Rutile Solubility Research Articles

Solubility of apatite, monazite, zircon, and rutile in supercritical aqueous fluids with implications for subduction zone geochemistry

Solubilities of accessory minerals (apatite, monazite, zircon and rutile) in supercritical aqueous fluids have been measured to evaluate the role of these fluids in the mobilization of accessory mineral-hosted trace elements. We have characterized the effects on solubility of pH, X H 2 O (addition of CO 2 ), pressure ( P = 1.0-3.0 GPa), temperature ( T =800-1200 °C), and dissolved silicate and NaCl concentration. Fluorapatite solubility in pure H 2 O is low, not more than 0.4 wt% at all conditions studied, but increases strongly with decreasing pH. Changes in P, T, X H 2 O M NaCl (the molality of NaCl), and dissolved silicate concentration have comparatively little effect on apatite solubility. Monazite is even less soluble in H 2 O (not more than 0.2 wt% ). Limited data suggests that monazite solubility increases with increasing P and T and with decreasing pH, but is insensitive to M NaCl . Zircon reacts with H 2 O to form baddeleyite (ZrO 2 ) + silica-rich fluid. ZrO 2 solubility in H 2 O and 1 m HCl is less than 0.2 wt% . Zircon, and therefore ZrO 2 , solubility in quartz-saturated fluids± HCl ±NaCl and in H 2 O -CO 2 fluids is also very low. Rutile is more soluble than the other minerals examined, in the wt% range, and its solubility increases with increasing P and T . Results indicate that high P-T aqueous fluids can dissolve significant amounts of Ti but very little Zr, and little phosphate unless the fluids are acidic. In most cases, apatite, monazite and zircon will remain present during episodes of aqueous fluid metasomatism and therefore will exert control, as ‘residual phases’, over element distribution. The higher solubility of rutile relative to other accessory minerals at high pressure may result in the depletion of high field strength elements relative to large ion lithophile elements observed in subduction zone volcanics.

Rutile saturation in magmas: implications for Ti [sbnd]Nb [sbnd]Ta depletion in island-arc basalts

The TiO 2 contents of rutile-saturated melts ranging from basalt to rhyodacite have been investigated at P = 8–30 kbar and T = 1000–1300°C under hydrous, CO 2-saturated, and volatile-absent conditions. Dissolved TiO 2 is positively correlated with T and not strongly dependent on P total. For fixed P and T, TiO 2 content decreases markedly as the melts become more felsic. The distribution of TiO 2 between rutile and liquid, expressed as a wt.% concentration ratio, D (rut/liq), is given by: In D = −3.16 + (9373T) + 0.026P − 0.152FM where T is in Kelvins, P in kbar and FM is a melt composition parameter, FM = [Na+K+ 2(Ca+Fe+Mg)]/Al· 1/Si in which the chemical symbols represent cation fractions. The first term expresses the competition of aluminate and titanate anions for charge-compensating cations, and the second term expresses the inverse dependence of dissolved TiO 2 on SiO 2 content. There is no apparent dependence of rutile solubility on water content. For ranges of probable solidus conditions, rutile saturation in basaltic, andesitic, and dacitic liquids requires 7–9, 5–7, and 1–3 wt.% TiO 2, respectively. These concentrations are well in excess of those found in the respective rock types, so depletion in Nb, Ta, and Ti and reduced Nb/U and Nb/Th ratios in volcanic rocks erupted at convergent plate margins cannot be attributed to residual rutile in their source regions. Thus, Nb, Ta and Ti depletion must be an inherent property of the source region. We suggest that the island-arc source region has been depleted in Nb and Ta by a previous episode of melt extraction (MORB), zoning refining, or equilibration with a percolating melt or fluid. Such a process markedly depletes the LILE and HFSE element concentrations in the residuum, but ratios such as Nb/U, Nb/Th and U/Th remain relatively constant due to similar solid-melt partition coefficients. The depletion of Nb relative to Th in the source regions of island-arc magmas occurs during hybridization of the source by rutile-saturated (Nb/Ta-depleted) melts or aqueous fluids. If the hybridizing agent is a melt, a relatively felsic composition, produced under low T (900°) hydrous conditions, is required.

Rutile solubility and titanium coordination in silicate melts

The solubility of rutile has been determined in a series of compositions in the K 2O-Al 2O 3-SiO 2 system ( K ∗ = K 2O (K 2O + Al 2O 3) = 0.38–0.90), and the CaO-Al 2O 3-SiO 2 system ( C ∗ = CaO (CaO + Al 2O 3) = 0.47–0.59 ). Isothermal results in the KAS system at 1325°C, 1400°C, and 1475°C show rutile solubility to be a strong function of the K ∗ ratio. For example, at 1475°C the amount of TiO 2 required for rutile saturation varies from 9.5 wt% ( K ∗ = 0.38 ) to 11.5 wt% ( K ∗ = 0.48 ) to 41.2 wt% ( K ∗ = 0.90 ). In the CAS system at 1475°C, rutile solubility is not a strong function of C ∗ . The amount of TiO 2 required for saturation varies from 14 wt% ( C ∗ = 0.48 ) to 16.2 wt% ( C ∗ = 0.59 ). The solubility changes in KAS melts are interpreted to be due to the formation of strong complexes between Ti and K + in excess of that needed to charge balance Al 3+. The suggested stoichiometry of this complex is K 2Ti 2O 5 or K 2Ti 3O 7. In CAS melts, the data suggest that Ca 2+ in excess of A1 3+ is not as effective at complexing with Ti as is K +. The greater solubility of rutile in CAS melts when C ∗ is less than 0.54 compared to KAS melts of equal K ∗ ratio results primarily from competition between Ti and Al for complexing cations (Ca vs. K). TiK β x-ray emission spectra of KAS glasses ( K ∗ = 0.43–0.60 ) with 7 mole% added TiO 2, rutile, and Ba 2TiO 4, demonstrate that the average Ti-O bond length in these glasses is equal to that of rutile rather than Ba 2TiO 4, implying that Ti in these compositions is 6-fold rather than 4-fold coordinated. Re-examination of published spectroscopic data in light of these results and the solubility data, suggests that the 6-fold coordination polyhedron of Ti is highly distorted, with at least one Ti-O bond grossly undersatisfied in terms of Pauling's rules.

Crystal Growth of Rutile (TiO<sub>2</sub>) by Flux Method

Single crystals of rutile (TiO2) were grown from several fluxes. The good results were obtained with Li2O-MoO3 flux systems. Using Li2O-m MoO3 fluxes, the habit and color of growing crystals vary with the amount of MoO3, which bring with it single crystals comparatively large in size. They vary continuously in form and color, from needle-like transparent crystal to prism-like and short-prism-like, black or opaque crystals.The growth experiments were carried out by slow-cooling method, temperature of growth being 1250°C to 800°C and cooling rate with 7°C/hr. The grown crystals obtained in such a method have needle-like habit 15 to 20mm in length elongated to c-axis and prism-like 1.5mm in diameter and 10mm in length, both being comparatively large in size and transparent free from inclusions.The solubility of rutile was measured from 1000° to 1300°C in Li2O-2MoO3 solvent, and also flux composition was varied from m=1 to m=3 at constant temperature 1150°C. The solubility was found to slightly increased dependent on MoO3 content. The dependence on temperature was found to almost linearly increased ranging from 1200° to 1300°C.

Education and Society in Modern France.W. R. Fraser

Previous articleNext article No AccessBook ReviewsEducation and Society in Modern France. W. R. Fraser C. Arnold AndersonC. Arnold Anderson Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by American Journal of Sociology Volume 70, Number 4Jan., 1965 Article DOIhttps://doi.org/10.1086/223898 Views: 2Total views on this site Citations: 13Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Vikt. L. Barsukov Modeling of geochemical processes occurred during the formation of the Schlema deposit, Erzgebirge. II. Formation of pre-uranium veins, Geochemistry International 44, no.1212 (Dec 2006): 1191–1214.https://doi.org/10.1134/S0016702906120044K. I. SHMULOVICH, B. W. D. YARDLEY, C. M. GRAHAM Solubility of quartz in crustal fluids: experiments and general equations for salt solutions and H2O-CO2 mixtures at 400-800oC and 0.1-0.9 GPa, Geofluids 6, no.22 (May 2006): 154–167.https://doi.org/10.1111/j.1468-8123.2006.00140.xRonald J. Bakker, J. Ben H. Jansen A mechanism for preferential H2O leakage from fluid inclusions in quartz, based on TEM observations, Contributions to Mineralogy and Petrology 116, no.1-21-2 (Mar 1994): 7–20.https://doi.org/10.1007/BF00310686John C. Ayers, E. Bruce Watson Rutile solubility and mobility in supercritical aqueous fluids, Contributions to Mineralogy and Petrology 114, no.33 (Jan 1993): 321–330.https://doi.org/10.1007/BF01046535S. E. Ziemniak Metal oxide solubility behavior in high temperature aqueous solutions, Journal of Solution Chemistry 21, no.88 (Aug 1992): 745–760.https://doi.org/10.1007/BF00651507David M. Jenkins Experimental study of the join tremolite-tschermakite: A reinvestigation, Contributions to Mineralogy and Petrology 99, no.33 (Jul 1988): 392–400.https://doi.org/10.1007/BF00375371Jean-Louis Dandurand, Jacques Schott New data on the solubility of amorphous silica in organic compound-water solutions and a new model for the thermodynamic behavior of aqueous silica in aqueous complex solutions, Journal of Solution Chemistry 16, no.33 (Mar 1987): 237–256.https://doi.org/10.1007/BF00646989M. S. Paterson The thermodynamics of water in quartz, Physics and Chemistry of Minerals 13, no.44 (Jul 1986): 245–255.https://doi.org/10.1007/BF00308276W. D. Gunter, H. P. Eugster Wollastonite solubility and free energy of supercritical aqueous CaCl2, Contributions to Mineralogy and Petrology 66, no.33 (Jan 1978): 271–281.https://doi.org/10.1007/BF00373411I-Ming Chou, Hans P. Eugster Fugacity control and dissociation constants of HBr and HI, Contributions to Mineralogy and Petrology 56, no.11 (Jan 1976): 77–100.https://doi.org/10.1007/BF00375422O. W. Flörke Transport and Deposition of SiO2 with H2O under Supercritical Conditions, Kristall und Technik 7, no.1-31-3 (Jan 1972): 159–166.https://doi.org/10.1002/crat.19720070117D. F. Weill, Y. Bottinga Thermodynamic analysis of quartz and cristobalite solubilities in water at saturation vapor pressure, Contributions to Mineralogy and Petrology 25, no.22 (Jan 1970): 125–132.https://doi.org/10.1007/BF00389780Günter Strübel Hydrothermale Lösungen, Geologische Rundschau 58, no.11 (Oct 1968): 259–273.https://doi.org/10.1007/BF01820607