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  • 1
    Electronic Resource
    Electronic Resource
    Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer (1990)
    Springer
    Contributions to mineralogy and petrology 104 (1990), S. 208-224 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract There is currently a dearth of reliable thermobarometers for many hornblende and plagioclase-bearing rocks such as granitoids and amphibolites. A semi-empirical thermodynamic evaluation of the available experimental data on amphibole+plagioclase assemblages leads to a new thermometer based on the Aliv content of amphibole coexisting with plagioclase in silica saturated rocks. The principal exchange vector in amphiboles as a function of temperature in both the natural and experimental studies is $$\left( {Na\square _{ - 1} } \right)^A \left( {AlSi_{ - 1} } \right)^{T1}$$ . We have analysed the data using 3 different amphibole activity models to calibrate the thermometer reactions 1. $$1. Edenite + 4 Quartz = Tremolite + Albite$$ 2. $$2. Pargasite + 4 Quartz = Hornblende + Albite.$$ The equilibrium relation for both (1) and (2) leads to the proposed new thermometer $$T = \frac{{0.677P - 48.98 + Y}}{{ - 0.0429 - 0.008314 ln K}} and K = \left( {\frac{{Si - 4}}{{8 - Si}}} \right)X_{Ab}^{Plag} ,$$ where Si is the number of atoms per formula unit in amphiboles, with P in kbar and T in K; the term Y represents plagioclase non-ideality, RTlnγab, from Darken's Quadratic formalism (DQF) with Y=0 for X ab〉0.5 and Y=-8.06+25.5(1-X ab)2 for X ab〈0.5. The best fits to the data were obtained by assuming complete coupling between Al on the T1 site and Na in the A site of amphibole, and the standard deviation of residuals in the fit is ±38°C. The thermometer is robust to ferric iron recalculation procedures from electron probe data and should yield temperatures of equilibration for hornblende-plagioclase assemblages with uncertainties of around ±75° C for rocks equilibrated at temperatures in the range 500°–1100° C. The thermometer should only be used in this temperature range and for assemblages with plagioclase less calcic than An92 and with amphiboles containing less than 7.8 Si atoms pfu. Good results have been attained on natural examples from greenschist to granulite facies metamorphic rocks as well as from a variety of mafic to acid intrusive and extrusive igneous rocks. Our analysis shows that the pressure dependence is poorly constrained and the equilibria are not suitable for barometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306444
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  • 2
    Electronic Resource
    Electronic Resource
    “Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer”—reply to the comment of Poli and Schmidt (1992)
    Springer
    Contributions to mineralogy and petrology 111 (1992), S. 278-282 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Conclusions Although only Aliv appears in our thermometer expression, this in no way infers that we believe tschermakite (or katophorite, kaersutite and other) substitutions to be unimportant. A careful reading of our earlier papers makes it clear that the reverse is true, e.g. Holland and Richardson 1979; Will et al. 1990a, b; Guiraud et al. 1990. Indeed in B and H (p. 211) we state that “natural and synthetic amphiboles are dominated by a combination of edenite, pargasite, hornblende and hastingsite substitutions”. What we endeavoured to point out was that because of the nature of reaction (1) and the use of mixing-on-sites activity models the extent of Al substitutions on M2 or Na on M4 do not materially influence our expression for K1 and consequently our thermometer. Certainly any sophisticated activity model for amphibole explicitly should account for all cross-site interactions between M-, Tl- and A-site cations, as alluded to by P and S in reference to Docka et al. (1987), as well as O3-site anions. However, such a day currently is well away and mixing-on-sites, with modifications as outlined above and to be detailed in T.J.B. Holland and J.D. Blundy (in preparation), seems rather promising for the purposes of amphibole thermometry. We do not share the rather negative and pessimistic outlook on activity models and thermobarometry implicit in P and S′ comments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348961
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  • 3
    Electronic Resource
    Electronic Resource
    A predictive model for rare earth element partitioning between clinopyroxene and anhydrous silicate melt (1997)
    Springer
    Contributions to mineralogy and petrology 129 (1997), S. 166-181 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract We present a quantitative model to describe the partitioning of rare earth elements (REE) and Y between clinopyroxene and anhydrous silicate melt as a function of pressure (P), temperature (T) and bulk composition (X). The model is based on the Brice (1975) equation, which relates the partition coefficient of element i (D i ) to that of element o (D o ) where the latter has the same ionic radius r o as the crystallographic site of interest, in this case the clinopyroxene M2 site: N A is Avogadro's number, E M2 is the Young's Modulus of the site, R is the gas constant and T is in K. Values of E M2 obtained by fitting the Brice equation to experimental REE partition coefficient patterns are in good agreement with those obtained from the well-known correlation between bulk modulus, metal-oxygen distance and cation charge. Using this relationship to constrain E M2 for 3+ cations and then fitting the Brice equation to those experimental data where 3 or more REE partition coefficients had been simultaneously measured we obtained 82 values of D o and r o . The latter was found to be a simple and crystallochemically reasonable function of clinopyroxene composition. We show that for any clinopyroxene-melt pair if D for one middle REE (e.g. Sm or Gd) is known then the Brice equation can be used to predict Ds for all the other REE, with uncertainties similar to those involved in the actual measurements. The model was generalised using thermodynamic descriptions of REE components in crystal and melt phases to estimate the free energy of fusion (ΔG f ) of the fictive REE components REEMgAlSiO6 and Na0.5REE0.5MgSi2O6. For the melt we find that 6-oxygen melt components (CaMgSi2O6,NaAlSi2O6, Mg3Si1.5O6 etc.) mix with constant activity coefficient over a wide range of natural compositions. Propagating ΔG f into the Brice model we obtain an expression for D o 3+ in terms of the atomic fraction of Mg on the clinopyroxene M1 site, the Mg-number of the melt, P and T. The D for any REE can be calculated from D o 3+ using the Brice equation. Over 92% of D REE (454 points) calculated in this way lie within a factor 0.63–1.59 of the experimental value. The approach can be extended to calculate D for any REE at a given P (≤6GPa) and T (12002038K) to within 0.60–1.66 times the true value given only the crystal and/or melt composition. The model has widespread applicability to geochemical modelling of all natural processes involving clinopyroxene, e.g. decompression mantle melting, enabling for the first time account to be taken of variations in partition coefficient in response to changing pressure, temperature and phase composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050330
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon–fluid equilibria and the oxidation state of the upper mantle (1991)
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 321-324 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] At relatively shallow levels in the mantle, equilibria between CO, CO2 and carbon could buffer f02 through the equilibria1 (termed CCO) ^C02 (la) where carbon is present either as graphite or diamond. At higher pressures CO2 and/or carbon should react with mantle silicates to produce ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/349321a0
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  • 5
    Electronic Resource
    Electronic Resource
    “Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer”: Reply to the comments of Hammarstrom and Zen, and Rutherford and Johnson (1992)
    Springer
    Contributions to mineralogy and petrology 111 (1992), S. 269-272 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Conclusions We reaffirm the barometric potential of our amphibole-plagioclase thermometer for rocks where (and only where) the final equilibration temperature is very well constrained. In the advantageous case of granitoids with simple thermal histories this temperature may be the wet granitoid solidus at the pressure of interest. We emphasise the need for careful petrographic assessment of equilibrium between plagioclase and amphibole before attempting total-Al barometry and recommend that a relatively large number of pairs are analysed for each sample. In rocks with complex post-consolidation or fluid-flow histories such barometry requires an independent means of determining amphibole equilibration temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00348959
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  • 6
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    (Table 1) Geochemical compositions of volcaniclastic sediments on an anhydrous basis for comparison from ODP Hole 129-801B (2016)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Keywords: 129-801B; Aluminium oxide; Aluminium oxide, standard deviation; Barium; Barium, standard deviation; Caesium; Caesium, standard deviation; Calcium oxide; Calcium oxide, standard deviation; Cerium; Cerium, standard deviation; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Dysprosium, standard deviation; Electron microprobe (EMP); Europium; Europium, standard deviation; Gadolinium; Gadolinium, standard deviation; Hafnium; Hafnium, standard deviation; Iron oxide, FeO; Iron oxide, FeO, standard deviation; Joides Resolution; LA-ICP-MS, Laser-ablation inductively coupled plasma mass spectrometer; Lanthanum; Lanthanum, standard deviation; Leg129; Loss on ignition; Lutetium; Magnesium oxide; Magnesium oxide, standard deviation; Manganese oxide; Manganese oxide, standard deviation; Neodymium; Neodymium, standard deviation; Niobium; Niobium, standard deviation; North Pacific Ocean; Ocean Drilling Program; ODP; Phosphorus pentoxide; Phosphorus pentoxide, standard deviation; Potassium oxide; Potassium oxide, standard deviation; Praseodymium; Praseodymium, standard deviation; Reference of data; Rubidium; Rubidium, standard deviation; Samarium; Samarium, standard deviation; Sample code/label; Scandium; Scandium, standard deviation; Silicon dioxide; Silicon dioxide, standard deviation; Sodium oxide; Sodium oxide, standard deviation; Strontium; Strontium, standard deviation; Tantalum; Tantalum, standard deviation; Thorium; Thorium, standard deviation; Titanium dioxide; Titanium dioxide, standard deviation; Total; Uranium; Uranium, standard deviation; Vanadium; Vanadium, standard deviation; Ytterbium; Ytterbium, standard deviation; Yttrium; Yttrium, standard deviation; Zirconium; Zirconium, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 102 data points
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  • 7
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    (Table S1) Geochemical analyses of voclaniclastic material and dredged seamount material from ODP Hole 129-801A and 129-801B (2016)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Keywords: 129-801A; 129-801B; Aluminium oxide; Calcium oxide; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Electron microprobe (EMP); Event label; Iron oxide, FeO; Joides Resolution; Leg129; Loss on ignition; Magnesium oxide; Manganese oxide; North Pacific Ocean; Ocean Drilling Program; ODP; Phosphorus pentoxide; Potassium oxide; Reference of data; Sample code/label; Silicon dioxide; Sodium oxide; Titanium dioxide; Total; Unit
    Type: Dataset
    Format: text/tab-separated-values, 284 data points
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  • 8
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    Geochemistry of subducted volcaniclastic sediments from Mariana arc magmas (2016)
    PANGAEA
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    Publication Date: 2024-02-02
    Description: The phase relations of natural volcaniclastic sediments from the west Pacific Ocean were investigated experimentally at conditions of 3-6 GPa and 800-900 °C with 10 wt.% added H2O (in addition to ~ 10 wt.% structurally-bound H2O) to induce hydrous melting. Volcaniclastic sediments are shown to produce a sub-solidus assemblage of garnet, clinopyroxene, biotite, quartz/coesite and the accessory phases rutile ± Fe-Ti oxide ± apatite ± monazite ± zircon. Hydrous melt appears at temperatures exceeding 800-850 °C, irrespective of pressure. The melt-producing reaction consumes clinopyroxene, biotite and quartz/coesite and produces orthopyroxene. These phase relations differ from those of pelagic clays and K-bearing mid ocean ridge basalts (e.g. altered oceanic crust) that contain phengite, rather than biotite, as a sub-solidus phase. Despite their relatively high melt productivity, the wet solidus for volcaniclastic sediments is found to be higher (825-850 °C) than other marine sediments (700-750 °C) at 3 GPa. This trend is reversed at high-pressure conditions (6 GPa) where the biotite melting reaction occurs at lower temperatures (800-850 °C) than the phengite melting reaction (900-1000 °C). Trace element data was obtained from the 3 GPa run products, showing that partial melts are depleted in heavy rare earth elements (REE) and high field strength elements (HFSE), due to the presence of residual garnet and rutile, and are enriched in large ion lithophile elements (LILE), except for Sr and Ba. This is in contrast to previous experimental studies on pelagic sediments at sub-arc depths, where Sr and Ba are among the most enriched trace elements in glasses. This behavior can be partly attributed to the presence of residual apatite, which also host some light REE in our supra-solidus residues. Our new experimental results account for a wide range of trace element and U-series geochemical features of the sedimentary component of the Mariana arc magmas, including imparting a substantial Nb anomaly to melts from an anomaly-free protolith.
    Keywords: Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 9
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    Subvolcanic plumbing systems imaged through crystal size distributions (2011)
    Geological Society of America (GSA)
    Details
    Publication Date: 2011-04-01
    Description: The configuration of subvolcanic magma storage regions exercises a fundamental control on eruptive style and hazard. Such regions can be imaged remotely, using seismic, geodetic, or magnetotelluric methods, although these are far from routine and rarely unambiguous. The textures of erupted volcanic rocks, as quantified through crystal size distributions (CSD), provide space- and time-integrated information on subvolcanic plumbing systems, although these data cannot be used readily for reconstruction of key parameters such as conduit geometry or magma chamber depth. Here we develop a numerical approach to interpretation of CSD in products of steady eruptions, based on crystallization kinetics and hydrodynamic flow simulation, to image subvolcanic plumbing systems. The method requires knowledge of magma properties, crystal growth kinetics (measured experimentally), and discharge rate (measured observationally). The method is applicable to steady-state eruptive regimes. Distributions of pressure, temperature, crystal content, and conduit cross-section area with depth are obtained from a CSD from a sample erupted from Mount St. Helens volcano, USA. Values of average conduit diameter ([~]30 m) and magma chamber depth ([~]14 km below the summit) are in good agreement with independent estimates.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 10
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    Taking the pulse of volcanic eruptions using plagioclase glomerocrysts (2020)
    Elsevier
    Details
    Publication Date: 2020-12-01
    Print ISSN: 0012-821X
    Electronic ISSN: 1385-013X
    Topics: Geosciences , Physics
    Published by Elsevier
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