Konrad-Schmolke, M and Halama, R (2014) Combined thermodynamic-geochemical modeling in metamorphic geology: Boron as tracer of fluid-rock interaction. Lithos, 208. 393 -414. ISSN 0024-4937

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Konrad-Schmolke & Halama 2014 Thermodynamic-geochemical modeling in metamorphic geology (accepted MS).pdf - Accepted Version
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Quantitative geochemical modeling is today applied in a variety of geological environments from the petrogenesis of igneous rocks to radioactive waste disposal. In addition, the development of thermodynamic databases and computer programs to calculate equilibrium phase diagrams has greatly advanced our ability to model geodynamic processes. Combined with experimental data on elemental partitioning and isotopic fractionation, thermodynamic forward modeling unfolds enormous capacities that are far from exhausted.

In metamorphic petrology the combination of thermodynamic and trace element forward modeling can be used to study and to quantify processes at spatial scales from μm to km. The thermodynamic forward models utilize Gibbs energy minimization to quantify mineralogical changes along a reaction path of a chemically open fluid/rock system. These results are combined with mass balanced trace element calculations to determine the trace element distribution between rock and melt/fluid during the metamorphic evolution. Thus, effects of mineral reactions, fluid–rock interaction and element transport in metamorphic rocks on the trace element and isotopic composition of minerals, rocks and percolating fluids or melts can be predicted.

Here we illustrate the capacities of combined thermodynamic–geochemical modeling based on two examples relevant to mass transfer during metamorphism. The first example focuses on fluid–rock interaction in and around a blueschist-facies shear zone in felsic gneisses, where fluid-induced mineral reactions and their effects on boron (B) concentrations and isotopic compositions in white mica are modeled. In the second example, fluid release from a subducted slab, the associated transport of B as well as variations in B concentrations and isotopic compositions in liberated fluids and residual rocks are modeled. We compare the modeled results of both examples to geochemical data of natural minerals and rocks and demonstrate that the combination of thermodynamic and geochemical models enables quantification of metamorphic processes and insights into element cycling that would have been unattainable if only one model approach was chosen.

Item Type: Article
Uncontrolled Keywords: thermodynamic–geochemical modeling, fluid–rock interaction, subduction, dehydration, boron isotopes
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 25 May 2015 10:14
Last Modified: 17 May 2019 15:35
URI: https://eprints.keele.ac.uk/id/eprint/545

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