The effect of titanium on the silica content and on mineral-liquid partitioning of mantle-equilibrated melts

Xirouchakis, Dimitrios; Hirschmann, M. M.; Simpson, J. A.

doi:10.1016/s0016-7037(00)00549-4

Cited by 78 publications

(57 citation statements)

References 64 publications

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“…In experiments on lunar low-Ti ultramafic glasses (Fig 2-6) K is consistent with other studies of high-Ti compositions [Longhi et al, 1978, Delano, 1980, Xirouchakis et al, 2001, Wagner and Grove, 1997, Canil and Bellis, 2008 Jones [1988] to determine the best fit stoichiometry of the Fe-Ti melt complex by calculating the moles of Fe that must be subtracted from the melt to achieve a reference K We have done these calculations using the following equation:…”

Section: Variations In Mineral-melt Fe-mg Exhangesupporting

confidence: 80%

“…In Figure 2-7b we show that all of the data sets (including the low FeO Xirouchakis et al [2001] data) follow the same general trend. This would suggest that there is not a specific atomic proportion of the Fe-Ti complex.…”

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 56%

“…However, the study of Xirouchakis et al [2001] used an experimental composition with a lower amount of , and their data is best fit by a line that matches a 7:1 ratio of Ti:Fe. There is a sharp shift in the behavior of Ti in the melt at about 7 mol% TiO 2 , and below this value all the data sets on high-Ti liquids show no evidence for coupling of Fe with Ti within error.…”

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 99%

“…[Longhi et al, 1978, Delano, 1980, Jones, 1988, Xirouchakis et al, 2001. However other authors have suggested that it is not the increased Ti content that affects the K F e−M g D , but actually the low silica contents that necessarily accompany the increased Ti [Longhi et al, 1978, Toplis, 2005.…”

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 99%

“…Dickinson and Hess [1985] and Gaetani et al [2008] used analogue liquids to determine the saturation of rutile in a range of silicate liquids. Xirouchakis et al [2001] and Longhi et al [1978] explored the effect of TiO 2 on major element partitioning in olivine-liquid equilibrium. Longhi et al [1972] performed high-pressure experiments on Apollo 17 mare basalts and Green et al [1975], Delano [1980, Wagner and Grove [1997] carried out studies on the Apollo 17 orange, Apollo 15 red, and Apollo 14 black glasses respectively.…”

Section: Introductionmentioning

confidence: 99%

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Experimental studies of melting and crystallization processes in planetary interiors

Krawczynski¹

2011

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Melting and crystallization processes on the Earth and Moon are explored in this thesis, and the topics of melt generation, transport, and crystallization are discussed in three distinct geologic environments: the Moon's mantle, the Greenland ice sheet, and the Earth's crust. Experiments have been conducted to determine the conditions of origin for two high-titanium magmas from the Moon. The lunar experiments (Chapter 2) were designed to explore the effects of variable oxygen fugacity (f O 2 ) on the high pressure and high temperature crystallization of olivine and orthopyroxene in high-Ti magmas. The results of these experiments showed that the source regions for the high-Ti lunar magmas are distributed both laterally and vertically within the lunar mantle, and that it is critical to estimate the pre-eruptive oxygen fugacity in order to determine true depth of origin for these magmas within the lunar mantle. Chapter 3 models the behavior of water flow through the Greenland ice sheet driven by hydrofracture of water through ice. The results show that melt water in the ablation zone of Greenland has almost immediate access to the base of the ice sheet in areas with up two kilometers of ice. Chapter 4 is an experimental study of two hydrous high-silica mantle melts from the Mt. Shasta, CA region. Crystallization is simulated at H 2 O saturated conditions at all crustal depths, and a new geobarometerhygrometer based on amphibole magnesium number is calibrated. In Chapter 5 I use the new barometer to study a suite of mafic enclaves from the Mt. Shasta region, and apply it to amphiboles in these enclaves. Evidence for pre-eruptive H 2 O contents of up to 14 wt% is presented, and bulk chemical analyses of the inclusions are used to show that extensive magma mixing has occurred at all crustal depths up to 35 km beneath Mt. Shasta. Tim Grove. I can never repay all the knowledge, time, trust, friendship, and guidance that you have freely given to me. You are more than an advisor; you made me feel like family. Your endless energy and passion for petrology has rubbed off on me, and has reinforced my desire to pursue the origins of igneous rocks. The time we spent in the field is the most fun I have ever had, and has taught me that geology necessarily happens in the field as well as the lab. Those experiences will shape the future of my geologic career. In the lab you trusted me to make my own scientific decisions, and then patiently helped me fix all the equipment I broke and set me straight on some of the wacky decisions I made! You read all of the early drafts of this thesis, practiced all my talks over and over with me, and at times I know it was painful, but you shaped me into a scientist. I am truly honored that my thesis will always sit right above your desk, with all of your great students. I hope that someday I will live up to your expectations of me and I promise to pass on the dedication and care to my own students that you have showed me. In the future, stop by for a visit in my thermodynamics/petrology/...

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Section: Variations In Mineral-melt Fe-mg Exhangesupporting

confidence: 80%

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 56%

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 99%

Section: Variations In Mineral-melt Fe-mg Exhangementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental studies of melting and crystallization processes in planetary interiors

Krawczynski¹

2011

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The thermodynamics of iron and magnesium partitioning between olivine and liquid: criteria for assessing and predicting equilibrium in natural and experimental systems

Toplis

2004

Contrib Mineral Petrol

416

268

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Titanium solubility in olivine in the system TiO2–MgO–SiO2: no evidence for an ultra-deep origin of Ti-bearing olivine

Hermann

O’Neill

Berry

2004

Contrib Mineral Petrol

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The finding of ilmenite rods in olivine from orogenic peridotites has sparked a discussion about the processes of incorporation and exsolution of titanium in olivine. We have experimentally investigated the solubility of Ti in olivine as a function of composition, temperature and pressure in the synthetic TiO 2 -MgO-SiO 2 system. Experiments at atmospheric pressure in the temperature range 1,200-1,500°C showed that the highest concentration of TiO 2 is obtained when olivine coexists with spinel (Mg 2 TiO 4 ). The amount of TiO 2 in olivine in the assemblages olivine + spinel + periclase and olivine + spinel + ilmenite at 1,500°C was 1.25 wt.%. Changes in the coexisting phases and decreasing temperature result in a significant reduction of the Ti solubility. Olivine coexisting with pseudobrookite (MgTi 2 O 5 ) and a Ti-Si-rich melt at 1,500°C displays a fourfold lower TiO 2 content than when buffered with spinel. A similar decrease in solubility is obtained by a decrease in temperature to 1,200°C. There is a negative correlation between Ti and Si and no correlation between Ti and Mg in Ti-bearing olivine. Together with the established phase relations this suggests that there is a direct substitution of Ti for Si at these temperatures, such that the substituting component has the stoichiometry Mg 2 TiO 4 . The unit cell volume of olivine increases systematically with increasing TiO 2 content demonstrating that the measured TiO 2 contents in olivine are not caused by micro-inclusions but by incorporation of Ti in the olivine structure. Least squares fitting of 20 olivine unit cell volumes against the Ti content yield the relation: V (A ˚3)=290.12(1) + 23.67(85) N Ti. The partial molar volume of end-member Mg 2 TiO 4 olivine (N Ti =1) is thus 47.24±0.13 cm 3 . The change of the Ti solubilty in olivine coexistent with rutile and orthopyroxene with pressure was investigated by piston cylinder experiments at 1,400°C from 15 to 55 kbar. There is no increase in TiO 2 contents with pressure and in all the experiments olivine contains $0.2 wt.% TiO 2 . Moreover, a thermodynamic analysis indicates that Ti contents of olivine coexisting with rutile and orthopyroxene should decrease rather than increase with increasing pressure. These data indicate that the ilmenite exsolution observed in some natural olivine does not signify an ultra-deep origin of peridotite massifs.

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The effect of titanium on the silica content and on mineral-liquid partitioning of mantle-equilibrated melts

Cited by 78 publications

References 64 publications

Experimental studies of melting and crystallization processes in planetary interiors

Experimental studies of melting and crystallization processes in planetary interiors

The thermodynamics of iron and magnesium partitioning between olivine and liquid: criteria for assessing and predicting equilibrium in natural and experimental systems

Titanium solubility in olivine in the system TiO2–MgO–SiO2: no evidence for an ultra-deep origin of Ti-bearing olivine

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