Isotopic composition of a large photosymbiotic foraminifer: Evidence for hypersaline environments across the Great Australian Bight during the late Pleistocene

2009 ◽  
Vol 213 (3-4) ◽  
pp. 113-120 ◽  
Author(s):  
John M. Rivers ◽  
T. Kurt Kyser ◽  
Noel P. James
Keyword(s):  
Isotopic Composition ◽  
Late Pleistocene ◽  
Hypersaline Environments ◽  
Great Australian Bight

scholarly journals On the reliability of the Vasilchuk’s paleotemperature-isotopiv equations and the establishment of isotopic paleogeocryology

2021 ◽  
pp. 1-26
Author(s):  
Alla Constantinovna Vasil'chuk ◽  
Nadine Arkad'evna Budantseva ◽  
Galina Vyacheslavovna Surkova ◽  
Julia Nikolaevna Chizhova
Keyword(s):  
Isotopic Composition ◽  
Late Pleistocene ◽  
Winter Season ◽  
Winter Period ◽  
Regression Equations ◽  
Temperature Characteristics ◽  
The Holocene ◽  
Temperature Range ◽  
Direct Dependence

This article is dedicates to the assessment of the contribution of Professor Vasilchuk to the development of isotopic geocryology, as well as testing the reliability of paleogeocryological reconstructions based on the study of isotopic composition of polygonal ice wedges. His discovery of direct dependence of isotopic composition of the sprouts of modern ice wedges on the temperature characteristics of the winter season of 1989 marked the beginning of a promising research of the Holocene and Late Pleistocene syngenetic ice wedges as a reliable paleoclimatic archive. He was first to obtain the characteristics of the winter period for the late Pleistocene and Holocene, as well as create the maps for distributing paleotemperatures for the key periods of Late Pleistocene. The data on the isotopic composition of ice wedges acquired by other scholars later fit into the distribution of paleotemperature within the cryolithozone reconstructed by Professor Vasilchuk. For establishing the degree of reliability of paleotemperature reconstructions, the authors tested the ratio proposed by Y. K. Vasilchuk and regression equations from the works of Konyakhin, Mayer, and Oblogov. The acquired results demonstrate that the values of winter-average and January-average temperatures in reconstruction by Vasilchuk’s ratio always fall within the reliability interval in the entire modern temperature range. Testing the current temperature using regression equations often determine a considerable deviation (often within 3-4°C) from the actual values of winter-average and January-average temperatures.

The oxygen isotope stratigraphic record of the Late Pleistocene

1977 ◽  
Vol 280 (972) ◽  
pp. 169-182 ◽  
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Late Pleistocene ◽  
World Ocean ◽  
Oxygen Isotopic Composition ◽  
Stratigraphic Correlation ◽  
Equatorial Atlantic ◽  
Deep Sea Sediment ◽  
Oxygen Isotopic ◽  
Isotope Measurements

Oxygen isotope measurements have been made in foraminifera from over 60 deep-sea sediment cores. Taken together with the oxygen isotope measurements published by Emiliani from Caribbean and Equatorial Atlantic cores, this comprises a unique body of stratigraphic data covering most of the important areas of calcareous sediment over the whole world ocean. The oxygen isotopic composition of foraminifera from cores of Late Pleistocene sediment varies in a similar manner in nearly all areas; the variations reflect changes in the oxygen isotopic composition of the ocean. The oceans are mixed in about 1 ka so that ocean isotopic changes, resulting from fluctuations in the quantity of ice stored on the continents, must have occurred almost synchronously in all regions. Thus the oxygen isotope record provides an excellent means of stratigraphic correlation. Cores accumulated at rates of over about 5 cm/ka provide records of oxygen isotopic composition change that are almost unaffected by post-depositional mixing of the sediment. Thus they preserve a detailed record of the advance and retreat of the ice masses in the northern hemisphere, and provide a unique source of information for the study of ice-sheet dynamics.

Paleoclimatic Significance of the Stable Isotopic Composition and Petrology of a Late Pleistocene Stalagmite from Botswana

1995 ◽  
Vol 43 (3) ◽  
pp. 320-328 ◽  
Author(s):  
Karin Holmgren ◽  
Wibjörn Karlén ◽  
Paul A. Shaw
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Isotopic Composition ◽  
Late Pleistocene ◽  
Environmental Changes ◽  
Stable Isotopic ◽  
Dry Conditions ◽  
Paleoclimatic Significance ◽  
Second Period ◽  
Age Determinations

AbstractHigh-resolution δ18O and δ13C analyses of a stalagmite from Lobatse II Cave reveal late Pleistocene environmental changes in Botswana. Large shifts in δ18O and δ13C are observed between two main periods of deposition. The first period, between 51,000 and 43,000 yr B.P., was warm and humid and may have been associated with some C3 vegetation. The second period, between 27,000 and 21,000 yr B.P., had temperatures approximately 2°C lower, and vegetation dominated by drought-adapted C4 plants. The intervening period, between 43,000 and 27,000 yr B.P., bounded by two major hiatuses in stalagmite growth, produced discontinuous speleothem formation, probably under dry conditions. New 230 Th/234U mass spectrometry age determinations for the stalagmite generally agree with previously measured 230 Th/234U ages.

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.

scholarly journals Some clear evidences of the intrasedimental origin of massive ice in northern Eurasia

2020 ◽  
pp. 23-34
Author(s):  
Yurij Kirillovich Vasil'chuk
Keyword(s):  
Isotopic Composition ◽  
Late Pleistocene ◽  
Western Siberia ◽  
Ice Sheets ◽  
The Arctic ◽  
Northern Eurasia ◽  
Glacial Ice ◽  
Mountainous Regions ◽  
The North ◽  
Holocene Sediments

Massive ice is widespread on the territory of modern of Eurasian permafrost area: in the north of Western Siberia, Taimyr, Chukotka, and Arctic islands. Their thickness reaches 45-50m. The origin of massive ice is difficult to define due to the equifinality of such two different processes as intrasedimental freezing and formation of glacial ice. In both cases, thick massive ice is formed in various ways, but with the same final appearance. Three important aspects that show the evidence of the intrasedimental origin of massive ice in the north of Eurasia are examined. At first glance, they are obvious, but still fell out of sight of paleogeocryologists. It is shown that: 1) Any currently existing Late Pleistocene glacier, or part of it located under Holocene ice, have not yet been found within the Eurasian Arctic or on the Arctic islands with ice sheets, nor in the mountainous regions. 2) The isotopic composition of the vast majority of massive ice found in northern Eurasia is quite "Holocene", whereas in the north of Canada and Alaska, ice with a very light isotopic composition can often be found. 3) It should be taken into account that massive ice is found in the Holocene sediments of Western Siberia and Chukotka, where there is no reason to assume the glaciers spread to the plains.

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