Middle Wisconsinan Climate Fluctuations Recorded in Central Alaskan Loess

Begét, James E.

doi:10.7202/032793ar

Cited by 30 publications

(13 citation statements)

References 21 publications

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“…In addition to the Chena Hot Springs Road site, Holocene loess deposition is also recorded at the Delta Junction site, approximately 130 km southeast of Fairbanks . These findings confirm previously published reports of Holocene loess deposition across central Alaska (Péwé, 1975;Hamilton et al, 1983;Begét, 1990) when both loess production and accumulation rates appear to be high . The presence of at least two paleosols at Delta Junction, from a section that dates to ca.…”

Section: Discussionsupporting

confidence: 92%

“…Alaskan loess is of particular interest for paleoclimate studies because it is one of the most extensive and best studied highlatitude loess sequences in the world. Holocene loess records as complete and extensive as those contained in Alaskan loess are rare (Péwé, 1975;Begét, 1990Begét, , 2001Vlag et al, 1999;McDowell and Edwards, 2001;Muhs et al, , 2008Lagroix and Banerjee, 2002). Westgate et al (1990) suggested that the Alaskan loess record may extend as far back as three million years.…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies document the existence of numerous buried soils within loess deposits across central Alaska and the Canadian Yukon (Hamilton et al, 1988;Begét and Hawkins, 1989;Begét, 1990;Begét et al, 1990;Hamilton and Brigham-Grette, 1991;Vlag et al, 1999;McDowell and Edwards, 2001;Muhs et al, , 2008Lagroix and Banerjee, 2002;Sanborn et al, 2006). Their presence indicates periods of relative landscape stability when loess deposition rates were significantly reduced so that pedogenesis could occur Muhs et al, , 2008.…”

Section: Introductionmentioning

confidence: 99%

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Micromorphology of an Early Holocene Loess-Paleosol Sequence, Central Alaska, U.S.A

Josephs

2010

Arctic, Antarctic, and Alpine Research

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This paper describes a micromorphological investigation of an early Holocene loesspaleosol sequence at the Chena Hot Springs Road site, a highway road cut exposure near Fairbanks, Alaska, U.S.A. The procedure identified and described soil microstructure, basic mineral components and their related distributions, organic inclusions, and pedogenic features. Micromorphology confirmed the presence of a number of thin, discontinuous, weakly expressed soils that evince disturbance by diagenetic, graviturbative, and cryoturbative processes. Well-preserved organic remains indicate the presence of a boreal forest that would have acted as a highly effective sediment trap. The frequent observation of detrital iron-oxide grains is consistent with other studies of area loess that reveal high concentrations of magnetite and ilmenite, resulting in significant increases in magnetic susceptibility. Increases in wind strength are likely responsible for the increased clay content in the buried paleosols. Loess deposition, which would inhibit pedogenesis, is probably related to greater wind strength, while pedogenesis, indicative of stability and minimal deposition, suggests periods of reduced wind.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Micromorphology of an Early Holocene Loess-Paleosol Sequence, Central Alaska, U.S.A

Josephs

2010

Arctic, Antarctic, and Alpine Research

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“…Schirrmeister et al, 2002Schirrmeister et al, , 2013Andreev et al, 2002Andreev et al, , 2004Murton et al, 2015), Interior Alaska (e.g. Matthews, 1974;Hamilton et al, 1988;Begét, 1990;McDowell and Edwards, 2001;Schirrmeister et al, 2016), and in the Klondike region in Yukon (e.g. Sanborn et al, 2006;Froese et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Middle to late Wisconsinan climate and ecological changes in northern Alaska: Evidences from the Itkillik River Yedoma

Lapointe

Talbot

Fortier

et al. 2017

Palaeogeography, Palaeoclimatology, Palaeoecology

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Continuous paleoenvironmental records covering the period prior to the Last Glacial Maximum in northeastern Beringia are sparse. This study presents a multi-proxy analysis of a 35-m-high yedoma exposure located on the right bank of the Itkillik River in Alaska. The exposure accumulated over 39 thousand years (kyr) during the Middle Wisconsinan Interstadial and the Late Wisconsinan glacial advance. We identified five stratigraphic units based on pollen, carbon and ice content, and isotopic composition (δ 18 O) of the sediments. Middle Wisconsinan climate in northern Alaska promoted peat accumulation prior to 33.6 cal kyr BP (calibrated kyr before present). Reconstructed July air temperatures were 1-2°C lower than current at 34.8 cal kyr BP, consistent with the timing of the interstadial climatic optimum in interior Alaska and Yukon. Colder (by up to 4°C) and drier conditions characterize the transition from interstadial to glacial conditions between 33.6 and 29.8 cal kyr BP. Late Wisconsinan (29.8-17.9 cal kyr BP) July air temperatures were 2-3°C lower than today, with grassland vegetation dominated by Poaceae, Artemisia and forbs, in contrast to the modern Cyperaceae dominance. Moister and warmer environmental conditions after 17.9 cal kyr BP correspond to the Late Glacial to Early Holocene interval.

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“…We present a continuous ~37,000-year record of paleo-environmental change inferred from physical, geochemical, and environmental magnetic analyses of sediment cores from Burial Lake, Arctic Alaska, with a well-constrained radiocarbon chronology determined from accelerator mass spectrometry (AMS), that provides the oldest continuous lacustrine record from eastern Beringia to date.Previous magnetic studies on Alaskan loess (Begét, 1990;Begét et al, 1990;Vlag et al, 1999;Liu et al, 1999;Lagroix and Banerjee, 2002;Muhs et al, 2003a;Muhs and Budhan, 2006;Evans et al, 2011) provide diagnostic magnetic parameters that allow locally weathered hematite-rich bedrockto be distinguishedfrom ferrimagnetic (magnetite-rich) aeolian dust.Performingthis study within a simple depositional basin with no direct inflow or glacial influenceallows us to reconstruct the paleo-record of aeolian dust and its evolution for NW Alaska.…”

Section: Introductionmentioning

confidence: 99%

A 37,000-year environmental magnetic record of aeolian dust deposition from Burial Lake, Arctic Alaska

Dorfman

Stoner

Finkenbinder

et al. 2015

Quaternary Science Reviews

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Environmental magnetism and radiocarbon dating of Burial Lake sedimentsconstrain the timing and magnitude of regional aeolian deposition for the Noatak region of western Arctic Alaska for the last ~37,000 years. Burial Lake (68.43°N, 159.17°W, 21.5 m water depth) is optimally located to monitor regional dust deposition because it is perched above local drainage and isolated from glacial processes.Cores collected in the summer of 2010 were studied through the application of magnetizations and progressive alternating field(AF) demagnetization of u-channel samples, with additional data provided by computed tomography (CT) derived density,hysteresis measurements, isothermal remanent magnetization (IRM)acquisition experiments,organic carbon content, biogenic silica,physical grain size, radiocarbon datingof terrestrial macrofossils, and point source magnetic susceptibility and X-ray fluorescence(XRF) on split cores.With similar magnetic properties to regional Alaskanloess deposits, low coercivity, highly magnetic material depositedduring the glacial contrasts witha highcoercivity, weakly magneticcomponent found throughout the record, consistent withlocally-derived detritus.The relative proportion of low coercivity to high coercivity magnetic material, defined by the S-Ratios, is used to reconstruct the regional input of dust to the basin over time. A four-fold decrease in the low coercivity component through the deglacial transition is interpreted to reflect diminished dust input to the region.Comparisons with potential sources of dust show that the timing of deposition in Burial Lake is largely consistent with general aridity, lack of vegetative cover, and increased windiness, rather than glacial advances or retreats. The influence from subaerial exposure of continental shelves cannot be ruled out as a significant farfield source of dust to interior Alaska during the Last Glacial Maximum (LGM), but is unlikely to have been the sole source, or to have contributed to increased dust in both the early and late Holocene.

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Middle Wisconsinan Climate Fluctuations Recorded in Central Alaskan Loess

Cited by 30 publications

References 21 publications

Micromorphology of an Early Holocene Loess-Paleosol Sequence, Central Alaska, U.S.A

Micromorphology of an Early Holocene Loess-Paleosol Sequence, Central Alaska, U.S.A

Middle to late Wisconsinan climate and ecological changes in northern Alaska: Evidences from the Itkillik River Yedoma

A 37,000-year environmental magnetic record of aeolian dust deposition from Burial Lake, Arctic Alaska

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