Hydrogen in spessartine-almandine garnets as a tracer of granitic pegmatite evolution

Arredondo, Elizabeth H.; Rossman, George R.; Lumpkin, Gregory R.

doi:10.2138/am-2001-0412

Cited by 33 publications

(20 citation statements)

References 5 publications

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“…Spess has more peaks (nine defined) than the other garnets. The spectrum is similar to that presented by Aines and Rossman (1984a) and Arredondo et al (2001); spessartine (4) from Rutherford pegmatites (Virginia). Spess has the same triplet, ~ 3614-3626-3639 cm − 1 and main doublet ~ 3583-3595 cm − 1 , but the low wavenumber peaks, ~ 3484-3514-3533-3562 cm − 1 , are not present in the spectra of Rutherford garnets.…”

Section: Ftir Absorption Bandssupporting

confidence: 83%

Experimental constraints on hydrogen diffusion in garnet

Reynes

Jollands

Hermann

et al. 2018

Contrib Mineral Petrol

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The incorporation mechanisms and diffusional loss of hydrogen in garnet have been experimentally investigated. A suite of gem-quality hydrous spessartine-and grossular-rich garnets were analysed by Fourier transform infrared spectroscopy (FTIR) and by ion microprobe (SHRIMP-SI) to determine the calibration coefficients for quantification of FTIR data. The excellent agreement between measured absorption and OH/O indicates that the same molar extinction coefficient can be used for spessartine and grossular. The coefficient of 14400 l mol − 1 cm − 2 proposed by Maldener et al. (Phys Chem Miner 30:337-344, 2003) seems the most appropriate for both minerals. A grossular with 6.4% andradite and 1.6% almandine containing 834 ppm H 2 O, and an almost pure spessartine with 282 ppm H 2 O, were selected for diffusion experiments. 1.5-mm cubes of garnets were heated between 12 h and 10 days at 1 atm under various temperature (750-1050 °C) and oxygen fugacity ( f O 2 ) conditions, (ΔQFM + 15.2 to − 3.0). Diffusion profiles were acquired from sections through the cubes using FTIR, with a deconvolution algorithm developed to assess peak-specific behaviour. Different families of peaks have been identified based on their diffusive behaviour, representing hydrogen incorporated in different H-bearing defects. A dominant, fast, strongly f O 2 -dependent oxidation-related diffusion mechanism is proposed) with a relatively low activation energy (158 ± 19 kJ mol − 1 ). This diffusion mechanism is likely restricted by availability of ferrous iron in grossular. At low oxygen fugacity, this diffusion mechanism is shut off and the diffusivity decreased by more than three orders of magnitude. A second, slower hydrogen diffusion mechanism has been observed in minor bands, where charge balance might be maintained by diffusion of cation vacancies, with much higher activation energy (≈ 200-270 kJ mol − 1 ). Spessartine shows clear differences in peak retentivity suggesting that up to four different H sites might exist. This opens exciting opportunities to use hydrogen diffusion in garnet as speedometer. However, it is essential to constrain the main diffusion mechanisms and the oxygen fugacity in the rocks investigated to obtain timescales for metamorphic or igneous processes.

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Section: Ftir Absorption Bandssupporting

confidence: 83%

Experimental constraints on hydrogen diffusion in garnet

Reynes

Jollands

Hermann

et al. 2018

Contrib Mineral Petrol

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“…Garnet dominated by ugrandite endmembers can 54 incorporate up to several wt.% H2O (Rossman and Aines 1991), whereas pyralspite garnets usually 55 incorporate only a few hundreds of ppm (Aines and Rossman 1984a). Spessartine can incorporate 56 more water (up to 1000 ppm H2O, Arredondo et al 2001) than pyrope and almandine (< 150 ppm 57 H2O). Because garnet has these various solid solutions and their affinity for H2O seems to differ, a 58 correlation between major elements and OH groups at a comparable scale is needed.…”

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confidence: 99%

A mapping approach for the investigation of Ti–OH relationships in metamorphic garnet

Reynes

Lanari

Hermann

2020

Contrib Mineral Petrol

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Garnet is a nominally anhydrous mineral that can incorporate several hundreds of ppm H2O in the 8 form of OH groups, where H + substitutes for cations in the garnet structure. In order to understand the 9 ManuscriptClick here to access/download;Manuscript;Manuscript_review2_Reynesetal Click here to view linked References Keywords: Quantitative compositional mapping -Garnet -FTIR mapping -Nominally anhydrous 31 minerals 32 33 Introduction 34Garnet is a common metamorphic mineral formed during prograde dehydration reactions such as 35 encountered during the subduction of oceanic crust and sediments. The garnet formula contains 36 neither H2O nor OH groups, nevertheless it can incorporate several hundreds of ppm H2O as OH 37 groups where H + incorporation is charge-balanced by cation substitutions. Because of the large P-T 38 stability field of garnet, the incorporated H2O can be transported inside the slab to the deep mantle and 39 might play an important role in the Earth's deep water cycle. It is essential to know where the OH 40 groups are located in the garnet structure, and which coupled substitutions exist for the incorporation 41 of H + . The dominant substitution found so far is the replacement of a Si 4+ cation by 4H + , known as the 42 hydrogarnet point defect (Cohen-Addad et al. 1967;Foreman 1968;Lager et al. 1987). Other point 43 defects have been proposed, involving H + substitutions for dodecahedral and octahedral cations 44 Andrut et al. 2002;Basso et al. 1984;Geiger et al. 1991). Coupled substitutions have been invoked 45 such as H-B and H-Li point defects (Lu and Keppler 1997) and even incomplete silicon vacancies, 46 like 3H + substituting for a Si 4+ and being compensated by Ti 4+ in octahedral site (Khomenko et al. 47 1994), or Fe 3+ or Fe 2+ together with one of two H + in the tetrahedral site in Ti-rich garnets (Kühberger 48 et al. 1989). Recent studies support that multiple point defects are present in single garnet grains 49 (Geiger and Rossman 2018;Reynes, et al. 2018). It has been shown that garnet composition does 50 influence the incorporation of OH groups in the garnet structure. Garnet is a complex solid solution 51 involving various endmembers. Spessartine (Mn-Al), almandine (Fe 2+ -Al), pyrope (Mg-Al) constitute 52 the widespread pyralspite subfamily, whereas grossular (Ca-Al), andradite (Ca-Fe 3+ ) and uvarovite 53 (Ca-Cr 3+ ) belong to the ugrandite subfamily. Garnet dominated by ugrandite endmembers can 54 incorporate up to several wt.% H2O (Rossman and Aines 1991), whereas pyralspite garnets usually 55 incorporate only a few hundreds of ppm (Aines and Rossman 1984a). Spessartine can incorporate 56 more water (up to 1000 ppm H2O, Arredondo et al. 2001) than pyrope and almandine (< 150 ppm 57 H2O). Because garnet has these various solid solutions and their affinity for H2O seems to differ, a 58 correlation between major elements and OH groups at a comparable scale is needed. Major and minor 59 element chemistry of garnet is usually measured by Electron Probe Micro-Analysis (E...

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“…Figure 3 shows a signiÞ cant band at 5195 cm -1 and a weaker mode at 5380 cm -1 in tourmaline sample LC1. Bands at about 5200 cm -1 result from the combination of stretching and bending modes of molecular water (e.g., Arredondo et al 2001). Because it is not clear if H 2 O is present as ß uid inclusions or as a part of the structure, particular care was taken in the spectroscopic experiments to distinguish between the two possibilities.…”

Section: Oh and H 2 Omentioning

confidence: 99%

Introduction and Previous Work

Ibrahim

Dessouky

Attia

et al. 2022

Green Energy and Technology

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was published, studies had "not provided compelling evidence" for IV B (Henry and Dutrow 1996, p. 504). Of great signiÞ cance are the implications for understanding why some tourmalines incorporate IV B and others do not. In this work, we provide detailed models with short-range orders to explain the relationship between the occupancy at the Y site and the T site.These short-range orders imply also that an oft-used calculation of the Li content by difference on the Y site may be problematic for Al-rich tourmalines (olenite, elbaite, rossmanite) because these tourmalines can contain vacancies at this site. It can also be problematic to normalize such tourmalines to 6.00 Si apfu by ignoring B non-stoichimetry, especially when they contain only low amounts of Fe, Mn, and the Al content at the Y site exceeds 1.3 apfu.Tourmalines that contain IV B were described recently from several localities. From a pegmatite near Stoffhütte, Koralpe, Styria, Austria, olenite samples with up to ~1 apfu IV B were described (

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Hydrogen in spessartine-almandine garnets as a tracer of granitic pegmatite evolution

Cited by 33 publications

References 5 publications

Experimental constraints on hydrogen diffusion in garnet

Experimental constraints on hydrogen diffusion in garnet

A mapping approach for the investigation of Ti–OH relationships in metamorphic garnet

Introduction and Previous Work

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