Experimental study of liquid evolution in an Fe-rich,layered mafic intrusion: constraints of Fe-Ti oxide precipitation on the T-fO 2 and T-ϱ paths of tholeiitic magmas     

Don Snyder  Ian S. E. Carmichael  R. A. Wiebe 《Contributions to Mineralogy and Petrology》1993,113(1):73-86

The Newark Island layered intrusion, a composite intrusion displaying a similar fractionation sequence to the Skaergaard, has both dikes which preserved liquids fed into the intrusion and chilled pillows of liquids resident in the chamber. This study reports experimentally determined one atmosphere liquid lines of descent of these compositions as a function of oxygen fugacity which varies from QFM (quartz-fayalite-magnetite) to 0.5 log₁₀ units above IW (iron-wustite). These experiments reveal a strong oxygen fugacity dependence on the order of appearance and relative abundances of the Fe–Ti oxide minerals. Titanomagnetite saturates prior to ilmenite at QFM, but the order is reversed at lower oxygen fugacities. In the layered series of the Newark Island intrusion, ilmenite arrives shortly before titanomagnetite and the titanomagnetite/ilmenite ratio decreases monotonically after the cumulus appearance of titanomagnetite. Comparison of the crystallization sequence in the intrusion with that of the experiments requires that the oxygen fugacity in the intrusion increased relative to QFM before titanomagnetite saturation and decreased afterward, but always remained between the QFM and IW buffers. Similar trends in the modes of the Fe–Ti oxides (ilmenite and titanomagnetite) in the Skaergaard, Kiglapait, and Somerset Dam intrusions along with Fe₂O₃/FeO ratios in MORBs suggest that such a temperature-oxygen fugacity path may be typical of tholeiitic magma differentiation. Calculations of the temperature-density paths of the experimental liquids indicate that, at all possible oxygen fugacities, the density must have decreased abruptly after Fe–Ti oxide saturation. Accordingly, liquids replenishing the intrusion after Fe–Ti oxide saturation should pond at the bottom of the chamber, quenching against older cumulates. Field observation at the Newark Island intrusion confirm this prediction. The similarities in the fractionation paths of several other layered intrusions to that of the Newark Island intrusion suggest that the density of the liquids in these intrusions also decreased after Fe–Ti oxide saturation. Experiments on a suggested initial Skaergaard liquid are consistent with this model.  相似文献   

Sr isotopic evidence for a multi-source origin of the potassic magmas in the neapolitan area (S. Italy)     

Massimo Cortini  O. Don Hermes 《Contributions to Mineralogy and Petrology》1981,77(1):47-55

New Sr isotopic data on lavas and xenoliths from Somma-Vesuvius and other nearby volcanic areas (Phlegrean Fields and Ischia) are presented. Chemical and isotopic evidences show that not all the Phlegrean Fields rocks belong to the low K series, but some of them may be interpreted as low pressure differentiates of Somma magmas, i.e. as a part of the high K series. Two rock groups are defined in the Ischia low K series, which are well identified both in time and in chemical and isotopic features, and cannot be derived from the same magma source. The low K series in the studied area generally has lower Sr isotopic values than the high K series.Historical Vesuvian lavas show two distinct linear trends with negative slopes when⁸⁷Sr/⁸⁶Sr ratios are plotted against their ages of eruption. Such trends are interpreted to result from mixing of magmas in two separate reservoirs. Evidence from the Vesuvian ejecta shows that Somma-Vesuvius magmas underwent high or low pressure fractionation, in connection with different events of the Vesuvian activity. Distinct magma reservoirs developed episodically at different depths. Isotopic and geochemical evidences do not favour large scale assimilation of crustal materials by Somma-Vesuvius magmas, but instead appear to reflect mantle characteristics.A minimum of three different (inhomogeneous) source regions is necessary to account for the isotopic features of the studied rocks.  相似文献   

Fractionation paths of Atka (Aleutians) high-alumina basalts: Constraints from phase relations     

Don R. Baker  David H. Eggler 《Journal of Volcanology and Geothermal Research》1983,18(1-4)

An Aleutian high-alumina basalt from the island of Atka at one atmosphere crystallizes plagioclase (1275°C) followed by olivine (1170°C) and clinopyroxene (1115°C). At oxygen fugacities along NNO, magnetite crystallizes below 1070°C, but its liquidus increases to at least 1175°C at an oxygen fugacity two log units above NNO. Phase relations at two kilobars pressure of melts containing small amounts of water are similar, although orthopyroxene and magnetite are observed to follow clinopyroxene. Amphibole crystallizes at near-liquidus temperatures only at water contents of melts approaching 4.5%. Amphibole assumes the liquidus in melts containing 5% water.Anhydrous melts crystallize plagioclase to 19 kbar, where garnet and clinopyroxene assume the liquidus. Olivine yields to clinopyroxene as the highest-temperature subliquidus phase at about 9 kbar.The array of compositions of basaltic Atka rocks, as displayed on appropriate pseudoternary projections, can be interpreted as a crystal fractionation path at moderate pressure (8 kbar) and small melt-water contents. The interpreted fractionating minerals are olivine, clinopyroxene, plagioclase, and (probably) magnetite. (The actual phenocrysts in Atka basalts like AT-1, which lacks phenocrystic clinopyroxene, must have crystallized at pressure less than 8 kbar, however.) The compositions of two-pyroxene andesites from Atka can be interpreted to lie on a lower-pressure fractionation trend at melt water contents of 2–3%. Such water contents are consistent with the complete absence of amphibole in any Atka rocks and are suggestive that water contents of the basaltic magmas, if the basalts are parental to the andesites, were 1–2%.  相似文献   

Programmable Hand Calculator Programs for Pumping and Injection Wells:     

Don L. Warner  M. Gene Yow 《Ground water》1980,18(5):438-443

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Comments on: “The partitioning of nickel between olivine and silicate melt” by S.R. Hart and K.E. Davis     

Don Elthon  W. Ian Ridley 《Earth and Planetary Science Letters》1979,44(1):162-164

We study a set of very high-quality records of first-order overtone Rayleigh waves from the deep-focus earthquake of September 29, 1973, in the Japan Sea. Standard surface wave techniques are used with these overtones, treated as individual seismic phases, to retrieve radiation pattern, Q, moment and phase velocity. A figure of M₀ = (6.7 ± 1.4) × 10²⁷dyn-cm is obtained, in total agreement with published values computed from either P waves, or fundamental Rayleigh waves. We also demonstrate the feasibility of using overtones as individual seismic phases in order to investigate their dispersion and attenuation properties.  相似文献   

Determination of quantitative cation distribution in orthopyroxenes from electronic absorption spectra     

Don S. Goldman  George R. Rossman 《Physics and Chemistry of Minerals》1979,4(1):43-53

Electronic and Mössbauer absorption spectra and electron microprobe data are correlated for iron-bearing orthopyroxenes. The correlation provides a means of quantitatively determining the distribution of Fe²⁺ between the M(1) and M(2) sites of orthopyroxene crystals from electronic spectra and electron microprobe analysis. The electronic spectra are used to analyze the changes in the Fe²⁺ distribution produced during heating experiments and confirm earlier results from Mössbauer spectra. Two components of the spin-allowed transition of Fe²⁺ in the M(1) site are identified at about 13,000 cm^?1 and 8,500 cm^?1 in γ. Molar absorptivity (?) values for all spin-allowed Fe²⁺ absorption bands in the near-infrared region are determined. The M(2) Fe²⁺ band at ～5,000 cm^?1 in β is the analytically most useful for site occupancy determinations. It remains linear with concentration (?=9.65) over the entire compositional range. The band at ～10,500 cm^?1 in α is the most sensitive to M(2) Fe²⁺ concentration (?=40.8), but deviates from linearity at high iron concentrations. The origins of spin-forbidden transitions in the visible region are examined.  相似文献   

Thermodynamic analysis of the system Na₂O-K₂O-CaO-Al₂O₃-SiO₂-H₂O-F₂O_?1: Stability of fluorine-bearing minerals in felsic igneous suites     

David Dolej  Don R. Baker 《Contributions to Mineralogy and Petrology》2004,146(6):762-778

Thermodynamic analysis of the system Na₂O-K₂O-CaO-Al₂O₃-SiO₂-H₂O-F₂O_–1 provides phase equilibria and solidus compatibilities of rock-forming silicates and fluorides in evolved granitic systems and associated hydrothermal processes. The interaction of fluorine with aluminosilicate melts and solids corresponds to progressive fluorination of their constituent oxides by the thermodynamic component F₂O_–1. The chemical potential (F₂O_–1) buffered by reaction of the type: MO_n/2 (s)+n/2 [F₂O_–1]=MF_n (s, g) where M=K, Na, Ca, Al, Si, explains the sequential formation of fluorides: carobbiite, villiaumite, fluorite, AlF₃, SiF₄ as well as the common coexistence of alkali- and alkali-earth fluorides with rock-forming aluminosilicates. Formation of fluorine-bearing minerals first starts in peralkaline silica-undersaturated, proceeds in peraluminous silica-oversaturated compositions and causes progressive destabilization of nepheline, albite and quartz, in favour of villiaumite, cryolite, topaz, chiolite. Additionally, it implies the increase of buffered fluorine solubilities in silicate melts or aqueous fluids from peralkaline silica-undersaturated to peraluminous silica-oversaturated environments. Subsolidus equilibria reveal several incompatibilities: (i) topaz is unstable with nepheline or villiaumite; (ii) chiolite is not compatible with albite because it only occurs only at very high F₂O_–1 levels. The stability of topaz, fluorite, cryolite and villiaumite in natural felsic systems is related to their peralkalinity (peraluminosity), calcia and silica activity, and linked by corresponding chemical potentials to rock-forming mineral buffers. Villiaumite is stable in strongly peralkaline and Ca-poor compositions (An_<0.001). Similarly, cryolite stability requires coexistence with nearly-pure albite (An_<2). Granitic rocks with Ca-bearing plagioclase (An_>5) saturate with topaz or fluorite. Crystallization of topaz is restricted to peraluminous conditions, consistent with the presence of Li-micas or anhydrous aluminosilicates (cordierite, garnet, andalusite). Fluorite is predicted to be stable in peraluminous biotite granites, amphibole-, clinopyroxene- or titanite-bearing calc-alkaline suites as well as in peralkaline granitic and syenitic rocks. Fluorine concentrations in felsic melts buffered by the coexistence of F-bearing minerals and feldspars increase from peralkaline through metaluminous to mildly peraluminous compositions. At low-temperature conditions, the hydrothermal evolution of peraluminous granitic and greisen systems is controlled by white mica-feldspar-fluoride equilibria. With decreasing temperature, topaz gradually breaks down via: (i) (OH)F_–1 substitution and fluorine transfer to fluorite by decalcification of plagioclase below 600 °C, (ii) formation of muscovite and additional fluorite at 475–315 °C, and (iii) formation of paragonite and cryolite, consuming F-rich topaz and albite below 315 °C. These equilibria explain the absence of magmatic fluorite in Ca-bearing topaz granitic rocks; its abundance in hydrothermal rocks is due to: (i) closed-system defluorination of topaz, (ii) open-system decalcification of plagioclase or (iii) hydrolytic alteration. These results provide a complete framework for the investigation of fluorine-bearing mineral stabilities in felsic igneous suites.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material.Editorial responsibility: T.L. Grove  相似文献   

WASP hunts planets     

Don Pollacco 《Astronomy& Geophysics》2005,46(1):1.19-1.22

Don Pollacco reviews progress so far on SuperWASP, a wide-field astronomy project designed to detect extrasolar planets and more, built with a lot of hard work – and a little help from eBay.  相似文献   

Thermodynamic modeling of melts in the system Na₂O-NaAlO₂-SiO₂-F₂O₋₁     

David Dolejš  Don R. Baker 《Geochimica et cosmochimica acta》2005,69(23):5537-5556

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The effect of halogens on Zr diffusion and zircon dissolution in hydrous metaluminous granitic melts   总被引：1，自引：0，他引：1  

Don R. Baker  Aida Conte  Carmela Freda  Luisa Ottolini 《Contributions to Mineralogy and Petrology》2002,142(6):666-678

Diffusion of Zr and zircon solubility in hydrous, containing approximately 4.5 wt% H₂O, metaluminous granitic melts with halogens, either 0.35 wt% Cl (LCl) or 1.2 wt% F (MRF), and in a halogen-free melt (LCO) were measured at 1.0 GPa and temperatures between 1,050 and 1,400 °C in a piston-cylinder apparatus using the zircon dissolution technique. Arrhenius equations for Zr diffusion in each hydrous melt composition are, for LCO with 4.4ǂ.4 wt% H₂O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaI4aaocqaI4aaocqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaIZaWmcqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabiIda4aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIXaqmcqaI0aancqaIWaamcqGGUaGlcqaIXa % qmcqGHXcqScqaIZaWmcqaIZaWmcqGGUaGlcqaI5aqoaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!571F! D = 2.88 ±0.03x10 ^{- 8} exp( [( - 140.1 ±33.9)/(RT)] )D = 2.88 \pm 0.03x10^{ - 8} \exp \left( {{{ - 140.1 \pm 33.9} \over {RT}}} \right) , for LCl with 4.5ǂ.5 wt% H₂O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaIZaWmcqaIZaWmcqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaI1aqncqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabisda0aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIYaGmcqaI1aqncqaI0aancqGGUaGlcqaI4a % aocqGHXcqScqaI2aGncqaI0aancqGGUaGlcqaIXaqmaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!5719! D = 2.33 ±0.05x10 ^{- 4} exp( [( - 254.8 ±64.1)/(RT)] )D = 2.33 \pm 0.05x10^{ - 4} \exp \left( {{{ - 254.8 \pm 64.1} \over {RT}}} \right) and for MRF with 4.9ǂ.3 wt% H₂O: % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacqWGebarcqGH9aqpcq % aIYaGmcqGGUaGlcqaI1aqncqaI0aancqGHXcqScqaIWaamcqGGUaGl % cqaIWaamcqaIZaWmcqWG4baEcqaIXaqmcqaIWaamdaahaaWcbeqaai % abgkHiTiabiwda1aaakiGbcwgaLjabcIha4jabcchaWnaabmaabaWa % aSaaaeaacqGHsislcqaIYaGmcqaIYaGmcqaIZaWmcqGGUaGlcqaI4a % aocqGHXcqScqaIXaqmcqaI1aqncqGGUaGlcqaI1aqnaeaacqWGsbGu % cqWGubavaaaacaGLOaGaayzkaaaaaa!5715! D = 2.54 ±0.03x10 ^{- 5} exp( [( - 223.8 ±15.5)/(RT)] )D = 2.54 \pm 0.03x10^{ - 5} \exp \left( {{{ - 223.8 \pm 15.5} \over {RT}}} \right) . Solubilities determined by the dissolution technique were reversed for LCO +4.5ǂ.5 wt% H₂O by crystallization of a Zr-enriched glass of LCO composition at 1,200 and 1,050 °C at 1.0 GPa. The solubility data were used to calculate partition coefficients of Zr between zircon and hydrous melt, which are given by the following expressions: for LCO % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGOnayJa % eG4mamZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 1aqncqGGUaGlcqaI4aaocqaI3aWnaaa!5924! lnD_Zr^zircon/melt = 1.63( [10000/(T)] ) - 5.87\ln D_{Zr}^{zircon/melt} = 1.63\left( {{{10000} \over T}} \right) - 5.87 , for LCl % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGinaqJa % eG4naCZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 0aancqGGUaGlcqaI3aWncqaI1aqnaaa!5920! lnD_Zr^zircon/melt = 1.47( [10000/(T)] ) - 4.75\ln D_{Zr}^{zircon/melt} = 1.47\left( {{{10000} \over T}} \right) - 4.75 and, for MRF by % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavP1wzZbItLDhis9wBH5garm % Wu51MyVXgaruWqVvNCPvMCG4uz3bqee0evGueE0jxyaibaieYlf9ir % Veeu0dXdh9vqqj-hEeeu0xXdbba9ev6pc9fs0-rqaqpepmKs4qpepe % I8kaL8kuc9pgc9q8qqaq-dhH6hb9hs0dXdHu6deP0u0-vr0-vr0db8 % meaabaqaciGacaGaaeaabaWaaeaaeaaakeaacyGGSbaBcqGGUbGBcq % WGebardaqhaaWcbaGaemOwaOLaemOCaihabaGaemOEaONaemyAaKMa % emOCaiNaem4yamMaem4Ba8MaemOBa4Maei4la8IaemyBa0Maemyzau % MaemiBaWMaemiDaqhaaOGaeyypa0JaeGymaeJaeiOla4IaeGinaqJa % eG4naCZaaeWaaeaadaWcaaqaaiabigdaXiabicdaWiabicdaWiabic % daWiabicdaWaqaaiabdsfaubaaaiaawIcacaGLPaaacqGHsislcqaI % 0aancqGGUaGlcqaI5aqocqaIXaqmaaa!591C! lnD_Zr^zircon/melt = 1.47( [10000/(T)] ) - 4.91\ln D_{Zr}^{zircon/melt} = 1.47\left( {{{10000} \over T}} \right) - 4.91 . Experiments on the same compositions, but with water contents down to 0.5 wt%, demonstrated reductions in both the diffusion coefficient of Zr and zircon solubility in the melt. The addition of halogens at the concentration levels studied to metaluminous melts has a small effect on either the diffusion of Zr in the melt, or the solubility of zircon at all water concentrations and temperatures investigated. At 800 °C, the calculated diffusion coefficient of Zr is lowest in LCl, 9᎒^-17 m² s^-1, and is highest in LCO, 4᎒^-15 m² s^-1. Extrapolation of the halogen-free solubility data to a magmatic temperature of 800 °C yields solubilities of approximately one-third of those directly measured in similar compositions, predicted by earlier studies of zircon dissolution and based upon analyses of natural rocks. This discrepancy is attributed to the higher oxygen fugacity of the experiments of this study compared with previous studies and nature, and the effect of oxygen fugacity on the structural role of iron in the melt, which, in turn, affects zircon solubility, but does not significantly affect Zr diffusion.  相似文献