Anomalous-fading rates were measured in K-feldspars separated from 49 sediment samples, mainly from North America. The intensity of the optically stimulated luminescence was found to decrease linea...

Ubiquity of anomalous fading in K-feldspars and the measurement and correction for it in optical dating

Publisher Summary This chapter reviews that the Late Wisconsinan North American ice sheet complex consisted of three major ice sheets: (1) the Laurentide Ice Sheet, which was centred on the Canadian Shield, but also expanded across the Interior Plains to the west and south, (2) the Cordilleran Ice Sheet, which inundated the western mountain belt between the northernmost co-terminus United States and Beringia, and (3) the Innuitian Ice Sheet, which covered most of the Canadian Arctic Archipelago north of about 7°N latitude. The ice cover over Newfoundland and the Maritime Provinces of Canada is usually referred to as the Appalachian Ice Complex, because ice flowed out from local centres rather than from the Canadian Shield. All of the peripheral ice sheets were confluent at the Last Glacial Maximum (LGM) with the Laurentide Ice Sheet, and the Greenland Ice Sheet was confluent with the Innuitian Ice Sheet. The nucleus of this complex, the Laurentide, comprised three major sectors, the Labrador Sector, the Keewatin Sector, and the Baffin Sector, named for areas of inception mid probable areas of outflow at LGM and located respectively east, west and north of Hudson Bay. The chapter presents revised maps of North American deglaciation at 500-year and finer resolution. These maps represent an updating of a series prepared nearly two decades ago for the INQUA 1987 Congress.

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An outline of North American deglaciation with emphasis on central and northern Canada

Morphodynamics of Holocene salt marshes: a review sketch from the Atlantic and Southern North Sea coasts of Europe

Climate fluctuations during the past millennium are relatively well documented1 On a longer timescale, there is growing evidence of millennial-scale variability of Holocene climate, at periodicities of ∼2,500 and 950 years (possibly caused by changes in solar flux)2,3 and ∼1,500 years (maybe related to an internal oscillation of the climate system)4,5,6 But the involvement of deep water masses in these Holocene climate changes has yet to be established Here we use sediment grain-size data from the Iceland basin to reconstruct past changes in the speed of deep-water flow The study site is under the influence of Iceland–Scotland Overflow Water (ISOW), the flow of which is an important component of the ‘thermohaline’ circulation that modulates European climate Flow changes coincide with some known climate events (the Little Ice Age and the Mediaeval Warm Period), and extend over the entire Holocene epoch with aquasi-periodicity of ∼1,500 years The grain-size data indicate afaster ISOW flow when the climate of northern Europe is warmer However, a second mode of operation is observed in the early Holocene, when warm climate intervals are associated with slower ISOW flow At that time the melting remnant of land-based, glacial-age ice may have provided a sufficient source of fresh water to the ocean to reduce ISOW flow south of Iceland

Holocene periodicity in North Atlantic climate and deep-ocean flow south of Iceland

Palaeo-moisture evolution in monsoonal Central Asia during the last 50,000 years

Fourier and nonlinear regression analysis of a 4000+ yr paleoclimate proxy record in western Canada shows strong periodicities of ∼1500 yr and several weaker century- to millenial-scale periodicities. In conjunction with the 23 708 yr Milankovitch periodicity, these produce a model of climate fluctuation through the postglacial consistent with recognized paleoclimatic fluctuations of the past 15 000 yr in the northern mid-latitudes. These results suggest that postglacial climatic anomalies such as the Little Ice Age and the Younger Dryas were at least in part periodic phenomena rather than the result of unique, aperiodic events. Projecting these periodicities into the future suggests that even in the absence of anthropogenic climate forcing, a natural warming trend will continue until ca. a.d. 2400.

https://cfs.nrcan.gc.ca/bookstore_pdfs/18741.pdf

Late Holocene ,-..; 1500 yr climatic periodicities and their implications

A suite of sediment core samples was recovered from two lakes, Crowfoot and Bow lakes, that are adjacent to the Crowfoot moraine type locality, to identify and radiocarbon date sediments related to the Crowfoot advance. The Crowfoot moraine system, widely recognized throughout northwestern North America, represents a glacial advance that is post-Wisconsin and pre-Mazama tephra in age. An interval of inorganic sediments bracketed by accelerator mass spectrometry radiocarbon ages of ca. 11,330 and 10,100 [sup 14]C yr B.P. is associated with the Crowfoot moraine. The Crowfoot advance is therefore approximately synchronous with the European Younger Dryas cold event (ca. 11,000-10,000 [sup 14]C yr B.P.). Furthermore, the termination of the Crowfoot advance also appears to have been abrupt. These findings illustrate that the climatic change responsible for the European Younger Dryas event extended beyond the northern Atlantic basin and western Europe. Equilibrium-line altitude (ELA) depressions associated with the Crowfoot advance are similar to those determined for the Little Ice Age advance, whereas Younger Dryas ELA depressions in Europe significantly exceed Little Ice Age ELA depressions. 26 refs., 3 figs., 1 tab.

Age of the Crowfoot advance in the Canadian Rocky Mountains: A glacial event coeval with the Younger Dryas oscillation

Re-arrangement of atmospheric circulation at about 2.6 Ma over northern China: evidence from grain size records of loess-palaeosol and red clay sequences

SUMMARY A Late Quaternary loess/palaeosol sequence at Kurtak in the Yenisey River valley, southern Siberia, has been studied magnetically. The 34 m section (340 samples) exhibits variations in magnetic susceptibility which can be correlated with oxygen isotope stages 1‐7. A detailed sampling of stage 5 (a further 209 samples) permits the identification of substages 5a‐e. The susceptibility variations themselves are in the opposite sense to that found in the classic sections of the Chinese Loess Plateau, but are in agreement with the ‘wind-intensity’ model which has been put forward to explain similar findings in loess sequences in Alaska. Published results for the susceptibility of magnetite imply volume fractions of #0.2 per cent in glacial stages 2 and 4, dropping to #0.05 per cent in stages 1, 3 and 5. These fluctuations match the aeolian flux variations observed in core V21‐146 from the north Pacific. Even though the warmer intervals are characterized by lower susceptibilities, the observed frequency dependence of susceptibility indicates that new magnetic material is produced as a result of pedogenesis during interglacial and interstadial times.

/pdf/a-magnetic-investigation-of-a-late-quaternary-loess-2seijjleoy.pdf

A magnetic investigation of a Late Quaternary loess/palaeosol record in Siberia

Clay minerals from the loess-paleosol section at Baoji in north-central China were studied by X-ray Diffraction. Major components, calculated by comparing major peak heights, were estimated as follows: illite (55–75%), kaolinite (10–25%), mixed layer chlorite-vermiculite (10–20%), chlorite (

N.W. Rutter

Papers

Late Holocene ,-..; 1500 yr climatic periodicities and their implications

Age of the Crowfoot advance in the Canadian Rocky Mountains: A glacial event coeval with the Younger Dryas oscillation

Re-arrangement of atmospheric circulation at about 2.6 Ma over northern China: evidence from grain size records of loess-palaeosol and red clay sequences

A magnetic investigation of a Late Quaternary loess/palaeosol record in Siberia

Clay minerals and their paleoenvironmental interpretation in the Baoji loess section, Southern Loess Plateau, China