GEMSFITS: Code package for optimization of geochemical model parameters and inverse modeling

Miron, George Dan; Kulik, Dmitrii A.; Dmytrieva, Svitlana V.; Wagner, Thomas

doi:10.1016/j.apgeochem.2014.10.013

Cited by 29 publications

(16 citation statements)

References 62 publications

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“…The standard state Gibbs energies of aqueous species were regressed with the GEMSFITS code (Miron et al, 2015); http://gems.web.psi.ch/GEMSFITS, which uses the GEMS3K Gibbs energy minimization code (Kulik et al, 2013) and the TsolMod library of activity and equation of state models (Wagner et al, 2012). The chemical system definitions (lists of phases and species; initial thermodynamic properties of each species; bulk composition, pressure and temperature for each experimental data point) were prepared using the GEM-Selektor v.3 code (GEMS3) package (http://gems.web.psi.ch/GEMS3) and then exported into text files that can be read by GEMS3K and GEMSFITS codes (Miron et al, 2015). The starting composition of each experimental data point was specified in terms of the amounts of oxides, water and salts.…”

Section: Parameter Optimization Methodsmentioning

confidence: 99%

“…To reproduce those experiments where the actual bulk composition is not directly reported in GEMSFITS (Miron et al, 2015) and GEMS3 (Kulik et al, 2013), the nested regression functionality of GEMSFITS was used. This makes it possible to iteratively adjust the input composition (e.g., amounts of HCl and NaOH) in such a way that reported output compositions (e.g., pH or amount of H + ) are reproduced.…”

Section: 298mentioning

confidence: 99%

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Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Miron

Wagner

Kulik

et al. 2016

Geochimica et Cosmochimica Acta

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A large amount of critically evaluated experimental data on mineral solubility, covering the entire Na-K-Al-Si-O-H-Cl system over wide ranges in temperature and pressure, was used to simultaneously refine the standard state Gibbs energies of aqueous ions and complexes in the framework of the revised Helgeson-Kirkham-Flowers equation of state. The thermodynamic properties of the solubility-controlling minerals were adopted from the internally consistent dataset of Holland and Powell (2002; Thermocalc dataset ds55). The global optimization of Gibbs energies of aqueous species, performed with the GEMSFITS code (Miron et al., 2015), was set up in such a way that the association equilibria for ion pairs and complexes, independently derived from conductance and potentiometric data, are always maintained. This was achieved by introducing reaction constraints into the parameter optimization that adjust Gibbs energies of complexes by their respective Gibbs energy effects of reaction, whenever the Gibbs energies of reactant species (ions) are changed. The optimized thermodynamic dataset is reported with confidence intervals for all parameters evaluated by Monte Carlo trial calculations. The new thermodynamic dataset is shown to reproduce all available fluid-mineral phase equilibria and mineral solubility data with good accuracy and precision over wide ranges in temperature (25 to 800°C), pressure (1 bar to 5 kbar) and composition (salt concentrations up to 5 molal). The global data optimization process adopted in this study can be readily repeated any time when extensions to new chemical elements and species are needed, when new experimental data become available, or when a different aqueous activity model or equation of state should be used. This work serves as a proof of concept that our optimization strategy is feasible and successful in generating a thermodynamic dataset reproducing all fluidmineral and aqueous speciation equilibria in the Na-K-Al-Si-O-H-Cl system within their experimental uncertainties. The new dataset resolves the long-standing discrepancies between thermodynamic data of minerals and those of aqueous ions and complexes, by achieving an astonishing degree of consistency between a large number of fluid-mineral equilibrium data. All of this at the expense of changing the standard state properties of aqueous species, manly the Gibbs energy of formation. Using the same strategy, the core dataset for the system Na-K-Al-Si-O-H-Cl can be extended with additional rock-forming elements such as Ca, Mg, Fe, Mn, Ti, S, C, B. In future, the standard-state properties of minerals and aqueous species should be simultaneously optimized, to create the next-generation of fully internally consistent data for fluid-mineral equilibria. Although we employ the widely used HKF equations for this study, the same computational approach can be readily applied to any other speciation-based equation of state for multicomponent aqueous solutions.

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Section: Parameter Optimization Methodsmentioning

confidence: 99%

Section: 298mentioning

confidence: 99%

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Miron

Wagner

Kulik

et al. 2016

Geochimica et Cosmochimica Acta

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“…K, Na, Al, U, Sr) in their respective sites; (2) generating all possible end members; and (3) parameterizing endmembers based on available solubility, element uptake, and spectroscopic data (e.g. using the GEMSFITS code[106]) and are the subjects of ongoing research.For the calcium silicate hydrate complexes, CaH 3 SiO 4 + (CaHSiO 3 + +2H 2 O) and CaH 2 SiO 4 0 (CaSiO 3 ), the reported complex formation data show a significant scatter. In particular, complex…”

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confidence: 99%

Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Lothenbach

Kulik

Matschei

et al. 2019

Cement and Concrete Research

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319

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Thermodynamic modelling can reliably predict hydrated cement phase assemblages and chemical compositions, including their interactions with prevailing service environments, provided an accurate and complete thermodynamic database is used. Here, we summarise the Cemdata18 database, which has been developed specifically for hydrated Portland, calcium aluminate, calcium sulfoaluminate and blended cements, as well as for alkali-activated materials. It is available in GEMS and PHREEQC computer program formats, and includes thermodynamic properties determined from various experimental data published in recent years. Cemdata18 contains thermodynamic data for common cement hydrates such as C-S-H, AFm and AFt phases, hydrogarnet, hydrotalcite, zeolites, and M-S-H that are val-Cemdata18 includes a comprehensive selection of cement hydrates commonly encountered in Portland cement (PC) systems in the temperature range of to 100°C, including calcium silicate hydrate (C-S-H), magnesium silicate hydrate (M-S-H), hydrogarnet, hydrotalcite-like phases, some zeolites, AFm and AFt phases, and various solid solutions used to describe the solubility of these phases. Solubility constants have generally been calculated based on critical reviews of all available experimental data and from additional experiments made either to obtain missing data or to verify existing data. Additional solubility data were measured and compiled using temperatures ranging from 0 to 100°C in many instances, as documented in [9, 12, 27, 28]. Numerous solid solutions among AFm and AFt phases, siliceous hydrogarnets, hydrotalcite-like phases, C-S-H, and M-S-H have been observed and are included in Cemdata18. Several C-S-H solid solution models, as well as two models for hydroxide-hydrotalcite are available in Cemdata18. The CSHQ model from [11] and the OH-hydrotalcite end member with Mg/Al = 2 are well adapted for PC. Although the CSHQ model is able to describe the entire range of Ca/Si ratios encountered, it is best used for high Ca/Si C-S-H, as it still lacks the ability to predict aluminium uptake, which is of less importance for Portland cements than for blended cements. For alkali activated binders, the calcium (alkali) aluminosilicate hydrate (C-(N-)A-S-H) gel model, with lower calcium but higher aluminium and alkali content than in the C-S-H type phase which exists in hydrated PC, and a Mg-Al layered double hydroxide with variable Mg/Al ratio, are available. This paper summarises Cemdata18, which includes the most important additions to the Cemdata07 and Cemdata14 databases in recent years. It also discusses the relevance and implications of these additions, and compares Cemdata07 and Cemdata18, accounting for their main differences. Summaries

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“…A detailed list of minerals, aqueous species, and gases used from this database for the Ca-C-Na-Cl-O-H-REE components system can be found in Table 2. This dataset comprises mineral data from Holland and Powell [55] and aqueous species from SUPCRT92 [36,57,63,64], with the recently updated internally consistent dataset of Miron et al [58] using the GEMSFITS code package [65]. Experimental data for REE chloride aqueous species were implemented using data from the study of Migdisov et al [35], the HCl dissociation constants of Tagirov et al [59], and the properties of REE(OH) 3 (s) compiled in the study of Navrotsky et al [56].…”

Section: Thermodynamic Dataset and Activity Modelsmentioning

confidence: 99%

Rare Earth Elements in Mineral Deposits: Speciation in Hydrothermal Fluids and Partitioning in Calcite

Perry

Gysi

2018

Geofluids

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is properly cited.Studying the speciation and mineral-fluid partitioning of the rare earth elements (REE) allows us to delineate the key processes responsible for the formation of economic REE mineral deposits in natural systems. Hydrothermal REE-bearing calcite is typically hosted in carbonatites and alkaline rocks, such as the giant Bayan Obo REE deposit in China and potential REE deposits such as Bear Lodge, WY. The compositions of these hydrothermal veins yield valuable information regarding pressure ( ), temperature ( ), salinity, and other physicochemical conditions under which the REE can be fractionated and concentrated in crustal fluids. This study presents numerical simulation results of the speciation of REE in aqueous NaCl-H 2 O-CO 2 -bearing hydrothermal fluids and a new partitioning model between calcite and fluids at different --conditions. Results show that, in a high CO 2 and low salinity system, bicarbonate/carbonate are the main transporting ligands for the REE, but predominance shifts to chloride complexes in systems with high CO 2 and high salinity. Hydroxyl REE complexes may be important for the solubility and transport of the REE in alkaline fluids. These numerical predictions allow us to make quantitative interpretations of hydrothermal processes in REE mineral deposits, particularly in carbonatites, and show where future experimental work will be essential in improving our modeling capabilities for these ore-forming processes.

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GEMSFITS: Code package for optimization of geochemical model parameters and inverse modeling

Cited by 29 publications

References 62 publications

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Cemdata18: A chemical thermodynamic database for hydrated Portland cements and alkali-activated materials

Rare Earth Elements in Mineral Deposits: Speciation in Hydrothermal Fluids and Partitioning in Calcite

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