scholarly journals Oxygen isotope composition of the ice wedges of Ayon Island and Late Pleistocene and Holocene palaeotemperature reconstruction of the Northern Chukotka

2017 ◽  
pp. 92-104
Author(s):  
Yu. K. Vasil’Chuk ◽  
A. C. Vasil’Chuk
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Late Pleistocene ◽  
Isotope Composition ◽  
Oxygen Isotope Composition ◽  
Geochemical Characteristics ◽  
The Holocene ◽  
Temperature Reconstructions ◽  
Ice Wedge ◽  
Kolyma River

Syngenetic ice wedges have been investigated in the Ayon Island. Their isotopic composition, geochemical characteristics of both ice wedges and enclosing sediment have been obtained; four ice-wedges stages have been distinguished. Paleo temperature reconstructions for Ayon Island and adjacent territories of northern Chukotka have been yielded at the basis of these results. It is observed almost identical trends in the distribution of ice-wedge isotopic characteristics in the island and in the lower reaches of the Kolyma River, as well as differences in the magnitude of isotopic oscillations during the transition from Late Pleistocene to the Holocene as compared to ice-wedges of the Lower Kolyma region.

scholarly journals Technical Note: Silica stable isotopes and silicification in a carnivorous sponge \\textit{Asbestopluma} sp.

2014 ◽  
Vol 11 (12) ◽  
pp. 16573-16597
Author(s):  
K. R. Hendry ◽  
G. E. A. Swann ◽  
M. J. Leng ◽  
H. J. Sloane ◽  
C. Goodwin ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
The Body ◽  
Oxygen Isotope Composition ◽  
Silicon Isotope ◽  
Deep Seawater ◽  
Differential Distribution ◽  
Sponge Spicule

Abstract. The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotopic composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the biological vital effects on silica silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that appear related to unusual spicule silicification. The largest variation in both isotope systems was associated to the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence of an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotopic signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotopic signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

scholarly journals New oxygen isotope diagrams of late pleistocene and holocene ice wedges of Mamontova Gora and Syrdah Lake, Central Yakutia

2019 ◽  
Vol 486 (3) ◽  
pp. 365-370
Author(s):  
Yu. K. Vasil'chuk ◽  
D. G. Shmelev ◽  
M. Yu. Cherbunina ◽  
N. A. Budantseva ◽  
A. V. Broushkov ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Late Pleistocene ◽  
Air Temperature ◽  
Isotope Composition ◽  
Growth Period ◽  
Winter Conditions ◽  
Ice Wedge ◽  
Stable Oxygen ◽  
Lake Site ◽  
Winter Air Temperature

The aim of the study was to obtain the data of stable oxygen isotope composition of Late Pleistocene and Holocene ice wedges of Mamontova Gora and Syrdakh exposures and their chronology, and reconstruction of winter air temperature during the time of ice wedge formation. Direct dating of organic microinclusions from the ice wedges of Mamontova Gora outcrops allowed to establish that the ice wedges are younger than 20 ka, but older than 10 ka BP. δ18O values of the Late Pleistocene ice wedges of Mamontova Gora vary from -24.7 to -30.9 ‰, δ18O values of the Holocene ice wedges of this exposures range from -23.2 to -25.9 ‰. δ18O values in the Late Pleistocene ice wedges near Syrdakh Lake vary from -29.2 to -32.5 ‰. Reconstructed mean winter air temperature during the most part of the ice wedge growth period in Mamontova Gora site within Late Pleistocene varied from -28 to - 31°C, mean January temperature reached -42, -46°C, for the Syrdakh Lake site Late Pleistocene winter conditions were more severe: mean winter air temperature varied from -30 to -32°C, mean January air temperature reached -44, -48°C. Holocene mean winter air temperature were higher and varied from -24 to - 28°C, mean January temperature varied from -36 to -42°C.

The Oxygen Isotope Composition of Late Pleistocene and Holocene Ice Wedges of Kotelny Island

2018 ◽  
Vol 482 (1) ◽  
pp. 1216-1220
Author(s):  
Yu. K. Vasil’chuk ◽  
V. M. Makeev ◽  
A. A. Maslakov ◽  
N. A. Budantseva ◽  
A. C. Vasil’chuk ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Late Pleistocene ◽  
Isotope Composition ◽  
Oxygen Isotope Composition

scholarly journals Lubavinskoe Au-bearing ore deposit: petrochemical features of rocks and ores, and the origin conditions (Eastern Transbakalia)

2019 ◽  
Vol 485 (6) ◽  
pp. 713-719
Author(s):  
B. N. Abramov ◽  
V. Ph. Posohov ◽  
Yu. A. Kalinin
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Isotope Composition ◽  
Isotopic Ratio ◽  
Ore Deposits ◽  
Oxygen Isotope Composition ◽  
Magmatic Fluid ◽  
Tectonic Zone ◽  
Ore Deposit ◽  
Productive Phase

Lubavinskoe Au-bearing ore deposit is situated to submeridional deep layered tectonic zone. In these zones the ore veins are associated with small Mesozoic stocks of granodiorite and rocks of the dyke complexes of the sublatitudinal spread. According to geochemical features these intrusions are correspond to adacits. The proportion isotopic ratio of the oxygen and strontium at granodiorites indicates to their origin due to mantle-core interaction. Calculated oxygen isotope composition δ18 in the fluid in equilibrium with quartz in the productive phase 220-280 °С changes from 3,59 to 9.59‰, which corresponds to water of magmatic fluid nature. This is confirmed by the isotopic composition of sulfar for sulphides δ34S, ‰ from +0.7 to +6.7‰, corresponding to hydrothermal orogenic ore deposits.

scholarly journals Technical Note: Silica stable isotopes and silicification in a carnivorous sponge <i>Asbestopluma</i> sp.

2015 ◽  
Vol 12 (11) ◽  
pp. 3489-3498 ◽  
Author(s):  
K. R. Hendry ◽  
G. E. A. Swann ◽  
M. J. Leng ◽  
H. J. Sloane ◽  
C. Goodwin ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Oxygen Isotope ◽  
Isotope Composition ◽  
The Body ◽  
Oxygen Isotope Composition ◽  
Silicon Isotope ◽  
Deep Seawater ◽  
Differential Distribution ◽  
Sponge Spicule ◽  
Isotope Signature

Abstract. The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotope composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the vital effects on silica, silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that are related to unusual spicule silicification. The largest variation in both isotope systems was associated with the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotope signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotope signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

scholarly journals Oxygen isotope composition in extant shark teeth as a proxy to temperature reconstructions

2021 ◽  
Author(s):  
Zivile Zigaite ◽  
Martin Whitehouse ◽  
Carlos Oliveira ◽  
Ivan Sansom ◽  
Matthew Cowen ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Oxygen Isotope Composition ◽  
Shark Teeth ◽  
Temperature Reconstructions
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