scholarly journals U–Pb Dating and Isotopic Composition of the Tafresh Intrusions in the Central Part of UDMA, Iran: Implication for Petrogenesis, the Role of Crust-Mantle Interaction and Geodynamic Process

2020 ◽  
Author(s):  
Davood Raeisi ◽  
Shahrouz Babazadeh ◽  
Massimo D’Antonio ◽  
Miao Zhao ◽  
Zhiming Yang
Keyword(s):  
Isotopic Composition ◽  
Geodynamic Process

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

scholarly journals Experience in applying a local analysis an sulfur isotopes in the ore sulfides of the largest deposits of Bodaibinsky Synclinoria (Eastern Siberia)

2019 ◽  
Vol 484 (4) ◽  
pp. 460-463
Author(s):  
N. A. Goryachev ◽  
A. V. Ignatiev ◽  
T. A. Velivetskaya ◽  
A. E. Budyak ◽  
Yu. I. Tarasova
Keyword(s):  
Isotopic Composition ◽  
Sulfur Isotopes ◽  
Gold Deposits ◽  
Local Analysis ◽  
Eastern Siberia ◽  
The Law ◽  
Mass Dependent ◽  
Mass Dependent Fractionation

The experience of LA—ICP determining of the isotopic composition of sulfur pyrite and arsenopyrite of gold deposits of the Baikal-patomsky plateau is considered. The technique is characterized. It is shown that all the studied samples have values δ34S and δ33S strictly corresponding to the law of mass-dependent fractionation of sulfur isotopes. A regular alleviation of the isotopic composition of sulfur of pyrite as its crystals grow for Sukhoi Log and the isotopic homogeneity of pyrite and pyrrhotite of the Golets Vysokhashiy deposit are established. It is concluded that the possible role of metamorphism of the Mamsko-Oronsky belt in the formation of isotopic homogeneity of ore sulfides.

Authigenesis of native sulphur and dolomite in a lacustrine evaporitic setting (Hellín basin, Late Miocene, SE Spain)

2011 ◽  
Vol 148 (4) ◽  
pp. 655-669 ◽  
Author(s):  
J. LINDTKE ◽  
S. B. ZIEGENBALG ◽  
B. BRUNNER ◽  
J. M. ROUCHY ◽  
C. PIERRE ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Late Miocene ◽  
Heterotrophic Bacteria ◽  
Carbon Isotopic Composition ◽  
Sulphate Reduction ◽  
Se Spain ◽  
Carbon Isotopic ◽  
Bacterial Sulphate Reduction ◽  
Strong Depletion

AbstractAbundant sulphur is present in the Late Miocene evaporitic sequence of the lacustrine Hellín basin in SE Spain. Weathering of Triassic evaporites controlled the chemical composition of the Miocene lake. The lacustrine deposits comprise gypsum, marlstones, diatomites and carbonate beds. Sulphur-bearing carbonate deposits predominantly consist of early diagenetic dolomite. Abundant dolomite crystals with a spheroidal habit are in accordance with an early formation and point to a microbial origin. The carbon isotopic composition of the dolomite (δ13C values between −10 and −4‰) indicates mixing of lake water carbonate and carbonate derived from the remineralization of organic matter by heterotrophic bacteria. Dolomite precipitated syngenetically under evaporitic conditions as indicated by high oxygen isotope values (δ18O between +6 and +11‰). Nodules of native sulphur are found in gypsum, carbonate beds and marlstone layers. Sulphur formed in the course of microbial sulphate reduction, as reflected by its strong depletion in34S (δ34S values as low as −17‰). Near to the surface many of the sulphur nodules were in part or completely substituted by secondary gypsum, which still reflects the sulphur isotopic composition of native sulphur (−18 to −10‰). This study exemplifies the role of bacterial sulphate reduction in the formation of dolomite and native sulphur in a semi-enclosed lacustrine basin during Late Miocene time.

Role of Five Synthetic Reaction Conditions on the Stable Isotopic Composition of 3,4-Methylenedioxymethamphetamine

2010 ◽  
Vol 82 (13) ◽  
pp. 5484-5489 ◽  
Author(s):  
Hilary A. S. Buchanan ◽  
Niamh Nic Daéid ◽  
William J. Kerr ◽  
James F. Carter ◽  
Jenny C. Hill
Keyword(s):  
Isotopic Composition ◽  
Reaction Conditions ◽  
Stable Isotopic Composition ◽  
Stable Isotopic ◽  
Synthetic Reaction

Role of peat organic matter on isotopic composition of most abundant benthic organisms in intertidal habitats of SW Iceland

2008 ◽  
Vol 154 (1) ◽  
pp. 191-198 ◽  
Author(s):  
G. Sarà ◽  
C. Romano ◽  
M. De Pirro ◽  
P. H. Halldòrson ◽  
M. Sprovieri ◽  
...  
Keyword(s):  
Organic Matter ◽  
Isotopic Composition ◽  
Benthic Organisms ◽  
Intertidal Habitats

scholarly journals Measurement report: Spatial variability of northern Iberian rainfall stable isotope values – investigating atmospheric controls on daily and monthly timescales

2021 ◽  
Vol 21 (13) ◽  
pp. 10159-10177
Author(s):  
Ana Moreno ◽  
Miguel Iglesias ◽  
Cesar Azorin-Molina ◽  
Carlos Pérez-Mejías ◽  
Miguel Bartolomé ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Air Temperature ◽  
Isotope Composition ◽  
Significant Negative Correlation ◽  
Relative Role ◽  
Northern Spain ◽  
Mass Source ◽  
Highly Correlated

Abstract. For the first time, this article presents a large dataset of precipitation isotopic measurements (δ18Op and δ2Hp) sampled every day or 2 d from seven sites on a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to (1) characterize the rainfall isotopic variability in northern Spain at daily and monthly timescales and (2) assess the principal factors influencing rainfall isotopic variability. The relative role of air temperature and rainfall in determining the stable isotope composition of precipitation changes along the west-to-east transect, with air temperature being highly correlated with δ18Op at daily and monthly timescales, while a few sites along the transect show a significant negative correlation with precipitation. The highest air temperature–δ18Op dependency is found for a station located in the Pyrenees. Frontal systems associated with North Atlantic cyclones are the dominant mechanism inducing precipitation in this region, particularly in winter. This study allows an exploration of the role of air mass source and trajectory in determining the isotopic composition of rainfall in northern Iberia by characterizing the moisture uptake for three of the seven stations. The importance of continental versus marine moisture sources is evident, with clear seasonal and spatial variations. In addition, the type of precipitation (convective versus frontal rainfall) plays a key role, with convective rainfall associated with higher δ18Op values. This comprehensive spatiotemporal approach to analyzing the rainfall isotopic composition represents another step forward towards developing a more detailed, mechanistic framework for interpreting stable isotopes in rainfall as a paleoclimate and hydrological tracer.

Microbial sulfur cycling during the formation of Primary Lower Gypsum in Mediterranean marginals basins

2021 ◽  
Author(s):  
Laetitia Guibourdenche ◽  
Pierre Cartigny ◽  
Francesco Dela Pierre ◽  
Marcello Natalicchio ◽  
Giovanni Aloisi
Keyword(s):  
Isotopic Composition ◽  
Sulfur Cycling ◽  
Messinian Salinity Crisis ◽  
Sulfate Ion ◽  
Reduced Sulfur Compounds ◽  
Sulfur Isotopic Composition ◽  
Microbial Sulfate Reduction ◽  
Gypsum Formation ◽  
Wide Range

<p>During the first phase of the Messinian Salinity Crisis, massive amounts of sulfate (SO<sub>4</sub><sup>2-</sup>) have been sequestred in the form of up to 200m thick gypsum deposits (Primary Lower Gypsum) in Mediterranean marginal basins. The sulfur isotopic composition of the sulfate ion of this unit (δ<sup>34</sup>S<sub>SO4</sub>) (on average 22.3 ‰) strongly suggests that gypsum was formed by concentration of marine sulfate. Interestingly, the preservation of sulfide globules within the gypsum and marls interbeds suggests that the basin sulfate was not only involved in gypsum formation but a fraction was also reduced through microbial sulfate reduction. Moreover, filamentous fossils interpreted to be the remnants of sulfide oxidizing bacterias are entrapped in this gypsum and indicate, together with the occurrence of sulfide globules and dolomite, that an active biogeochemical sulfur cycling was active at the time of Primary Lower Gypsum deposition. To investigate the role of this active sulfur cycling in Mediterranean marginal basins, we analyzed the multiple sulfur isotopic composition of sulfate and sulfide minerals (δ<sup>34</sup>S andΔ<sup>33</sup>S)<sub></sub>from Primary Lower Gypsum of the Vena del Gesso basin (Italy). Whereas the isotopic composition of gypsum (δ<sup>34</sup>S<sub>SO4 </sub>from 21 to 24‰ and Δ<sup>33</sup>S<sub>SO4 </sub>from -0.001 to 0.049‰) display very homogenous values that are close to those of the Messinian ocean (δ<sup>34</sup>S<sub>MSC </sub>~22±0.2‰ and Δ<sup>33</sup>S<sub>MSC</sub>~0.039±0.015), the analyzed reduced sulfur compounds display a wide range of variability  with -36 to +9‰ in δ<sup>34</sup>S and -0.017 to 0.125‰ in Δ<sup>33</sup>S. This suggests huge hydrologically-driven redox variations during Primary Lower Gypsum deposition in the Vena del Gesso basin, possibly involving intermittent stratification of the water column and an active microbial cycling of sulfur.</p>

Sign in / Sign up

Export Citation Format

Share Document