Isotopic fractionation during congruent dissolution, precipitation and at equilibrium: Evidence from Mg isotopes

2012 ◽  
Vol 92 ◽  
pp. 170-183 ◽  
Author(s):  
Christopher R. Pearce ◽  
Giuseppe D. Saldi ◽  
Jacques Schott ◽  
Eric H. Oelkers
Keyword(s):  
Isotopic Fractionation ◽  
Congruent Dissolution ◽  
Mg Isotopes

scholarly journals Diffusive processes in aqueous glass dissolution

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Thomas L. Goût ◽  
Sambuddha Misra ◽  
Edward T. Tipper ◽  
Madeleine S. Bohlin ◽  
Rui Guo ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Diffusive Transport ◽  
Glass Dissolution ◽  
Post Process ◽  
Significant Process ◽  
Congruent Dissolution ◽  
High Level Nuclear Waste ◽  
Significant Mechanism ◽  
High Level ◽  
Diffusive Processes

AbstractHigh level nuclear waste is often immobilised in a borosilicate glass for disposal. However, this glass corrodes in contact with aqueous solutions. To predict radionuclide releases from wasteforms, their dissolution mechanisms must be understood. Understanding glass dissolution mechanisms presents a challenge across numerous other disciplines and many glass dissolution models still remain conflicted. Here we show that diffusion was a significant process during the later stages of dissolution of a simplified waste glass but was not evidenced during the initial stages of dissolution. The absence of measurable isotopic fractionation in solution initially supports models of congruent dissolution. However, the solution becoming isotopically lighter at later times evidences diffusive isotopic fractionation and opposes models that exclude diffusive transport as a significant mechanism. The periodically sampled isotopic methodologies outlined here provide an additional dimension with which to understand glass dissolution mechanisms beyond the usual measurement of solution concentrations and, post-process, nano-scale analysis of the altered glass.

scholarly journals Magnesium stable isotopes support the lunar magma ocean cumulate remelting model for mare basalts

2018 ◽  
Vol 116 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Fatemeh Sedaghatpour ◽  
Stein B. Jacobsen
Keyword(s):  
Isotopic Composition ◽  
Isotopic Fractionation ◽  
The Moon ◽  
Magma Ocean ◽  
Isotopic Analyses ◽  
Lunar Samples ◽  
Lunar Basalts ◽  
Mg Isotopes ◽  
Isotopic Variations ◽  
Mare Basalts

We report high-precision Mg isotopic analyses of different types of lunar samples including two pristine Mg-suite rocks (72415 and 76535), basalts, anorthosites, breccias, mineral separates, and lunar meteorites. The Mg isotopic composition of the dunite 72415 (δ25Mg = −0.140 ± 0.010‰, δ26Mg = −0.291 ± 0.018‰), the most Mg-rich and possibly the oldest lunar sample, may provide the best estimate of the Mg isotopic composition of the bulk silicate Moon (BSM). This δ26Mg value of the Moon is similar to those of the Earth and chondrites and reflects both the relative homogeneity of Mg isotopes in the solar system and the lack of Mg isotope fractionation by the Moon-forming giant impact. In contrast to the behavior of Mg isotopes in terrestrial basalts and mantle rocks, Mg isotopic data on lunar samples show isotopic variations among the basalts and pristine anorthositic rocks reflecting isotopic fractionation during the early lunar magma ocean (LMO) differentiation. Calculated evolutions of δ26Mg values during the LMO differentiation are consistent with the observed δ26Mg variations in lunar samples, implying that Mg isotope variations in lunar basalts are consistent with their origin by remelting of distinct LMO cumulates.

Magnesium isotopic fractionation during basalt differentiation as recorded by evolved magmas

2021 ◽  
Vol 565 ◽  
pp. 116954
Author(s):  
Xiao-Jun Wang ◽  
Li-Hui Chen ◽  
Takeshi Hanyu ◽  
Yuan Zhong ◽  
Jin-Hua Shi ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Basalt Differentiation

scholarly journals Numerical Phase-Field Model Validation for Dissolution of Minerals

2021 ◽  
Vol 11 (6) ◽  
pp. 2464
Author(s):  
Sha Yang ◽  
Neven Ukrainczyk ◽  
Antonio Caggiano ◽  
Eddie Koenders
Keyword(s):  
Phase Field ◽  
Liquid Interface ◽  
Mineral Dissolution ◽  
Experimental Results ◽  
Wide Range ◽  
Congruent Dissolution ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Dissolution Of Minerals ◽  
Meso Scale

Modelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism.

scholarly journals Isotopic Fractionation Accompanying CO2 Hydroxylation and Carbonate Precipitation from High pH Waters at The Cedars, California, USA

2021 ◽  
Author(s):  
John N. Christensen ◽  
James M. Watkins ◽  
Laurent S. Devriendt ◽  
Donald J. DePaolo ◽  
Mark E. Conrad ◽  
...  
Keyword(s):  
Isotopic Fractionation ◽  
Carbonate Precipitation ◽  
High Ph

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 Quantum Genetic Terrain Algorithm (Q-GTA): A Technique to Study the Evolution of the Earth Using Quantum Genetic Algorithm

Proceedings ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 26
Author(s):  
Pranjal Sharma ◽  
Ankit Agarwal ◽  
Bhawna Chaudhary
Keyword(s):  
Genetic Algorithm ◽  
Isotopic Fractionation ◽  
Volcanic Eruptions ◽  
Temperature Characteristic ◽  
Isotopic Ratios ◽  
Mantle Lithosphere ◽  
Monitoring Networks ◽  
Temperature Changes ◽  
Quantum Genetic Algorithm ◽  
The Earth

In recent years, geologists have put in a lot of effort trying to study the evolution of Earth using different techniques studying rocks, gases, and water at different channels like mantle, lithosphere, and atmosphere. Some of the methods include estimation of heat flux between the atmosphere and sea ice, modeling global temperature changes, and groundwater monitoring networks. That being said, algorithms involving the study of Earth’s evolution have been a debated topic for decades. In addition, there is distinct research on the mantle, lithosphere, and atmosphere using isotopic fractionation, which this paper will take into consideration to form genes at the former stage. This factor of isotopic fractionation could be molded in QGA to study the Earth’s evolution. We combined these factors because the gases containing these isotopes move from mantle to lithosphere or atmosphere through gaps or volcanic eruptions contributing to it. We are likely to use the Rb/Sr and Sm/Nd ratios to study the evolution of these channels. This paper, in general, provides the idea of gathering some information about temperature changes by using isotopic ratios as chromosomes, in QGA the chromosomes depict the characteristic of a generation. Here these ratios depict the temperature characteristic and other steps of QGA would be molded to study these ratios in the form of temperature changes, which would further signify the evolution of Earth based on the study that temperature changes with the change in isotopic ratios. This paper will collect these distinct studies and embed them into an upgraded quantum genetic algorithm called Quantum Genetic Terrain Algorithm or Quantum GTA.

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