Experiments on the Saturation of Fluorite in Magmatic Systems: Implications for Maximum F Concentration and Fluorine-Cation Bonding in Silicate Melt

Abstract

The effects of melt composition, temperature and pressure on the solubility of fluorite (CaF₂), i.e., fluorine concentration in silicate melts in equilibrium with fluorite, are summarized in this paper. The authors present a statistic study based on experimental data in literature and propose a predictive model to estimate F concentration in melt at the saturation of fluorite (C _{F in melt} ^Fl-sat). The modeling indicates that the compositional effect of melt cations on the variation in C _{F in melt} ^Fl-sat can be expressed quantitatively as one parameter FSI (fluorite saturation index): FSI=(3Al^NM+Fe²⁺+6Mg+Ca+1.5Na-K)/(Si+Ti+Al^NF+Fe³⁺), in which all cations are in mole, and Al^NF and Al^NM are Al as network-forming and network-modifying cations, respectively. The dependence of C _{F in melt} ^Fl-sat on FSI is regressed as: C _{F in melt} ^Fl-sat=1.130−2.014·exp (1 000/T)+2.747·exp (P/T)+0.111·C _melt ^H2O +17.641·FSI, in which T is temperature in Kelvin, P is pressure in MPa, C _melt ^H2O is melt H₂O content in wt.%, and C _{F in melt} ^Fl-sat is in wt.% (normalized to anhydrous basis). The reference dataset used to establish the expression for conditions within 540–1 010 °C, 50–500 MPa, 0–7 wt.% melt H₂O content, 0.4 to 1.7 for A/CNK, 0.3 wt.%–7.0 wt.% for C _{F in melt} ^Fl-sat. The discrepancy of C _{F in melt} ^Fl-sat between calculated and measured values is less than ±0.62 wt.% with a confidence interval of 95%. The expression of FSI and its effect on C _{F in melt} ^Fl-sat indicate that fluorine incorporation in silicate melts is largely controlled by bonding with network-modifying cations, favorably with Mg, Al^NM, Na, Ca and Fe²⁺ in a decreasing order. The proposed model for predicting C _{F in melt} ^Fl-sat is also supported by our new experiments saturated with magmatic fluorite performed at 100–200 MPa and 800–900 °C. The modeling of magma fractional crystallization emphasizes that the saturation of fluorite is dependent on both the compositions of primary magmas and their initial F contents.

Keywords

fluorine / fluorite solubility / silicate melt / experimental petrology

References

Ahmed H A, Ma C Q, Wang L X, . Petrogenesis and Tectonic Implications of Peralkaline A-Type Granites and Syenites from the Suizhou-Zaoyang Region, Central China. Journal of Earth Science, 2018, 29(5): 1181-1202.

Aiuppa A, Baker D R, Webster J D. Halogens in Volcanic Systems. Chemical Geology, 2009, 263(1/2/3/4): 1-18.

Aseri A A, Linnen R L, Che X D, . Effects of Fluorine on the Solubilities of Nb, Ta, Zr and Hf Minerals in Highly Fluxed Water-Saturated Haplogranitic Melts. Ore Geology Reviews, 2015, 64: 736-746.

Baasner A, Schmidt B C, Dupree R, . Fluorine Speciation as a Function of Composition in Peralkaline and Peraluminous Na₂O-CaO-Al₂O₃ ⁻SiO₂ Glasses: A Multinuclear NMR Study. Geochimica et Cosmochimica Acta, 2014, 132: 151-169.

Baasner A, Schmidt B C, Webb S L. The Effect of Chlorine, Fluorine and Water on the Viscosity of Aluminosilicate Melts. Chemical Geology, 2013, 357: 134-149.

Badanina E V, Trumbull R B, Dulski P, . The Behavior of Rare-Earth and Lithophile Trace Elements in Rare-Metal Granites: A Study of Fluorite, Melt Inclusions and Host Rocks from the Khangilay Complex, Transbaikalia, Russia. The Canadian Mineralogist, 2006, 44(3): 667-692.

Bailey J C. Fluorine in Granitic Rocks and Melts: A Review. Chemical Geology, 1977, 19(1/2/3/4): 1-42.

Baker D R, Vaillancourt J. The Low Viscosities of F+H₂O-Bearing Granitic Melts and Implications for Melt Extraction and Transport. Earth and Planetary Science Letters, 1995, 132(1/2/3/4): 199-211.

Bao B, Webster J D, Zhang D H, . Compositions of Biotite, Amphibole, Apatite and Silicate Melt Inclusions from the Tongchang Mine, Dexing Porphyry Deposit, SE China: Implications for the Behavior of Halogens in Mineralized Porphyry Systems. Ore Geology Reviews, 2016, 79: 443-462.

Bartels A, Behrens H, Holtz F, . The Effect of Fluorine, Boron and Phosphorus on the Viscosity of Pegmatite Forming Melts. Chemical Geology, 2013, 346: 184-198.

Berndt J, Liebske C, Holtz F, . A Combined Rapid-Quench and H₂-Membrane Setup for Internally Heated Pressure Vessels: Description and Application for Water Solubility in Basaltic Melts. American Mineralogist, 2002, 87(11/12): 1717-1726.

Botcharnikov R E, Holtz F, Almeev R R, . Storage Conditions and Evolution of Andesitic Magma Prior to the 1991–95 Eruption of Unzen Volcano: Constraints from Natural Samples and Phase Equilibria Experiments. Journal of Volcanology and Geothermal Research, 2008, 175(1/2): 168-180.

Chelle-Michou C, Chiaradia M. Amphibole and Apatite Insights into the Evolution and Mass Balance of Cl and S in Magmas Associated with Porphyry Copper Deposits. Contributions to Mineralogy and Petrology, 2017, 172(11/12): 105

Chevychelov V Y, Botcharnikov R E, Holtz F. Experimental Study of Fluorine and Chlorine Contents in Mica (Biotite) and Their Partitioning between Mica, Phonolite Melt, and Fluid. Geochemistry International, 2008, 46 11 1081-1089.

Dalou C L, Le Losq C, Mysen B O, . Solubility and Solution Mechanisms of Chlorine and Fluorine in Aluminosilicate Melts at High Pressure and High Temperature. American Mineralogist, 2015, 100(10): 2272-2283.

Dingwell D B, Mysen B O. Effects of Water and Fluorine on the Viscosity of Albite Melt at High Pressure: A Preliminary Investigation. Earth and Planetary Science Letters, 1985, 74(2/3): 266-274.

Doherty A L, Webster J D, Goldoff B A, . Partitioning Behavior of Chlorine and Fluorine in Felsic Melt-Fluid(s)-Apatite Systems at 50 MPa and 850–950 °C. Chemical Geology, 2014, 384: 94-111.

Dolejš D, Baker D R. Fluorite Solubility in Hydrous Haplogranitic Melts at 100 MPa. Chemical Geology, 2006, 225(1/2): 40-60.

Gabitov R I, Price J D, Watson E B. Solubility of Fluorite in Haplogranitic Melt of Variable Alkalis and Alumina Content at 800–1 000 °C and 100 MPa. Geochemistry, Geophysics, Geosystems, 2005, 6(3): Q03007

Giesting P A, Filiberto J. Quantitative Models Linking Igneous Amphibole Composition with Magma Cl and OH Content. American Mineralogist, 2014, 99 4 852-865.

Gualda G A R, Ghiorso M S, Lemons R V, . Rhyolite-MELTS: A Modified Calibration of MELTS Optimized for Silica-Rich, Fluid-Bearing Magmatic Systems. Journal of Petrology, 2012, 53(5): 875-890.

Holtz F, Sato H, Lewis J, . Experimental Petrology of the 1991–1995 Unzen Dacite, Japan. Part I: Phase Relations, Phase Composition and Pre-Eruptive Conditions. Journal of Petrology, 2005, 46(2): 319-337.

Hou T, Charlier B, Namur O, . Experimental Study of Liquid Immiscibility in the Kiruna-Type Vergenoeg Iron-Fluorine Deposit, South Africa. Geochimica et Cosmochimica Acta, 2017, 203: 303-322.

Huang H, Wang T, Zhang Z C, . Highly Differentiated Fluorine-Rich, Alkaline Granitic Magma Linked to Rare Metal Mineralization: A Case Study from the Boziguo’er Rare Metal Granitic Pluton in South Tianshan Terrane, Xinjiang, NW China. Ore Geology Reviews, 2018, 96: 146-163.

Icenhower J P, London D. Partitioning of Fluorine and Chlorine between Biotite and Granitic Melt: Experimental Calibration at 200 MPa H₂O. Contributions to Mineralogy and Petrology, 1997, 127(1/2): 17-29.

Iveson A A, Webster J D, Rowe M C, . Major Element and Halogen (F, Cl) Mineral-Melt-Fluid Partitioning in Hydrous Rhyodacitic Melts at Shallow Crustal Conditions. Journal of Petrology, 2017, 58(12): 2465-2492.

Jiang W C, Li H, Wu J H, . A Newly Found Biotite Syenogranite in the Huangshaping Polymetallic Deposit, South China: Insights into Cu Mineralization. Journal of Earth Science, 2018, 29(3): 537-555.

Keppler H. Influence of Fluorine on the Enrichment of High Field Strength Trace Elements in Granitic Rocks. Contributions to Mineralogy and Petrology, 1993, 114(4): 479-488.

Keppler H, Wyllie P J. Partitioning of Cu, Sn, Mo, W, U, and Th between Melt and Aqueous Fluid in the Systems Haplogranite-H₂O-HCl and Haplogranite-H₂O-HF. Contributions to Mineralogy and Petrology, 1991, 109(2): 139-150.

Kohn S, Dupree R, Mortuza M, . NMR Evidence for Five- and Six-Coordinated Aluminum Fluoride Complexes in F-Bearing Aluminosilicate Glasses. American Mineralogist, 1991, 76(1/2): 309-312

Kress V C, Carmichael I S E. The Compressibility of Silicate Liquids Containing Fe₂O₃ and the Effect of Composition, Temperature, Oxygen Fugacity and Pressure on Their Redox States. Contributions to Mineralogy and Petrology, 1991, 108(1/2): 82-92.

Li H J, Hermann J. Apatite as an Indicator of Fluid Salinity: An Experimental Study of Chlorine and Fluorine Partitioning in Subducted Sediments. Geochimica et Cosmochimica Acta, 2015, 166: 267-297.

Li X Y, Zhang C, Behrens H, . Fluorine Partitioning between Titanite and Silicate Melt and Its Dependence on Melt Composition: Experiments at 50–200 MPa and 875–925 °C. European Journal of Mineralogy, 2018, 30(1): 33-44.

Lukkari S, Holtz F. Phase Relations of a F-Enriched Peraluminous Granite: An Experimental Study of the Kymi Topaz Granite Stock, Southern Finland. Contributions to Mineralogy and Petrology, 2007, 153(3): 273-288.

Manning D A C. The Effect of Fluorine on Liquidus Phase Relationships in the System Qz-Ab-Or with Excess Water at 1 kb. Contributions to Mineralogy and Petrology, 1981, 76(2): 206-215.

Mathez E A, Webster J D. Partitioning Behavior of Chlorine and Fluorine in the System Apatite-Silicate Melt-Fluid. Geochimica et Cosmochimica Acta, 2005, 69(5): 1275-1286.

McCubbin F M, Vander Kaaden K E, Tartèse R, . Experimental Investigation of F, Cl, and OH Partitioning between Apatite and Fe-Rich Basaltic Melt at 1.0–1.2 GPa and 950–1 000 °C. American Mineralogist, 2015, 100(8/9): 1790-1802.

Mysen B O, Cody G D, Smith A. Solubility Mechanisms of Fluorine in Peralkaline and Meta-Aluminous Silicate Glasses and in Melts to Magmatic Temperatures. Geochimica et Cosmochimica Acta, 2004, 68(12): 2745-2769.

Pichavant M, Manning D. Petrogenesis of Tourmaline Granites and Topaz Granites; The Contribution of Experimental Data. Physics of the Earth and Planetary Interiors, 1984, 35(1/2/3): 31-50.

Price J D, Hogan J P, Gilbert M C, . Experimental Study of Titanite-Fluorite Equilibria in the A-Type Mount Scott Granite: Implications for Assessing F Contents of Felsic Magma. Geology, 1999, 27(10): 951-954.

Scaillet B, Macdonald R. Experimental Constraints on the Relationships between Peralkaline Rhyolites of the Kenya Rift Valley. Journal of Petrology, 2003, 44(10): 1867-1894.

Scaillet B, Macdonald R. Fluorite Stability in Silicic Magmas. Contributions to Mineralogy and Petrology, 2004, 147(3): 319-329.

Schwab R, Küstner D. The Equilibrium Fugacities of Important Oxygen Buffers in Technology and Petrology. Neues Jahrbuch für Mineralogie, 1981, 140: 112-142.

Stebbins J F, Zeng Q. Cation Ordering at Fluoride Sites in Silicate Glasses: A High-Resolution 19F NMR Study. Journal of Non-Crystalline Solids, 2000, 262(1/2/3): 1-5

Tossell J. Theoretical Studies of the Speciation of Al in F-Bearing Aluminosilicate Glasses. American Mineralogist, 1993, 78(1/2): 16-22

Van den Bleeken G, Koga K T. Experimentally Determined Distribution of Fluorine and Chlorine Upon Hydrous Slab Melting, and Implications for F-Cl Cycling through Subduction Zones. Geochimica et Cosmochimica Acta, 2015, 171: 353-373.

Veksler I V, Dorfman A M, Kamenetsky M, . Partitioning of Lanthanides and Y between Immiscible Silicate and Fluoride Melts, Fluorite and Cryolite and the Origin of the Lanthanide Tetrad Effect in Igneous Rocks. Geochimica et Cosmochimica Acta, 2005, 69(11): 2847-2860.

Veksler I V, Thomas R, Schmidt C. Experimental Evidence of Three Coexisting Immiscible Fluids in Synthetic Granitic Pegmatite. American Mineralogist, 2002, 87(5/6): 775-779.

Wang L X, Ma C Q, Zhang C, . Halogen Geochemistry of I- and A-Type Granites from Jiuhuashan Region (South China): Insights into the Elevated Fluorine in A-Type Granite. Chemical Geology, 2018, 478: 164-182.

Wang L X, Marks M A W, Wenzel T, . Halogen-Bearing Minerals from the Tamazeght Complex (Morocco): Constraints on Halogen Distribution and Evolution in Alkaline to Peralkaline Magmatic Systems. The Canadian Mineralogist, 2016, 54(6): 1347-1368.

Webster J D, Goldoff B A, Flesch R N, . Hydroxyl, Cl, and F Partitioning between High-Silica Rhyolitic Melts-Apatite-Fluid(s) at 50–200 MPa and 700–1 000 °C. American Mineralogist, 2017, 102(1): 61-74.

Webster J D, Tappen C M, Mandeville C W. Partitioning Behavior of Chlorine and Fluorine in the System Apatite-Melt-Fluid. II: Felsic Silicate Systems at 200 MPa. Geochimica et Cosmochimica Acta, 2009, 73(3): 559-581.

Wengorsch T. Experimental Constraints on the Storage Conditions of a Tephriphonolite from the Cumbre Vieja Volcano (La Palma, Canary Islands) at 200 and 400 MPa: [Dissertation], 2013, Hannover: Leibniz Universität Hannover, 97

Xiong X L, Rao B, Chen F R, . Crystallization and Melting Experiments of a Fluorine-Rich Leucogranite from the Xianghualing Pluton, South China, at 150 MPa and H₂O-Saturated Conditions. Journal of Asian Earth Sciences, 2002, 21(2): 175-188.

Zeng Q, Stebbins J F. Fluoride Sites in Aluminosilicate Glasses: High-Resolution19F NMR Results. American Mineralogist, 2000, 85(5/6): 863-867.

Zhang C, Holtz F, Ma C Q, . Tracing the Evolution and Distribution of F and Cl in Plutonic Systems from Volatile-Bearing Minerals: A Case Study from the Liujiawa Pluton (Dabie Orogen, China). Contributions to Mineralogy and Petrology, 2012, 164(5): 859-879.

Zhang C, Koepke J, Albrecht M, . Apatite in the Dike-Gabbro Transition Zone of Mid-Ocean Ridge: Evidence for Brine Assimilation by Axial Melt Lens. American Mineralogist, 2017, 102(3): 558-570.

Zhang C, Koepke J, Wang L X, . A Practical Method for Accurate Measurement of Trace Level Fluorine in Mg- and Fe-Bearing Minerals and Glasses Using Electron Probe Microanalysis. Geostandards and Geoanalytical Research, 2016, 40(3): 351-363.