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.

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 Oxygen isotope equilibrium in brachiopod shell fibres in the context of biological control

2008 ◽  
Vol 72 (1) ◽  
pp. 239-242 ◽  
Author(s):  
M. Cusack ◽  
A. Pérez-Huerta ◽  
P. Chung ◽  
D. Parkinson ◽  
Y. Dauphin ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Seawater Temperature ◽  
Environmental Data ◽  
Ambient Seawater ◽  
Secondary Layer ◽  
Vital Effect ◽  
Vital Effects ◽  
Stable Oxygen ◽  
Isotope Equilibrium

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

Relationship between δ18O and minor element composition of Terebratalia transversa

2007 ◽  
Vol 98 (3-4) ◽  
pp. 443-449 ◽  
Author(s):  
Maggie Cusack ◽  
David Parkinson ◽  
Alberto Pérez-Huerta ◽  
Jennifer England ◽  
Gordon B. Curry ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Seawater Temperature ◽  
Minor Element ◽  
Oxygen Isotope Composition ◽  
Secondary Layer ◽  
Vital Effects ◽  
Stable Oxygen ◽  
Temperature Proxy ◽  
Isotope Equilibrium

ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

scholarly journals Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign

2016 ◽  
Vol 16 (4) ◽  
pp. 2659-2673 ◽  
Author(s):  
Joël Savarino ◽  
William C. Vicars ◽  
Michel Legrand ◽  
Suzanne Preunkert ◽  
Bruno Jourdain ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Transfer Functions ◽  
Isotope Composition ◽  
Surface Ozone ◽  
Ice Core ◽  
Isotope Analysis ◽  
Austral Summer ◽  
Direct Observations ◽  
Atmospheric Nitrate ◽  
Stable Oxygen

Abstract. Variations in the stable oxygen isotope composition of atmospheric nitrate act as novel tools for studying oxidative processes taking place in the troposphere. They provide both qualitative and quantitative constraints on the pathways determining the fate of atmospheric nitrogen oxides (NO + NO2 = NOx). The unique and distinctive 17O excess (Δ17O = δ17O − 0.52 × δ18O) of ozone, which is transferred to NOx via oxidation, is a particularly useful isotopic fingerprint in studies of NOx transformations. Constraining the propagation of 17O excess within the NOx cycle is critical in polar areas, where there exists the possibility of extending atmospheric investigations to the glacial–interglacial timescale using deep ice core records of nitrate. Here we present measurements of the comprehensive isotopic composition of atmospheric nitrate collected at Dome C (East Antarctic Plateau) during the austral summer of 2011/2012. Nitrate isotope analysis has been here combined for the first time with key precursors involved in nitrate production (NOx, O3, OH, HO2, RO2, etc.) and direct observations of the transferrable Δ17O of surface ozone, which was measured at Dome C throughout 2012 using our recently developed analytical approach. Assuming that nitrate is mainly produced in Antarctica in summer through the OH + NO2 pathway and using concurrent measurements of OH and NO2, we calculated a Δ17O signature for nitrate on the order of (21–22 ± 3) ‰. These values are lower than the measured values that ranged between 27 and 31 ‰. This discrepancy between expected and observed Δ17O(NO3−) values suggests the existence of an unknown process that contributes significantly to the atmospheric nitrate budget over this East Antarctic region. However, systematic errors or false isotopic balance transfer functions are not totally excluded.

scholarly journals 14C Analyses of Groundwater From the Botucatu Aquifer System in Brazil

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 926-933 ◽  
Author(s):  
Annkarin Aurelia ◽  
Kimmelmann E Silva ◽  
Aldo da Cunha Rebouças ◽  
Maria Marlucia ◽  
Freitas Santiago
Keyword(s):  
Stable Isotope ◽  
Oxygen Isotope ◽  
Gradual Increase ◽  
Isotope Composition ◽  
Stable Isotope Composition ◽  
Stable Oxygen Isotope ◽  
Aquifer System ◽  
Groundwater Samples ◽  
Stable Oxygen ◽  
Different Origins

Measurements of 14C activity as well as determinations of the stable isotope composition (18O, 2H and 13C) of groundwater samples were made to investigate the flow path, origin, recharge and age of the Botucatu Aquifer System in Brazil, between 1984 and 1987. The stable oxygen isotope composition reflects infiltration during several climatic recharge conditions. Measured 14C activities range from 0.4 to 94.2% modern. δ13C values enable us to distinguish two groundwater types of different origins. There is a gradual increase of 14C ages from the outcrop area towards the central part of the basin, associated with a progression of the confining conditions. Anomalous fluoride contents seem to be correlated with high 14C ages of the groundwater. The reliability of the 14C data is discussed.

Interannual trends in stable oxygen isotope composition in precipitation of China during 1979–2007: Spatial incoherence

2017 ◽  
Vol 454 ◽  
pp. 25-37 ◽  
Author(s):  
Sen Yang ◽  
Mingjun Zhang ◽  
Shengjie Wang ◽  
Yangmin Liu ◽  
Fang Qiang ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Oxygen Isotope Composition ◽  
Stable Oxygen Isotope ◽  
Stable Oxygen
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