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Ralf Halama - One of the best experts on this subject based on the ideXlab platform.
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Boron isotope record of peak metamorphic ultrahigh-pressure and retrograde fluid–rock Interaction in white mica (Lago di Cignana, Western Alps)
Contributions to Mineralogy and Petrology, 2020Co-Authors: Ralf Halama, Matthias Konrad-schmolke, Jan C. M. HoogAbstract:This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track fluid–rock Interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet–phengite quartzite. The B isotopic composition is variable (δ^11B = − 10.3 to − 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differences, prograde growth zoning, diffusion nor a retrograde overprint can explain this correlation. Modelling shows that B devolatilization during metamorphism can explain the general trend, but fails to account for the wide compositional and isotopic variability in a single, well-equilibrated sample. We, therefore, argue that this trend represents fluid–rock Interaction during peak metamorphic conditions. This interpretation is supported by fluid–rock Interaction modelling of boron leaching and boron addition that can successfully reproduce the observed spread in δ^11B and [B]. Taking into account the local availability of serpentinites as potential source rocks of the fluids, the temperatures reached during peak metamorphism that allow for serpentine dehydration, and the high positive δ^11B values (δ^11B = 20 ± 5) modelled for the fluids, an influx of serpentinite-derived fluid appears likely. Paragonite in lawsonite pseudomorphs in an eclogite and phengite from a retrogressed metabasite have B contents between 12 and 68 μg/g and δ^11B values that cluster around 0% (δ^11B = − 5.0 to + 3.5). White mica in both samples is related to distinct stages of retrograde metamorphism during exhumation of the rocks. The variable B geochemistry can be successfully modelled as fluid–rock Interaction with low-to-moderate (
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boron isotope record of peak metamorphic ultrahigh pressure and retrograde fluid rock Interaction in white mica lago di cignana western alps
Contributions to Mineralogy and Petrology, 2020Co-Authors: Ralf Halama, Matthias Konradschmolke, Jan C. M. HoogAbstract:: This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track Fluid-Rock Interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet-phengite quartzite. The B isotopic composition is variable (δ11B = - 10.3 to - 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differences, prograde growth zoning, diffusion nor a retrograde overprint can explain this correlation. Modelling shows that B devolatilization during metamorphism can explain the general trend, but fails to account for the wide compositional and isotopic variability in a single, well-equilibrated sample. We, therefore, argue that this trend represents Fluid-Rock Interaction during peak metamorphic conditions. This interpretation is supported by Fluid-Rock Interaction modelling of boron leaching and boron addition that can successfully reproduce the observed spread in δ11B and [B]. Taking into account the local availability of serpentinites as potential source rocks of the fluids, the temperatures reached during peak metamorphism that allow for serpentine dehydration, and the high positive δ11B values (δ11B = 20 ± 5) modelled for the fluids, an influx of serpentinite-derived fluid appears likely. Paragonite in lawsonite pseudomorphs in an eclogite and phengite from a retrogressed metabasite have B contents between 12 and 68 μg/g and δ11B values that cluster around 0% (δ11B = - 5.0 to + 3.5). White mica in both samples is related to distinct stages of retrograde metamorphism during exhumation of the rocks. The variable B geochemistry can be successfully modelled as Fluid-Rock Interaction with low-to-moderate (< 3) fluid/rock ratios, where mica equilibrates with a fluid into which B preferentially partitions, causing leaching of B from the rock. The metamorphic rocks from Lago di Cignana show variable retention of B in white mica during subduction-related metamorphism and exhumation. The variability in the B geochemical signature in white mica is significant and enhances our understanding of metamorphic processes and their role in element transfer in subduction zones.
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Fluid-induced breakdown of white mica controls nitrogen transfer during fluid–rock Interaction in subduction zones
International Geology Review, 2016Co-Authors: Ralf Halama, Gray E. Bebout, Horst R. Marschall, Timm JohnAbstract:ABSTRACTIn order to determine the effects of fluid–rock Interaction on nitrogen elemental and isotopic systematics in high-pressure metamorphic rocks, we investigated three different profiles representing three distinct scenarios of metasomatic overprinting. A profile from the Chinese Tianshan (ultra)high-pressure–low-temperature metamorphic belt represents a prograde, fluid-induced blueschist–eclogite transformation. This profile shows a systematic decrease in N concentrations from the host blueschist (~26 μg/g) via a blueschist–eclogite transition zone (19–23 μg/g) and an eclogitic selvage (12–16 μg/g) towards the former fluid pathway. Eclogites and blueschists show only a small variation in δ15Nair (+2.1 ± 0.3‰), but the systematic trend with distance is consistent with a batch devolatilization process. A second profile from the Tianshan represents a retrograde eclogite–blueschist transition. It shows increasing, but more scattered, N concentrations from the eclogite towards the blueschist and an unsys...
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combined thermodynamic geochemical modeling in metamorphic geology boron as tracer of fluid rock Interaction
Lithos, 2014Co-Authors: Matthias Konradschmolke, Ralf HalamaAbstract:Abstract 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.
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Combined thermodynamic–geochemical modeling in metamorphic geology: Boron as tracer of fluid–rock Interaction
Lithos, 2014Co-Authors: Matthias Konrad-schmolke, Ralf HalamaAbstract:Abstract 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.
Yaohui Jiang - One of the best experts on this subject based on the ideXlab platform.
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fluid rock Interaction in the qitianling granite and associated tin deposits south china evidence from boron and oxygen isotopes
Ore Geology Reviews, 2011Co-Authors: Shaoyong Jiang, Kuidong Zhao, Eizo Nakamura, Takuya Moriguti, Martin R Palmer, Shuiyuan Yang, Bao Zhang Dai, Yaohui JiangAbstract:article i nfo Article history: The behavior of boron and its isotopes in fluid-dominant processes and hydrothermal alteration of granites is examined using fresh and altered granite samples from the Qitianling granite and associated hydrothermal tin deposits in South China. Boron concentrations are highest in the fresh granite (37 ppm) and depleted as a result of two stages of fluid mobility and Fluid-Rock Interaction within the granite. Constraints provided both by δ 11 B and δ 18 O data suggest that the first stage was related to exsolution of aqueous fluids from the granite magma at a temperature of N450 °C. This was followed by further boron depletion in the granite by hydrothermal circulation of meteoric water at lower temperatures (~350 °C) and low water/rock ratios. The sensitivity of coupled boron and oxygen isotope systematics to these processes suggests that they can provide valuable constraints on of fluid mobility in granite and associated mineralization.
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Fluid–rock Interaction in the Qitianling granite and associated tin deposits, South China: Evidence from boron and oxygen isotopes
Ore Geology Reviews, 2011Co-Authors: Kuidong Zhao, Shaoyong Jiang, Eizo Nakamura, Takuya Moriguti, Martin R Palmer, Shuiyuan Yang, Bao Zhang Dai, Yaohui JiangAbstract:article i nfo Article history: The behavior of boron and its isotopes in fluid-dominant processes and hydrothermal alteration of granites is examined using fresh and altered granite samples from the Qitianling granite and associated hydrothermal tin deposits in South China. Boron concentrations are highest in the fresh granite (37 ppm) and depleted as a result of two stages of fluid mobility and Fluid-Rock Interaction within the granite. Constraints provided both by δ 11 B and δ 18 O data suggest that the first stage was related to exsolution of aqueous fluids from the granite magma at a temperature of N450 °C. This was followed by further boron depletion in the granite by hydrothermal circulation of meteoric water at lower temperatures (~350 °C) and low water/rock ratios. The sensitivity of coupled boron and oxygen isotope systematics to these processes suggests that they can provide valuable constraints on of fluid mobility in granite and associated mineralization.
Kuidong Zhao - One of the best experts on this subject based on the ideXlab platform.
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fluid rock Interaction in the qitianling granite and associated tin deposits south china evidence from boron and oxygen isotopes
Ore Geology Reviews, 2011Co-Authors: Shaoyong Jiang, Kuidong Zhao, Eizo Nakamura, Takuya Moriguti, Martin R Palmer, Shuiyuan Yang, Bao Zhang Dai, Yaohui JiangAbstract:article i nfo Article history: The behavior of boron and its isotopes in fluid-dominant processes and hydrothermal alteration of granites is examined using fresh and altered granite samples from the Qitianling granite and associated hydrothermal tin deposits in South China. Boron concentrations are highest in the fresh granite (37 ppm) and depleted as a result of two stages of fluid mobility and Fluid-Rock Interaction within the granite. Constraints provided both by δ 11 B and δ 18 O data suggest that the first stage was related to exsolution of aqueous fluids from the granite magma at a temperature of N450 °C. This was followed by further boron depletion in the granite by hydrothermal circulation of meteoric water at lower temperatures (~350 °C) and low water/rock ratios. The sensitivity of coupled boron and oxygen isotope systematics to these processes suggests that they can provide valuable constraints on of fluid mobility in granite and associated mineralization.
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Fluid–rock Interaction in the Qitianling granite and associated tin deposits, South China: Evidence from boron and oxygen isotopes
Ore Geology Reviews, 2011Co-Authors: Kuidong Zhao, Shaoyong Jiang, Eizo Nakamura, Takuya Moriguti, Martin R Palmer, Shuiyuan Yang, Bao Zhang Dai, Yaohui JiangAbstract:article i nfo Article history: The behavior of boron and its isotopes in fluid-dominant processes and hydrothermal alteration of granites is examined using fresh and altered granite samples from the Qitianling granite and associated hydrothermal tin deposits in South China. Boron concentrations are highest in the fresh granite (37 ppm) and depleted as a result of two stages of fluid mobility and Fluid-Rock Interaction within the granite. Constraints provided both by δ 11 B and δ 18 O data suggest that the first stage was related to exsolution of aqueous fluids from the granite magma at a temperature of N450 °C. This was followed by further boron depletion in the granite by hydrothermal circulation of meteoric water at lower temperatures (~350 °C) and low water/rock ratios. The sensitivity of coupled boron and oxygen isotope systematics to these processes suggests that they can provide valuable constraints on of fluid mobility in granite and associated mineralization.
Matthias Konrad-schmolke - One of the best experts on this subject based on the ideXlab platform.
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Boron isotope record of peak metamorphic ultrahigh-pressure and retrograde fluid–rock Interaction in white mica (Lago di Cignana, Western Alps)
Contributions to Mineralogy and Petrology, 2020Co-Authors: Ralf Halama, Matthias Konrad-schmolke, Jan C. M. HoogAbstract:This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track fluid–rock Interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet–phengite quartzite. The B isotopic composition is variable (δ^11B = − 10.3 to − 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differences, prograde growth zoning, diffusion nor a retrograde overprint can explain this correlation. Modelling shows that B devolatilization during metamorphism can explain the general trend, but fails to account for the wide compositional and isotopic variability in a single, well-equilibrated sample. We, therefore, argue that this trend represents fluid–rock Interaction during peak metamorphic conditions. This interpretation is supported by fluid–rock Interaction modelling of boron leaching and boron addition that can successfully reproduce the observed spread in δ^11B and [B]. Taking into account the local availability of serpentinites as potential source rocks of the fluids, the temperatures reached during peak metamorphism that allow for serpentine dehydration, and the high positive δ^11B values (δ^11B = 20 ± 5) modelled for the fluids, an influx of serpentinite-derived fluid appears likely. Paragonite in lawsonite pseudomorphs in an eclogite and phengite from a retrogressed metabasite have B contents between 12 and 68 μg/g and δ^11B values that cluster around 0% (δ^11B = − 5.0 to + 3.5). White mica in both samples is related to distinct stages of retrograde metamorphism during exhumation of the rocks. The variable B geochemistry can be successfully modelled as fluid–rock Interaction with low-to-moderate (
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Combined thermodynamic–geochemical modeling in metamorphic geology: Boron as tracer of fluid–rock Interaction
Lithos, 2014Co-Authors: Matthias Konrad-schmolke, Ralf HalamaAbstract:Abstract 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.
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Fluid migration above a subducted slab — Thermodynamic and trace element modelling of fluid–rock Interaction in partially overprinted eclogite-facies rocks (Sesia Zone, Western Alps)
Earth and Planetary Science Letters, 2011Co-Authors: Matthias Konrad-schmolke, Thomas Zack, Patrick J. O'brien, Matthias BarthAbstract:Abstract The amount and composition of subduction zone fluids and the effect of fluid–rock Interaction at a slab–mantle interface have been constrained by thermodynamic and trace element modelling of partially overprinted blueschist-facies rocks from the Sesia Zone (Western Alps). Deformation-induced differences in fluid flux led to a partial preservation of pristine mineral cores in weakly deformed samples that were used to quantify Li, B, Sr and Pb distribution during mineral growth, -breakdown and modification induced by fluid–rock Interaction. Our results show that Li and B budgets are fluid-controlled, thus acting as tracers for fluid–rock Interaction processes, whereas Sr and Pb budgets are mainly controlled by the fluid-induced formation of epidote. Our calculations show that fluid–rock Interaction caused significant Li and B depletion in the affected rocks due to leaching effects, which in turn can lead to a drastic enrichment of these elements in the percolating fluid. Depending on available fluid-mineral trace element distribution coefficients modelled fluid rock ratios were up to 0.06 in weakly deformed samples and at least 0.5 to 4 in shear zone mylonites. These amounts lead to time integrated fluid fluxes of up to 1.4 ∙ 10 2 m 3 m − 2 in the weakly deformed rocks and 1–8 ∙ 10 3 m 3 m − 2 in the mylonites. Combined thermodynamic and trace element models can be used to quantify metamorphic fluid fluxes and the associated element transfer in complex, reacting rock systems and help to better understand commonly observed fluid-induced trace element trends in rocks and minerals from different geodynamic environments.
Jan C. M. Hoog - One of the best experts on this subject based on the ideXlab platform.
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Boron isotope record of peak metamorphic ultrahigh-pressure and retrograde fluid–rock Interaction in white mica (Lago di Cignana, Western Alps)
Contributions to Mineralogy and Petrology, 2020Co-Authors: Ralf Halama, Matthias Konrad-schmolke, Jan C. M. HoogAbstract:This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track fluid–rock Interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet–phengite quartzite. The B isotopic composition is variable (δ^11B = − 10.3 to − 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differences, prograde growth zoning, diffusion nor a retrograde overprint can explain this correlation. Modelling shows that B devolatilization during metamorphism can explain the general trend, but fails to account for the wide compositional and isotopic variability in a single, well-equilibrated sample. We, therefore, argue that this trend represents fluid–rock Interaction during peak metamorphic conditions. This interpretation is supported by fluid–rock Interaction modelling of boron leaching and boron addition that can successfully reproduce the observed spread in δ^11B and [B]. Taking into account the local availability of serpentinites as potential source rocks of the fluids, the temperatures reached during peak metamorphism that allow for serpentine dehydration, and the high positive δ^11B values (δ^11B = 20 ± 5) modelled for the fluids, an influx of serpentinite-derived fluid appears likely. Paragonite in lawsonite pseudomorphs in an eclogite and phengite from a retrogressed metabasite have B contents between 12 and 68 μg/g and δ^11B values that cluster around 0% (δ^11B = − 5.0 to + 3.5). White mica in both samples is related to distinct stages of retrograde metamorphism during exhumation of the rocks. The variable B geochemistry can be successfully modelled as fluid–rock Interaction with low-to-moderate (
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boron isotope record of peak metamorphic ultrahigh pressure and retrograde fluid rock Interaction in white mica lago di cignana western alps
Contributions to Mineralogy and Petrology, 2020Co-Authors: Ralf Halama, Matthias Konradschmolke, Jan C. M. HoogAbstract:: This study presents boron (B) concentration and isotope data for white mica from (ultra)high-pressure (UHP), subduction-related metamorphic rocks from Lago di Cignana (Western Alps, Italy). These rocks are of specific geological interest, because they comprise the most deeply subducted rocks of oceanic origin worldwide. Boron geochemistry can track Fluid-Rock Interaction during their metamorphic evolution and provide important insights into mass transfer processes in subduction zones. The highest B contents (up to 345 μg/g B) occur in peak metamorphic phengite from a garnet-phengite quartzite. The B isotopic composition is variable (δ11B = - 10.3 to - 3.6%) and correlates positively with B concentrations. Based on similar textures and major element mica composition, neither textural differences, prograde growth zoning, diffusion nor a retrograde overprint can explain this correlation. Modelling shows that B devolatilization during metamorphism can explain the general trend, but fails to account for the wide compositional and isotopic variability in a single, well-equilibrated sample. We, therefore, argue that this trend represents Fluid-Rock Interaction during peak metamorphic conditions. This interpretation is supported by Fluid-Rock Interaction modelling of boron leaching and boron addition that can successfully reproduce the observed spread in δ11B and [B]. Taking into account the local availability of serpentinites as potential source rocks of the fluids, the temperatures reached during peak metamorphism that allow for serpentine dehydration, and the high positive δ11B values (δ11B = 20 ± 5) modelled for the fluids, an influx of serpentinite-derived fluid appears likely. Paragonite in lawsonite pseudomorphs in an eclogite and phengite from a retrogressed metabasite have B contents between 12 and 68 μg/g and δ11B values that cluster around 0% (δ11B = - 5.0 to + 3.5). White mica in both samples is related to distinct stages of retrograde metamorphism during exhumation of the rocks. The variable B geochemistry can be successfully modelled as Fluid-Rock Interaction with low-to-moderate (< 3) fluid/rock ratios, where mica equilibrates with a fluid into which B preferentially partitions, causing leaching of B from the rock. The metamorphic rocks from Lago di Cignana show variable retention of B in white mica during subduction-related metamorphism and exhumation. The variability in the B geochemical signature in white mica is significant and enhances our understanding of metamorphic processes and their role in element transfer in subduction zones.