Sulfur Isotope Partitioning in Metallic Sulfide Systems

1971 ◽  
Vol 8 (11) ◽  
pp. 1397-1408 ◽  
Author(s):  
Y. Kajiwara ◽  
H. R. Krouse
Keyword(s):  
Sulfur Isotope ◽  
Equilibrium Constants ◽  
Isotopic Fractionation ◽  
Exchange Constant ◽  
Equilibrium Exchange ◽  
Direct Measurements ◽  
Theoretical Predictions ◽  
Mineral Pair ◽  
Isotope Partitioning ◽  
Fractionation Factors

Sulfur isotopic fractionation factors involving pairs of pyrite, pyrrhotite, sphalerite, chalcopyrite, and galena have been determined experimentally over the temperature range 250 °C to 600 °C.Since chalcopyrite and pyrrhotite are not stable at higher PS2 conditions, buffer assemblages were necessary to control PS2 in experiments with these minerals. Since low PS2 values and low temperatures are unfavorable to rapid isotope exchange, techniques were devised whereby equilibrium constants could be estimated indirectly in systems where direct measurements are not possible because of the time factor.Current data place the sulfide minerals in the following order of 34S enrichment under equilibrium exchange conditions: pyrite > (pyrrhotite [Formula: see text]sphalerite) > chalcopyrite > galena in agreement with theoretical predictions. In agreement with theory the equilibrium exchange constant K for a given mineral pair depends upon temperature as follows: 1000 ln [Formula: see text], where A denotes a constant. The A values for various mineral pairs have been determined with ± 10% uncertainties as follows: 11.0 × 105 (py–gn), 8.0 × 105 (sp–gn), 6.5 × 105 (cp–gn), 4.5 × 105 (py–cp), 3.0 × 105 (py–sp, py–po), 1.5 × 105 (sp–cp, po–cp), and [Formula: see text] 0 (sp–po).

scholarly journals Significant Zr isotope variations in single zircon grains recording magma evolution history

2020 ◽  
Vol 117 (35) ◽  
pp. 21125-21131 ◽  
Author(s):  
Jing-Liang Guo ◽  
Zaicong Wang ◽  
Wen Zhang ◽  
Frédéric Moynier ◽  
Dandan Cui ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Major Type ◽  
Strong Temperature Dependence ◽  
Calc Alkaline ◽  
Southern Tibet ◽  
Rayleigh Distillation ◽  
Single Zircon ◽  
Magmatic History ◽  
Fractionation Factors

Zircons widely occur in magmatic rocks and often display internal zonation finely recording the magmatic history. Here, we presented in situ high-precision (2SD <0.15‰ for δ94Zr) and high–spatial-resolution (20 µm) stable Zr isotope compositions of magmatic zircons in a suite of calc-alkaline plutonic rocks from the juvenile part of the Gangdese arc, southern Tibet. These zircon grains are internally zoned with Zr isotopically light cores and increasingly heavier rims. Our data suggest the preferential incorporation of lighter Zr isotopes in zircon from the melt, which would drive the residual melt to heavier values. The Rayleigh distillation model can well explain the observed internal zoning in single zircon grains, and the best-fit models gave average zircon–melt fractionation factors for each sample ranging from 0.99955 to 0.99988. The average fractionation factors are positively correlated with the median Ti-in-zircon temperatures, indicating a strong temperature dependence of Zr isotopic fractionation. The results demonstrate that in situ Zr isotope analyses would be another powerful contribution to the geochemical toolbox related to zircon. The findings of this study solve the fundamental issue on how zircon fractionates Zr isotopes in calc-alkaline magmas, the major type of magmas that led to forming continental crust over time. The results also show the great potential of stable Zr isotopes in tracing magmatic thermal and chemical evolution and thus possibly continental crustal differentiation.

scholarly journals Dating of Groundwater Recharge in Two Small Adjacent Aquifers in Israel and Their Initial 14C Activities

Radiocarbon ◽  
2011 ◽  
Vol 53 (1) ◽  
pp. 137-149 ◽  
Author(s):  
J Guttman ◽  
J Kronfeld ◽  
I Carmi
Keyword(s):  
Groundwater Recharge ◽  
Unsaturated Zone ◽  
Hydraulic Properties ◽  
Isotopic Fractionation ◽  
Apparent Difference ◽  
Pleistocene Aquifer ◽  
Fractionation Factors

Radiocarbon and tritium determinations were carried out in 2 adjacent small aquifers in Israel. These aquifers have small storage capacities and good hydraulic properties. Darcy calculations suggest that the aquifers contain young waters, ≃50 yr in age. 14C concentrations in the Pleistocene aquifer are between 23–60 pMC, with the lowest activity related to contamination by petroleum-based fertilizers with no 14C. 14C concentrations in the Judea Group aquifer range from 62 to 95 pMC. An apparent difference of ≃1000 yr is indicated for the average recharge age between the 2 aquifers. The tritium data suggests that the water in both aquifers is quite young. The 1000-yr difference is an artifact of initial isotopic fractionation differences through the unsaturated zone as established elsewhere for these 2 aquifers. When these individual fractionation factors (0.54 for the Pleistocene and 0.62 for the Judea Group) are used, it is revealed that both aquifers contain young water, in agreement with the Darcy calculation, which was recharged at the beginning of the period of thermonuclear atmospheric testing in the early 1960s.

Structures and isotopic fractionation factors of complexes AHA-1

1977 ◽  
Vol 99 (15) ◽  
pp. 5207-5209 ◽  
Author(s):  
Maurice M. Kreevoy ◽  
Tai-Ming Liang ◽  
Kwang-Chou Chang
Keyword(s):  
Isotopic Fractionation ◽  
Fractionation Factors

Sulfur isotope fractionation by Proteus vulgaris and Salmonella heidelberg during the reduction of thiosulfate

1980 ◽  
Vol 26 (10) ◽  
pp. 1173-1177 ◽  
Author(s):  
R. G. L. McCready ◽  
V. A. Grinenko ◽  
H. R. Krouse
Keyword(s):  
Isotope Fractionation ◽  
Sulfur Isotope ◽  
Isotope Composition ◽  
Isotopic Fractionation ◽  
Proteus Vulgaris ◽  
Sulfane Sulfur ◽  
Sulfur Isotope Fractionation ◽  
Fractionation Pattern ◽  
High Concentrations ◽  
Salmonella Heidelberg

Proteus vulgaris metabolized thiosulfate to H2S. The amount evolved and its sulfur isotope composition identified it solely with sulfane sulfur. In contrast. Salmonella heidelberg sequentially reduced the sulfane sulfur of S2O32− with slight enrichment of the evolved sulfide in 32S and then reduced the sulfonate sulfur of S2O32− with large isotopic selectivities and an inverse isotopic fractionation pattern. The inverse isotope fractionation pattern for the H2S derived from the sulfonate sulfur was almost identical to that observed during the reduction of high concentrations of sulfite by S. heidelberg.

scholarly journals Decay of isotropic turbulence in the initial period

1948 ◽  
Vol 193 (1035) ◽  
pp. 539-558 ◽  
Keyword(s):  
Correlation Function ◽  
Isotropic Turbulence ◽  
Initial Period ◽  
Rate Of Change ◽  
Velocity Correlation ◽  
Integral Scale ◽  
Direct Measurements ◽  
Theoretical Predictions ◽  
History Of ◽  
Velocity Correlation Functions

In a previous paper the authors described direct measurements of all the terms in the equation for the rate of change of mean square vorticity in isotropic turbulence. The present paper is concerned with developments arising from the earlier work and with the experimental verification of some recent theoretical investigations. The results of measurements of the turbulent intensity u ' and of λ are presented; these establish that u' -2 and λ 2 are each proportional to the time of decay provided that the time is not too large. Within this initial period of the decay, the double and triple velocity correlation functions are found to maintain their form, i.e. to be self-preserving, for small values of the distance r between the two points at which the correlations are taken. For larger separations the double velocity correlation function changes its form slightly during decay and direct measurements of λ and of the integral scale L show that λ/ L increases during the decay. Theoretical predictions about the shape of the correlation function, for limited ranges of r , at high and at low Reynolds numbers are compared with measurements. Theory has shown that the above decay law cannot persist indefinitely, and the present experiments confirm that the decay law changes in the expected direction when the time is large. A division of the life-history of the turbulence into initial, transition and final periods is suggested; within the initial period, a classification based on the Reynblds number is also possible. Some speculations on the interpretation of the initial period are presented.

MICROBIAL CONTROLS ON SULFUR ISOTOPE PARTITIONING UNDER LOW-NUTRIENT CONDITIONS

2016 ◽  
Author(s):  
Max Giannetta ◽  
◽  
Robert A. Sanford ◽  
Jennifer L. Druhan
Keyword(s):  
Sulfur Isotope ◽  
Isotope Partitioning ◽  
Nutrient Conditions
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