of marine fish and shellfish further demonstrates that hunter-gatherers selectively targeted coastal resources from intertidal and estuarine habitats. Our results therefore underscore the idea that Pondoland's coastline remained a stable and predictable point on the landscape over the last glacial/interglacial transition being well positioned for hunter-gatherers to access resources from the nearby coastline, narrow continental shelf, and inland areas.

scholarly journals Could brown bears ( Ursus arctos ) have survived in Ireland during the Last Glacial Maximum?

2013 ◽  
Vol 9 (4) ◽  
pp. 20130281 ◽  
Author(s):  
Saoirse A. Leonard ◽  
Claire L. Risley ◽  
Samuel T. Turvey
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Ice Sheet ◽  
Brown Bear ◽  
Glacial Maximum ◽  
Source Population ◽  
Brown Bears ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Brown bears are recorded from Ireland during both the Late Pleistocene and early–mid Holocene. Although most of the Irish landmass was covered by an ice sheet during the Last Glacial Maximum (LGM), Irish brown bears are known to have hybridized with polar bears during the Late Pleistocene, and it is suggested that the Irish brown bear population did not become extinct but instead persisted in situ through the LGM in a southwestern ice-free refugium. We use historical population modelling to demonstrate that brown bears are highly unlikely to have survived through the LGM in Ireland under any combination of life-history parameters shown by living bear populations, but instead would have rapidly become extinct following advance of the British–Irish ice sheet, and probably recolonized Ireland during the end-Pleistocene Woodgrange Interstadial from a closely related nearby source population. The time available for brown bear–polar bear hybridization was therefore restricted to narrow periods at the beginning or end of the LGM. Brown bears would have been extremely vulnerable to extinction in Quaternary habitat refugia and required areas substantially larger than southwestern Ireland to survive adverse glacial conditions.

Simulated regional dust cycle in the Carpathian Basin and the Adriatic Sea region during the Last Glacial Maximum

2021 ◽  
Author(s):  
Patrick Ludwig ◽  
Milivoj B. Gavrilov ◽  
Slobodan B. Markovic ◽  
Gabor Ujvari ◽  
Frank Lehmkuhl
Keyword(s):  
Last Glacial Maximum ◽  
Environmental Conditions ◽  
Carpathian Basin ◽  
Late Winter ◽  
Dust Emissions ◽  
Wind Speeds ◽  
The Last Glacial Maximum ◽  
Adriatic Region ◽  
High Dust ◽  
The Last Glacial

<p>Different climate and environmental conditions dominated in the Carpathian Basin and the adjacent northern Italy/Adriatic region during the Last Glacial Maximum (LGM), as compared to today. For instance, high dust accumulation rates recorded in loess deposits point to an active dust cycle during the LGM. We investigated the climate conditions and regional dust cycle based on high-resolution (grid spacing of ~8.5 km) regional climate simulations for LGM conditions. The model output is in good agreement with proxy data, reproducing cold and dry conditions for the LGM. Highest dust emissions are simulated to the east of the Alpine ice sheet and in the Kvarner Bay region. While simulated dust deposition plumes in the northern Carpathian Basin indicate prevailing northerly (NW, N and NE) winds during dust events, strong Bora winds flowing down the slopes of the Dinaric Alps appear to play a major role in the local to regional dust cycle in the northern Adriatic region. From a seasonal perspective, the simulated dust cycle is most active during late winter and spring. A detailed analysis of climate and environmental conditions at key areas reveals that high wind speeds and low precipitation rates during late winter and spring correlate well with high dust emissions. In contrast, lower wind speeds, increasing precipitation, and the greening of vegetation prevent high dust emissions during summer and autumn. The occurrence of cyclonic circulation patterns in the Adriatic shelf region reveals that individual cyclones played an important role in transporting dust particles from the alluvial Po plain towards the eastern Adriatic loess deposition sites.</p>

scholarly journals Climate Conditions on the Tibetan Plateau During the Last Glacial Maximum and Implications for the Survival of Paleolithic Foragers

2020 ◽  
Vol 8 ◽  
Author(s):  
Xiangjun Liu ◽  
Lu Cong ◽  
Xiangzhong Li ◽  
David Madsen ◽  
Yixuan Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Last Glacial Maximum ◽  
Environmental Conditions ◽  
Climate Model ◽  
Model Simulation ◽  
The Tibetan Plateau ◽  
Simulation Results ◽  
The Last Glacial Maximum ◽  
Age Estimates ◽  
The Last Glacial

Environmental conditions on the Tibetan Plateau (TP) during the last glacial maximum (LGM) are poorly known. Existing studies of environmental proxies and climate model simulations are contradictory, with interpretations varying between cold-dry and cold-wet environmental conditions which differentially influenced lake volumes, loess deposition and vegetation communities across the TP. Genetic and archaeological studies suggest anatomically modern paleolithic foragers initially occupied the TP between 60 and 30 ka, and may have seasonally occupied the TP during the LGM. Hence, a better understanding for LGM environmental conditions is needed in order to estimate whether paleolithic foragers could have survived on the TP during the extreme LGM cold stage. Here we report the investigation of lacustrine sediments and beach deposits within two paleoshorelines around Dagze Co on the southern TP, ∼22 and ∼42 m higher than the present lake level. Optical age estimates suggest the sediments were deposited during the LGM and mid-Holocene, respectively. TraCE-21 climate model simulation results suggest that net annual LGM precipitation in the Dagze Co basin was lower than the mid-Holocene, but about the same as that of the past 1,000 years. Combining the optical age estimates with TraCE-21 and CAM4 climate model simulation results, we deduce that increased summer precipitation and glacier meltwater supply, combined with decreased lake surface evaporation, produced LGM lake levels ∼22 m higher than present. We also synthesized paleoenvironmental records reported across the TP spanning the LGM. This synthesis suggests that the LGM climate in the northern TP was cold and dry, but that some of the southern TP was cold and wet. These relatively wetter LGM conditions in the southern TP may have favored the growth of cold-resistant plants which, in turn, may have supported larger herbivore populations, and provided food for paleolithic foragers. We conclude that seasonal or short-term human occupation of the TP during the LGM was thus more likely in the southern TP than in the north.

Late Pleistocene colonization of South Georgia by yellow-billed pintails pre-dates the Last Glacial Maximum

2013 ◽  
Vol 40 (12) ◽  
pp. 2348-2360 ◽  
Author(s):  
Kevin G. McCracken ◽  
Robert E. Wilson ◽  
Jeffrey L. Peters ◽  
Kevin Winker ◽  
Anthony R. Martin
Keyword(s):  
Last Glacial Maximum ◽  
Late Pleistocene ◽  
Glacial Maximum ◽  
South Georgia ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial
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