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Thomas Zack - One of the best experts on this subject based on the ideXlab platform.
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petrology and geochronology of Rutile
Reviews in Mineralogy & Geochemistry, 2017Co-Authors: Thomas Zack, Ellen KooijmanAbstract:Rutile (TiO2) is an important accessory mineral that, when present, offers a rich source of information about the rock units in which it is incorporated. It occurs in a variety of specific microstructural settings, contains significant amounts of several trace elements and is one of the classical minerals used for U–Pb age determination. Here, we focus on information obtainable from Rutile in its original textural context. We do not present an exhaustive review on detrital Rutile in clastic sediments, but note that an understanding of the petrochronology of Rutile in its source rocks will aid interpretation of data obtained from detrital Rutile. For further information on the important role of Rutile in provenance studies, the reader is referred to previous reviews (e.g., Zack et al. 2004b; Meinhold 2010; Triebold et al. 2012). Coarse Rutile is the only stable TiO2 polymorph under all crustal and upper mantle conditions, with the exception of certain hydrothermal environments (Smith et al. 2009). As such, we will focus on Rutile rather than the polymorphs brookite, anatase and ultrahigh-pressure modifications. In this chapter, we first review Rutile occurrences, trace element geochemistry, and U–Pb geochronology individually to illustrate the insights that can be gained from microstructures, chemistry and ages. Then, in the spirit of petrochronology, we show the interpretational power of combining these approaches, using the Ivrea Zone (Italy) as a case study. Finally, we suggest some areas of future research that would improve petrochronologic research using Rutile. Rutile is a characteristic mineral in moderate- to high pressure metapelitic rocks, in high pressure metamorphosed mafic rocks, and in sedimentary rocks (e.g., Force 1980; Frost 1991; Zack et al. 2004b; Triebold et al. 2012). Rutile also occurs rarely in magmatic rocks, e.g., anorthosites, as well as in some hydrothermal systems. Coarse-grained …
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Trace element composition of Rutile and Zr-in-Rutile thermometry in meta-ophiolitic rocks from the Kazdağ Massif, NW Turkey
Mineralogy and Petrology, 2016Co-Authors: Fırat Şengün, Thomas ZackAbstract:In northwest Turkey, ophiolitic meta-gabbros are exposed on the Kazdağ Massif located in the southern part of the Biga Peninsula. Trace element composition of Rutile and Zr-in-Rutile temperatures were determined for meta-gabbros from the Kazdağ Massif. The Zr content of all Rutiles range from 176 to 428 ppm and Rutile grains usually have a homogeneous Zr distribution. The Rutile grains from studied samples in the Kazdağ Massif are dominated by subchondritic Nb/Ta (11–19) and Zr/Hf ratios (20–33). Nb/Ta and Zr/Hf show positive correlation, which is probably produced by silicate fractionation. The Nb/Ta and Zr/Hf ratios increase with a decrease in Ta and Hf contents. The core of Rutile grains are generally characterized by low Nb/Ta ratios of 17–18 whereas the rims exhibit relatively high Nb/Ta ratios of 19–23. Trace element analyses in Rutile suggest that these Rutile grains were grown from metamorphic fluids. The P-T conditions of meta-gabbros were estimated by both Fe–Mg exchange and Zr-in-Rutile thermometers, as well as by the Grt-Hb-Plg-Q geothermobarometer. The temperature range of 639 to 662 °C calculated at 9 kbar using the Zr-in-Rutile thermometer is comparable with temperature estimates of the Fe-Mg exchange thermometer, which records amphibolite-facies metamorphism of intermediate P-T conditions. The P-T conditions of meta-ophiolitic rocks suggest that they occur as a different separate higher-pressure tectonic slice in the Kazdağ metamorphic sequence. Amphibolite-facies metamorphism resulted from northward subduction of the İzmir-Ankara branch of the Neo-Tethyan Ocean under the Sakarya Zone. Metamorphism was followed by internal imbrication of the Kazdağ metamorphic sequence resulting from southerly directed compression during the collision.
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Fluid-inclusion microthermometry and the Zr-in-Rutile thermometer for hydrothermal Rutile
International Journal of Earth Sciences, 2015Co-Authors: Alexandre Raphael Cabral, Francisco Javier Rios, Lucilia Aparecida Ramos Oliveira, Francisco Robério Abreu, Bernd Lehmann, Thomas Zack, František LaufekAbstract:The Zr-in-Rutile thermometer is well established for the determination of metamorphic temperatures, particularly in high-grade metamorphic terrains, and for sedimentary provenance studies. The robustness of the Rutile thermometry has not been tested on hydrothermal systems. Unlike quartz, a common hydrothermal mineral with abundant fluid inclusions, it is difficult to find fluid inclusions in Rutile that are suitable for fluid-inclusion microthermometry. Here, we report fluid-inclusion microthermometric measurements in Rutile from the auriferous quartz–kaolinite–hematite vein that typifies the gold deposit of Mil Oitavas in the southern Serra do Espinhaço, Minas Gerais, Brazil. Primary fluid inclusions in the Rutile record moderately saline (10–12 wt% NaCl equivalent), aqueous–carbonic fluids with a total homogenization temperature of ~250 °C, which were likely trapped at about 300 °C and 2.0 kbar. This temperature is approximately 200 °C lower than that predicted by the Zr-in-Rutile thermometer. For hydrothermal conditions of relatively low temperature, direct measurements of homogenization temperatures in Rutile-hosted fluid inclusions should be preferred to the Zr-in-Rutile thermometer.
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A recipe for the use of Rutile in sedimentary provenance analysis
Sedimentary Geology, 2012Co-Authors: Silke Triebold, Hilmar Von Eynatten, Thomas ZackAbstract:Abstract Rutile has received considerable attention in the last decade as a valuable petrogenetic indicator mineral. Based on both new and previously published data, we carve out advantages and pitfalls regarding TiO 2 -minerals in sedimentary provenance analysis. This results in a recipe for the use of Rutile in provenance studies. The main points are: Rutile geochemistry from different grain size fractions does not differ systematically, and hence Rutiles should be extracted from the fraction containing the most Rutile grains (usually 63–200 μm). Similarly, different magnetic susceptibility of Rutile does not systematically imply different trace element composition. Before interpretation of TiO 2 -mineral data, it is important to determine the polymorph type. Rutile, anatase and brookite appear to differ systematically in trace element composition. As an alternative to Raman spectroscopy, chemical classification according to Nb, Cr, Sn, Fe, V, and Zr concentrations can be applied. For Rutile, a new host lithology discrimination scheme based on Cr–Nb systematics is introduced (x = 5 ∗ (Nb [ppm] − 500) − Cr [ppm]), which leads to better classification results than previously published discrimination methods. According to this equation, metamafic Rutiles have negative values of x, while metapelitic Rutiles have positive values. Evaluation of the growth temperature calculations of metamorphic Rutile after different authors shows that the equations given by Tomkins et al. (2007) should be applied to both metamafic and metapelitic Rutiles. Although there is a pressure effect on the Zr incorporation in Rutile, the pressure range for most Rutiles of 5–15 kbar introduces an uncertainty in calculated temperature of no more than ± 35 °C. The distribution of calculated temperatures from detrital Rutiles is crucial; only well-defined temperature populations should be used for thermometry interpretation.
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Discrimination of TiO_2 polymorphs in sedimentary and metamorphic rocks
Contributions to Mineralogy and Petrology, 2011Co-Authors: Silke Triebold, Thomas Zack, George Luiz Luvizotto, Raimon Tolosana-delgado, Hilmar EynattenAbstract:Investigation by Raman spectroscopy of samples from different geological settings shows that the occurrence of TiO_2 polymorphs other than Rutile can hardly be predicted, and furthermore, the occurrence of anatase is more widespread than previously thought. Metamorphic pressure and temperature, together with whole rock chemistry, control the occurrence of anatase, whereas variation of mineral assemblage characteristics and/or fluid occurrence or composition takes influence on anatase trace element characteristics and re-equilibration of relict Rutiles. Evaluation of trace element contents obtained by electron microprobe in anatase, brookite, and Rutile shows that these vary significantly between the three TiO_2 phases. Therefore, on the one hand, an appropriation to source rock type according to Nb and Cr contents, but as well application of thermometry on the basis of Zr contents, would lead to erroneous results if no phase specification is done beforehand. For the elements Cr, V, Fe, and Nb, variation between the polymorphs is systematic and can be used for discrimination on the basis of a linear discriminant analysis. Using phase group means and coefficients of linear discriminants obtained from a compilation of analyses from samples with well-defined phase information together with prior probabilities of groupings from a natural sample compilation, one is able to calculate phase grouping probabilities of any TiO_2 analysis containing at least the critical elements Cr, V, Fe, and Nb. An application of this calculation shows that for the appropriation to the phase Rutile, a correct-classification rate of 99.5% is obtained. Hence, phase specification by trace elements proves to be a valuable tool besides Raman spectroscopy.
Hiroaki Tada - One of the best experts on this subject based on the ideXlab platform.
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TiO2 Crystal Form-Dependence of the Au/TiO2 Plasmon Photocatalyst’s Activity
Journal of Physical Chemistry C, 2012Co-Authors: Keisuke Kimura, Shin-ichi Naya, Yasuaki Jin-nouchi, Hiroaki TadaAbstract:The photocatalytic activities of Au nanoparticle-loaded anatase (Au/anatase) and Rutile (Au/Rutile) for green organic synthesis are compared under illumination of UV and visible light. Whereas Au/anatase shows a higher UV-light activity for the reduction of nitrobenzene than Au/Rutile, the replacement of anatase by Rutile greatly increases the visible-light activity of Au/TiO2 for the oxidation of alcohols to carbonyl compounds. The quantum efficiencies (molecules produced/incident photons) for the Au/Rutile and Au/anatase systems for the selective oxidation of cinnamyl alcohol to cinnamaldehyde were calculated to be 1.4 × 10–3 at λ = 585 ± 15 nm and 0.33 × 10–3 at λ = 555 ± 15 nm, respectively. This superiority of Rutile over anatase as the support of Au nanoparticle (NP) plasmon photocatalyst is also confirmed in the heterosupramolecular system consisting of Au/TiO2 and a cationic surfactant. In the system using Au/Rutile, a quantum efficiency of 6.8 × 10–3 at λ = 585 ± 15 nm has been achieved for the c...
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tio2 crystal form dependence of the au tio2 plasmon photocatalyst s activity
Journal of Physical Chemistry C, 2012Co-Authors: Keisuke Kimura, Shin-ichi Naya, Yasuaki Jinnouchi, Hiroaki TadaAbstract:The photocatalytic activities of Au nanoparticle-loaded anatase (Au/anatase) and Rutile (Au/Rutile) for green organic synthesis are compared under illumination of UV and visible light. Whereas Au/anatase shows a higher UV-light activity for the reduction of nitrobenzene than Au/Rutile, the replacement of anatase by Rutile greatly increases the visible-light activity of Au/TiO2 for the oxidation of alcohols to carbonyl compounds. The quantum efficiencies (molecules produced/incident photons) for the Au/Rutile and Au/anatase systems for the selective oxidation of cinnamyl alcohol to cinnamaldehyde were calculated to be 1.4 × 10–3 at λ = 585 ± 15 nm and 0.33 × 10–3 at λ = 555 ± 15 nm, respectively. This superiority of Rutile over anatase as the support of Au nanoparticle (NP) plasmon photocatalyst is also confirmed in the heterosupramolecular system consisting of Au/TiO2 and a cationic surfactant. In the system using Au/Rutile, a quantum efficiency of 6.8 × 10–3 at λ = 585 ± 15 nm has been achieved for the c...
George Luiz Luvizotto - One of the best experts on this subject based on the ideXlab platform.
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Discrimination of TiO_2 polymorphs in sedimentary and metamorphic rocks
Contributions to Mineralogy and Petrology, 2011Co-Authors: Silke Triebold, Thomas Zack, George Luiz Luvizotto, Raimon Tolosana-delgado, Hilmar EynattenAbstract:Investigation by Raman spectroscopy of samples from different geological settings shows that the occurrence of TiO_2 polymorphs other than Rutile can hardly be predicted, and furthermore, the occurrence of anatase is more widespread than previously thought. Metamorphic pressure and temperature, together with whole rock chemistry, control the occurrence of anatase, whereas variation of mineral assemblage characteristics and/or fluid occurrence or composition takes influence on anatase trace element characteristics and re-equilibration of relict Rutiles. Evaluation of trace element contents obtained by electron microprobe in anatase, brookite, and Rutile shows that these vary significantly between the three TiO_2 phases. Therefore, on the one hand, an appropriation to source rock type according to Nb and Cr contents, but as well application of thermometry on the basis of Zr contents, would lead to erroneous results if no phase specification is done beforehand. For the elements Cr, V, Fe, and Nb, variation between the polymorphs is systematic and can be used for discrimination on the basis of a linear discriminant analysis. Using phase group means and coefficients of linear discriminants obtained from a compilation of analyses from samples with well-defined phase information together with prior probabilities of groupings from a natural sample compilation, one is able to calculate phase grouping probabilities of any TiO_2 analysis containing at least the critical elements Cr, V, Fe, and Nb. An application of this calculation shows that for the appropriation to the phase Rutile, a correct-classification rate of 99.5% is obtained. Hence, phase specification by trace elements proves to be a valuable tool besides Raman spectroscopy.
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Provenance analysis of detrital Rutile: pitfalls and solutions
2010Co-Authors: Silke Triebold, Thomas Zack, Hilmar Von Eynatten, George Luiz Luvizotto, Raimon Tolosana-delgadoAbstract:The growing number of publications dealing with Rutile in sedimentary provenance analysis in the last few years documents the widespread applicability and large potential of this method. Both, Zr-in-Rutile thermometry aspects and lithology discrimination based on Cr and Nb contents have been refined. It is generally thought that Rutile is transformed into other Ti-bearing phases under greenschist facies conditions, and therefore, unlike zircon, Rutile characteristics reflect the last metamorphic event only. However, conclusions from Rutile thermometry in modern and Paleozoic (meta)sediments from the Erzgebirge (Germany) suggest that Rutile may be recycled, and relicts contain information about former metamorphic cycles. Investigation of Rutile samples from different geological settings shows that the occurrence of anatase is more widespread than previously thought and can hardly be predicted. Optical methods and Raman spectroscopy cannot always discern Rutile from its polymorphs. Furthermore, linear discriminant analyses of trace element contents obtained by electron microprobe analysis in Rutile and its polymorphs show that trace element contents in genetically related Rutile, anatase, and brookite exhibit large contrasts indicating that anatase and brookite cannot be used for thermometry or lithology classification purposes substitutional for Rutile. On the other hand, for certain elements (Cr, V, Fe, and Nb) these differences are systematical and can be used for discrimination. On the basis of a calculation applied to each analysis employing prior probabilities for Rutile, anatase, and brookite obtained from a natural sample composition, as well as phase group means and coefficients of linear discriminants from a linear discriminant analysis applied to a well-defined compilation of samples, we obtain correct-classification rates for Rutile of > 0.97. Based on these findings we present a recipe for state-of-the-art Rutile provenance analysis.
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Rutile occurrence and trace element behavior in medium-grade metasedimentary rocks: example from the Erzgebirge, Germany
Mineralogy and Petrology, 2009Co-Authors: George Luiz Luvizotto, Thomas Zack, Silke Triebold, Hilmar EynattenAbstract:Metamorphic textures in medium-grade (~500–550°C) metasedimentary rocks from the Erzgebirge give evidence of prograde Rutile crystallization from ilmenite. Newly-crystallized grains occur as Rutile-rich polycrystalline aggregates that pseudomorph the shape of the ilmenites. In-situ trace element data (EMP and SIMS) show that Rutiles from the higher-grade samples record large scatter in Nb content and have Nb/Ti ratios higher than coexisting ilmenite. This behavior can be predicted using prograde Rutile crystallization from ilmenite and indicates that Rutiles are reequilibrating their chemistry with remaining ilmenites. On the contrary, Rutiles from the lowest grade samples (~480°C) have Nb/Ti ratios that are similar to the ones in ilmenite. Hence, Rutiles from these samples did not equilibrate their chemistry with remaining ilmenites. Our data suggest that temperature may be one of the main factors determining whether or not the elements are able to diffuse between the phases and, therefore, reequilibrate. Newly-crystallized Rutiles yield temperatures (from ~500 to 630°C, Zr-in-Rutile thermometry) that are in agreement with the metamorphic conditions previously determined for the studied rocks. In quartzites from the medium-grade domain (~530°C), inherited detrital Rutile grains are detected. They are identified by their distinct chemical composition (high Zr and Nb contents) and textures (single grains surrounded by fine grained ilmenites). Preliminary calculation, based on grain size distribution of Rutile in medium-grade metapelites and quartzites that occur in the studied area, show that Rutiles derived from quartzites can be anticipated to dominate the detrital Rutile population, even if quartzites are a minor component of the exposure.
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Rutile crystals as potential trace element and isotope mineral standards for microanalysis
Chemical Geology, 2009Co-Authors: George Luiz Luvizotto, Thomas Zack, Silke Triebold, Hanspeter Meyer, Thomas Ludwig, Andreas Kronz, Carsten Munker, Daniel F Stockli, Stefan Prowatke, Stephan KlemmeAbstract:Abstract The present paper reports trace element concentrations of 15 elements (V, Cr, Fe, Zr, Nb, Mo, Sn, Sb, Hf, Ta, W, Lu, Pb, Th and U) as well as Pb and Hf isotope data for four relatively homogeneous and large (centimeter size) Rutile grains. Methods employed are SIMS, EMP, LA-ICP-MS, ID-MC-ICP-MS and TIMS. For most elements homogeneity is usually within ± 10% and occasionally variations are even narrower (± 5%), particularly in the core of two of the studied grains. The trace element concentrations of the grains span a broad compositional range (e.g., Zr concentrations are ca. 4, 100, 300 and 800 ppm). Provisional concentration values, calculated based on the homogeneity of the element and agreement between techniques, are presented for Zr, Nb, Sn, Sb, Hf, Ta, W and U. The present work represents a significant step forward in finding a suitable mineral standard for Rutile microanalysis and encourages not only further search for mineral standards but also applications of Rutile in the field of geochemistry and geochronology. In this sense, the Rutiles presented here are useful as mineral standard in general in-situ Rutile measurements, particularly for Zr-in-Rutile thermometry, quantitative provenance studies (Nb and Cr concentrations as index of source rock type) and U–Pb dating. One of the studied grains has a relatively high U concentration (ca. 30 ppm) and rather constant U–Pb ages (1085.1 to 1096.2 Ma, 207Pb/235U ages and 1086.3 to 1096.6 Ma, 206Pb/238U ages), favoring its application as an age standard for U–Pb Rutile dating. Since Lu concentrations in Rutile are very low and Hf concentrations can be relatively high (tens of ppm), detrital Rutiles may be suitable for obtaining initial Hf isotope composition of source rocks, therefore the Rutiles presented here can be used as calibration material for in-situ Rutile Hf isotope studies.
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nb and zr behavior in Rutile during high grade metamorphism and retrogression an example from the ivrea verbano zone
Chemical Geology, 2009Co-Authors: George Luiz Luvizotto, Thomas ZackAbstract:Abstract Detailed textural observations and in situ analyses (EMP, SIMS and LA-ICP-MS) are used to characterize trace element behavior during prograde and retrograde metamorphic reactions involving Rutile. The Ivrea–Verbano Zone is a classic granulite area and rocks from the Strona and d'Ossola valleys are an example of the amphibolite to granulite facies transition. Although different rock types occur in the area, detailed sampling and petrographic work show that Rutile only occurs in granulite facies paragneisses. These rocks show a rich inventory of textures that allow not only for the investigation of trace element behavior in response to prograde Rutile growth, but also for the effect of post-peak processes on Rutile chemistry. Nb concentrations in Rutile from lower grade samples show a larger spread (from 500 to 5000 ppm within one sample) when compared to those from higher grades. This pattern can be modeled using prograde Rutile growth formed from biotite breakdown. Zr concentrations in Rutile are characterized by an anomalously large spread and a bimodal distribution. Maximum Zr concentrations increase according to the general metamorphic gradient known for this area. Temperatures (from Zr-in-Rutile thermometry), although feasible, are considerably higher than previous calculations (increasing from ca. 850 to 930 °C). A second cluster of Zr concentrations in Rutile occurs at rather constant concentrations (ca. 1000 ppm) for all localities and is interpreted to be related to intense fluid influx at high-temperature and/or to post-peak diffusional resetting favored by slow cooling rates. Alteration textures, characterized by a complex network of micro-veins, are evidence for the late fluid influx. The fluid strongly affected the Rutiles, which is evidenced by corrosion of older Rutile grains and formation of Rutile veinlets.
Silke Triebold - One of the best experts on this subject based on the ideXlab platform.
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A recipe for the use of Rutile in sedimentary provenance analysis
Sedimentary Geology, 2012Co-Authors: Silke Triebold, Hilmar Von Eynatten, Thomas ZackAbstract:Abstract Rutile has received considerable attention in the last decade as a valuable petrogenetic indicator mineral. Based on both new and previously published data, we carve out advantages and pitfalls regarding TiO 2 -minerals in sedimentary provenance analysis. This results in a recipe for the use of Rutile in provenance studies. The main points are: Rutile geochemistry from different grain size fractions does not differ systematically, and hence Rutiles should be extracted from the fraction containing the most Rutile grains (usually 63–200 μm). Similarly, different magnetic susceptibility of Rutile does not systematically imply different trace element composition. Before interpretation of TiO 2 -mineral data, it is important to determine the polymorph type. Rutile, anatase and brookite appear to differ systematically in trace element composition. As an alternative to Raman spectroscopy, chemical classification according to Nb, Cr, Sn, Fe, V, and Zr concentrations can be applied. For Rutile, a new host lithology discrimination scheme based on Cr–Nb systematics is introduced (x = 5 ∗ (Nb [ppm] − 500) − Cr [ppm]), which leads to better classification results than previously published discrimination methods. According to this equation, metamafic Rutiles have negative values of x, while metapelitic Rutiles have positive values. Evaluation of the growth temperature calculations of metamorphic Rutile after different authors shows that the equations given by Tomkins et al. (2007) should be applied to both metamafic and metapelitic Rutiles. Although there is a pressure effect on the Zr incorporation in Rutile, the pressure range for most Rutiles of 5–15 kbar introduces an uncertainty in calculated temperature of no more than ± 35 °C. The distribution of calculated temperatures from detrital Rutiles is crucial; only well-defined temperature populations should be used for thermometry interpretation.
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Discrimination of TiO_2 polymorphs in sedimentary and metamorphic rocks
Contributions to Mineralogy and Petrology, 2011Co-Authors: Silke Triebold, Thomas Zack, George Luiz Luvizotto, Raimon Tolosana-delgado, Hilmar EynattenAbstract:Investigation by Raman spectroscopy of samples from different geological settings shows that the occurrence of TiO_2 polymorphs other than Rutile can hardly be predicted, and furthermore, the occurrence of anatase is more widespread than previously thought. Metamorphic pressure and temperature, together with whole rock chemistry, control the occurrence of anatase, whereas variation of mineral assemblage characteristics and/or fluid occurrence or composition takes influence on anatase trace element characteristics and re-equilibration of relict Rutiles. Evaluation of trace element contents obtained by electron microprobe in anatase, brookite, and Rutile shows that these vary significantly between the three TiO_2 phases. Therefore, on the one hand, an appropriation to source rock type according to Nb and Cr contents, but as well application of thermometry on the basis of Zr contents, would lead to erroneous results if no phase specification is done beforehand. For the elements Cr, V, Fe, and Nb, variation between the polymorphs is systematic and can be used for discrimination on the basis of a linear discriminant analysis. Using phase group means and coefficients of linear discriminants obtained from a compilation of analyses from samples with well-defined phase information together with prior probabilities of groupings from a natural sample compilation, one is able to calculate phase grouping probabilities of any TiO_2 analysis containing at least the critical elements Cr, V, Fe, and Nb. An application of this calculation shows that for the appropriation to the phase Rutile, a correct-classification rate of 99.5% is obtained. Hence, phase specification by trace elements proves to be a valuable tool besides Raman spectroscopy.
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Provenance analysis of detrital Rutile: pitfalls and solutions
2010Co-Authors: Silke Triebold, Thomas Zack, Hilmar Von Eynatten, George Luiz Luvizotto, Raimon Tolosana-delgadoAbstract:The growing number of publications dealing with Rutile in sedimentary provenance analysis in the last few years documents the widespread applicability and large potential of this method. Both, Zr-in-Rutile thermometry aspects and lithology discrimination based on Cr and Nb contents have been refined. It is generally thought that Rutile is transformed into other Ti-bearing phases under greenschist facies conditions, and therefore, unlike zircon, Rutile characteristics reflect the last metamorphic event only. However, conclusions from Rutile thermometry in modern and Paleozoic (meta)sediments from the Erzgebirge (Germany) suggest that Rutile may be recycled, and relicts contain information about former metamorphic cycles. Investigation of Rutile samples from different geological settings shows that the occurrence of anatase is more widespread than previously thought and can hardly be predicted. Optical methods and Raman spectroscopy cannot always discern Rutile from its polymorphs. Furthermore, linear discriminant analyses of trace element contents obtained by electron microprobe analysis in Rutile and its polymorphs show that trace element contents in genetically related Rutile, anatase, and brookite exhibit large contrasts indicating that anatase and brookite cannot be used for thermometry or lithology classification purposes substitutional for Rutile. On the other hand, for certain elements (Cr, V, Fe, and Nb) these differences are systematical and can be used for discrimination. On the basis of a calculation applied to each analysis employing prior probabilities for Rutile, anatase, and brookite obtained from a natural sample composition, as well as phase group means and coefficients of linear discriminants from a linear discriminant analysis applied to a well-defined compilation of samples, we obtain correct-classification rates for Rutile of > 0.97. Based on these findings we present a recipe for state-of-the-art Rutile provenance analysis.
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Rutile occurrence and trace element behavior in medium-grade metasedimentary rocks: example from the Erzgebirge, Germany
Mineralogy and Petrology, 2009Co-Authors: George Luiz Luvizotto, Thomas Zack, Silke Triebold, Hilmar EynattenAbstract:Metamorphic textures in medium-grade (~500–550°C) metasedimentary rocks from the Erzgebirge give evidence of prograde Rutile crystallization from ilmenite. Newly-crystallized grains occur as Rutile-rich polycrystalline aggregates that pseudomorph the shape of the ilmenites. In-situ trace element data (EMP and SIMS) show that Rutiles from the higher-grade samples record large scatter in Nb content and have Nb/Ti ratios higher than coexisting ilmenite. This behavior can be predicted using prograde Rutile crystallization from ilmenite and indicates that Rutiles are reequilibrating their chemistry with remaining ilmenites. On the contrary, Rutiles from the lowest grade samples (~480°C) have Nb/Ti ratios that are similar to the ones in ilmenite. Hence, Rutiles from these samples did not equilibrate their chemistry with remaining ilmenites. Our data suggest that temperature may be one of the main factors determining whether or not the elements are able to diffuse between the phases and, therefore, reequilibrate. Newly-crystallized Rutiles yield temperatures (from ~500 to 630°C, Zr-in-Rutile thermometry) that are in agreement with the metamorphic conditions previously determined for the studied rocks. In quartzites from the medium-grade domain (~530°C), inherited detrital Rutile grains are detected. They are identified by their distinct chemical composition (high Zr and Nb contents) and textures (single grains surrounded by fine grained ilmenites). Preliminary calculation, based on grain size distribution of Rutile in medium-grade metapelites and quartzites that occur in the studied area, show that Rutiles derived from quartzites can be anticipated to dominate the detrital Rutile population, even if quartzites are a minor component of the exposure.
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Rutile crystals as potential trace element and isotope mineral standards for microanalysis
Chemical Geology, 2009Co-Authors: George Luiz Luvizotto, Thomas Zack, Silke Triebold, Hanspeter Meyer, Thomas Ludwig, Andreas Kronz, Carsten Munker, Daniel F Stockli, Stefan Prowatke, Stephan KlemmeAbstract:Abstract The present paper reports trace element concentrations of 15 elements (V, Cr, Fe, Zr, Nb, Mo, Sn, Sb, Hf, Ta, W, Lu, Pb, Th and U) as well as Pb and Hf isotope data for four relatively homogeneous and large (centimeter size) Rutile grains. Methods employed are SIMS, EMP, LA-ICP-MS, ID-MC-ICP-MS and TIMS. For most elements homogeneity is usually within ± 10% and occasionally variations are even narrower (± 5%), particularly in the core of two of the studied grains. The trace element concentrations of the grains span a broad compositional range (e.g., Zr concentrations are ca. 4, 100, 300 and 800 ppm). Provisional concentration values, calculated based on the homogeneity of the element and agreement between techniques, are presented for Zr, Nb, Sn, Sb, Hf, Ta, W and U. The present work represents a significant step forward in finding a suitable mineral standard for Rutile microanalysis and encourages not only further search for mineral standards but also applications of Rutile in the field of geochemistry and geochronology. In this sense, the Rutiles presented here are useful as mineral standard in general in-situ Rutile measurements, particularly for Zr-in-Rutile thermometry, quantitative provenance studies (Nb and Cr concentrations as index of source rock type) and U–Pb dating. One of the studied grains has a relatively high U concentration (ca. 30 ppm) and rather constant U–Pb ages (1085.1 to 1096.2 Ma, 207Pb/235U ages and 1086.3 to 1096.6 Ma, 206Pb/238U ages), favoring its application as an age standard for U–Pb Rutile dating. Since Lu concentrations in Rutile are very low and Hf concentrations can be relatively high (tens of ppm), detrital Rutiles may be suitable for obtaining initial Hf isotope composition of source rocks, therefore the Rutiles presented here can be used as calibration material for in-situ Rutile Hf isotope studies.
Andreas Kronz - One of the best experts on this subject based on the ideXlab platform.
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Rutile crystals as potential trace element and isotope mineral standards for microanalysis
Chemical Geology, 2009Co-Authors: George Luiz Luvizotto, Thomas Zack, Silke Triebold, Hanspeter Meyer, Thomas Ludwig, Andreas Kronz, Carsten Munker, Daniel F Stockli, Stefan Prowatke, Stephan KlemmeAbstract:Abstract The present paper reports trace element concentrations of 15 elements (V, Cr, Fe, Zr, Nb, Mo, Sn, Sb, Hf, Ta, W, Lu, Pb, Th and U) as well as Pb and Hf isotope data for four relatively homogeneous and large (centimeter size) Rutile grains. Methods employed are SIMS, EMP, LA-ICP-MS, ID-MC-ICP-MS and TIMS. For most elements homogeneity is usually within ± 10% and occasionally variations are even narrower (± 5%), particularly in the core of two of the studied grains. The trace element concentrations of the grains span a broad compositional range (e.g., Zr concentrations are ca. 4, 100, 300 and 800 ppm). Provisional concentration values, calculated based on the homogeneity of the element and agreement between techniques, are presented for Zr, Nb, Sn, Sb, Hf, Ta, W and U. The present work represents a significant step forward in finding a suitable mineral standard for Rutile microanalysis and encourages not only further search for mineral standards but also applications of Rutile in the field of geochemistry and geochronology. In this sense, the Rutiles presented here are useful as mineral standard in general in-situ Rutile measurements, particularly for Zr-in-Rutile thermometry, quantitative provenance studies (Nb and Cr concentrations as index of source rock type) and U–Pb dating. One of the studied grains has a relatively high U concentration (ca. 30 ppm) and rather constant U–Pb ages (1085.1 to 1096.2 Ma, 207Pb/235U ages and 1086.3 to 1096.6 Ma, 206Pb/238U ages), favoring its application as an age standard for U–Pb Rutile dating. Since Lu concentrations in Rutile are very low and Hf concentrations can be relatively high (tens of ppm), detrital Rutiles may be suitable for obtaining initial Hf isotope composition of source rocks, therefore the Rutiles presented here can be used as calibration material for in-situ Rutile Hf isotope studies.
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Temperature dependence of Zr in Rutile: empirical calibration of a Rutile thermometer
Contributions to Mineralogy and Petrology, 2004Co-Authors: Thomas Zack, Renato De Moraes, Andreas KronzAbstract:Rutile is an important carrier of high field strength elements (HFSE; Zr, Nb, Mo, Sn, Sb, Hf, Ta, W). Its Zr content is buffered in systems with quartz and zircon as coexisting phases. The effects of temperature (T) and pressure (P) on the Zr content in Rutile have been empirically calibrated in this study by analysing Rutile–quartz–zircon assemblages of 31 metamorphic rocks spanning a T range from 430 to 1,100°C. Electron microprobe measurements show that Zr concentrations in Rutile vary from 30 to 8,400 ppm across this temperature interval, correlating closely with metamorphic grade. The following thermometer has been formulated based on the maximum Zr contents of Rutile included in garnet and pyroxene: $$ T{\text{(in}}\;^ \circ {\text{C) = 127}}{\text{.8}}\, \times {\text{ln (Zr}}\,{\text{in}}\,{\text{ppm)}}\, - {\text{10}} $$ No pressure dependence was observed. An uncertainty in absolute T of ±50°C is inherited from T estimates of the natural samples used. A close approach to equilibrium of Zr distribution between zircon and Rutile is suggested based on the high degree of reproducability of Zr contents in Rutiles from different rock types from the same locality. At a given locality, the calculated range in T is mostly ±10°C, indicating the geological and analytical precision of the Rutile thermometer. Possible applications of this new geothermometer are discussed covering the fields of ultrahigh temperature (UHT) granulites, sedimentary provenance studies and metamorphic field gradients.
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trace element abundances in Rutiles from eclogites and associated garnet mica schists
Chemical Geology, 2002Co-Authors: Thomas Zack, Andreas Kronz, Stephen F Foley, Toby RiversAbstract:Abstract We present electron microprobe and laser ablation microprobe (LAM) data for a range of high field strength (Zr, Nb, Mo, Sn, Sb, Hf, Ta, W) and other trace elements (Al, Si, Ca, V, Cr, Mn, Fe, Pb, Th, U) in Rutile from eclogites and garnet mica schists from Trescolmen, Central Alps. Most analysed Rutiles are homogeneous (at least for Nb, Cr, W, Zr, V and Fe), both on a single grain scale and between grains from a single thin section. Concentrations of V, Zr, Nb, Sb and W determined by both electron and laser ablation microprobe techniques yield similar results and confirm the reliability of the analytical methods within estimated precision. Measurements of trace element contents of coexisting phases in eclogites and their modal abundances show that Rutile is the dominant carrier (>90% of whole rock content) for Ti, Nb, Sb, Ta and W as well as an important carrier (5–45% of the whole rock content) for V, Cr, Mo and Sn. The crystallographic implications are that, for relatively rigid crystal sites such as in Rutile, trace elements with a similar ionic radius are preferred over trace elements with the same charge but deviating size. Our results demonstrate the utility of Rutile chemistry in the following applications: (1) By using a combination of the measured TiO2 content of the whole rock and the trace element concentration of Rutile, precise whole rock data on elements that are either difficult to analyze by conventional techniques such as XRF or solution ICP-MS (Nb, Sb, Ta, W) or may be susceptible to late stage alteration (Sb) can be estimated. (2) Trace element contents of detrital Rutile grains are a potentially powerful tool for sedimentary provenance studies since they reflect key element ratios (e.g., Nb/TiO2 and Cr/TiO2) of their source rocks. In addition, measurements of trace elements in detrital Rutiles might help distinguish possible source rocks, e.g., high-grade metamorphic rocks such as eclogites and high-pressure granulites from hydrothermal ore deposits and kimberlites. In view of the dominance of Rutile in the Sb budget of subducting oceanic crust, and the enrichment of Sb in the slab component of subduction zones, additional experimental studies on Sb-partitioning between Rutile and fluid are needed in order to understand the behaviour of Sb in subduction zones.
