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Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions

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Published/Copyright: April 23, 2014
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American Mineralogist
From the journal American Mineralogist Volume 99 Issue 4

Abstract

Speciation of D-O-H-C-N volatiles in alkali aluminosilicate melts and of silicate in D-O-H-C-N fluid has been determined in situ to 800 °C and >2 GPa under reducing and oxidizing conditions by using an externally heated hydrothermal diamond-anvil cell with Raman spectroscopy as the structural probe. Reducing conditions were near those of the IW oxygen buffer, whereas oxidizing conditions were obtained by conducting the experiments with oxidized components only and with Pt as a catalyst.

Raman bands assigned to C-H stretching in CHxDy isotopologues and CH4 groups (including CH3) were employed to determine the CH4/CHxDy ratio in fluids and melts. This ratio decreases from 1.5-2 at 500 °C to between 1.2 and 1 with 800 °C with ΔH-values of 13.6 ± 2.1 and 5.5 ± 1.1 kJ/mol for melt and fluid, respectively. The CH4/CHxDy fluid/melt partition coefficient ranges between ~16 and ~3 with ΔH = 33 ± 6 kJ/mol assuming no pressure effect. This behavior of deuterated and protonated complexes is ascribed to speciation of volatile and silicate components in fluids and melts in a manner that is conceptually similar to D/H partitioning among complexes and phases in brines and hydrous silicate systems.

Molecular N2 is the N-bearing species in fluids and melts under oxidizing conditions. Under reducing conditions, the dominant species are molecular NH3 and ammine groups, NH2-. The NH3/ NH2 ratio varies between 0.15 and 0.75 in the 425-800 °C temperature range. The enthalpy change of the ammonia/ammine equilibrium, ΔH, derived from the temperature and assuming no pressure effect on the equilibrium, is 19 ± 8 and 61 ± 9 kJ/mol for melt and fluid, respectively. The fluid/melt partition coefficient, (NH3 + NH2- )fluid/(NH3 + NH2- )melt, ranges from 8 to 3 with ΔH = 45 ± 12 kJ/mol. For oxidized nitrogen, the fluid/melt partition coefficient is twice or more of those values for reduced nitrogen. Hydrogen bonding can be detected at 500 °C and below. This behavior resembles that of H2O. Deuterium-containing analogues of the (N+H)-species could not be detected with precision because these were in the frequency-range of the second-order Raman shift of diamond in the diamond-anvil cell itself and could not be isolated from the strong background generated by the Raman intensity from the diamond. These results imply that, unlike noble gases, degassing of N-bearing species from the mantle is redox dependent, and is also more efficient at lower temperatures (shallow depths). Reduced and oxidized C-O-H-N species exist fluids and melts in the modern mantle, whereas reduced species dominated in the young Earth. The fH2-dependent speciation C-O-H-N volatile components result in fH2-dependent thermodynamic and transport properties of fluids and melts in the interior of the Earth and terrestrial planets. In fluids, the solubility of nominally incompatible trace elements can increase by orders of magnitude upon its saturation with silicate components. Trace element and stable isotope partitioning between fluids and melt can change by >100% for the same reason.

Keywords : Melt structure; volatiles; speciation; redox; isotope
Published Online: 2014-4-23
Published in Print: 2014-4-1

© 2014 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. New data on lunar magmatic processes
  2. Thermodynamic approach provides insights into the aging process of biological apatite
  3. Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
  4. Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
  5. Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
  6. Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
  7. Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
  8. Atomic structure and formation mechanism of (101) rutile twins from Diamantina (Brazil)
  9. Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate from Jáchymov, Czech Republic
  10. Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary
  11. Chemistry of bone mineral, based on the hypermineralized rostrum of the beaked whale Mesoplodon densirostris
  12. Allendeite (Sc4Zr3O12) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite
  13. Hutcheonite, Ca3Ti2(SiAl2)O12, a new garnet mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion
  14. Infrared absorption spectroscopy of SiO2-moganite
  15. Kaolinite transformation into dickite during burial diagenesis
  16. Effect of clays and metal containers in retaining Sm3+ and ZrO2+ and the process of reversibility
  17. Solid solutions and phase transitions in (Ca,M2+)M2+Si2O6 pyroxenes (M2+ = Co, Fe, Mg)
  18. Further complexities of the 10 Å phase revealed by infrared spectroscopy and X-ray diffraction
  19. Solid phases of FeSi to 47 GPa and 2800 K: New data
  20. In-situ infrared spectra of hydroxyl in wadsleyite and ringwoodite at high pressure and high temperature
  21. Experimental and infrared characterization of the miscibility gap along the tremoliteglaucophane join
  22. A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O
  23. Arsenate partitioning from ferrihydrite to hematite: Spectroscopic evidence
  24. Pressure-induced phase transitions in coesite
  25. Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
  26. Phase relations in the system FeCO3-CaCO3 at 6 GPa and 900–1700 °C and its relation to the system CaCO3-FeCO3-MgCO3
  27. In-situ high-temperature emissivity spectra and thermal expansion of C2/c pyroxenes: Implications for the surface of Mercury
  28. Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt
  29. Fluorowardite, NaAl3(PO4)2(OH)2F2·2H2O, the fluorine analog of wardite from the Silver Coin mine, Valmy, Nevada
  30. Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group mineral from the Cigana mine, Conselheiro Pena, Minas Gerais, Brazil
  31. Structural complexity of lead silicates: Crystal structure of Pb21[Si7O22]2[Si4O13] and its comparison to hyttsjöite
  32. A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
  33. Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
  34. Crystal chemistry of the ulvöspinel-qandilite series
  35. Quantitative models linking igneous amphibole composition with magma Cl and OH content
  36. Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
  37. New Mineral Names
  38. Errata
https://doi.org/10.2138/am.2014.4575
Keywords for this article
Melt structure; volatiles; speciation; redox; isotope

Articles in the same Issue

  1. New data on lunar magmatic processes
  2. Thermodynamic approach provides insights into the aging process of biological apatite
  3. Effects of chemical composition and temperature on transport properties of silica-rich glasses and melts
  4. Speciation of and D/H partitioning between fluids and melts in silicate-D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions
  5. Effect of oxalate and pH on chrysotile dissolution at 25 °C: An experimental study
  6. Gabbroic Shergottite Northwest Africa 6963: An intrusive sample of Mars
  7. Césarferreiraite, Fe2+Fe23+(AsO4)2(OH)2·8H2O, from Eduardo mine, Conselheiro Pena, Minas Gerais, Brazil: Second arsenate in the laueite mineral group
  8. Atomic structure and formation mechanism of (101) rutile twins from Diamantina (Brazil)
  9. Mathesiusite, K5(UO2)4(SO4)4(VO5)(H2O)4, a new uranyl vanadate-sulfate from Jáchymov, Czech Republic
  10. Comparison of metal enrichment in pyrite framboids from a metal-enriched and metal-poor estuary
  11. Chemistry of bone mineral, based on the hypermineralized rostrum of the beaked whale Mesoplodon densirostris
  12. Allendeite (Sc4Zr3O12) and hexamolybdenum (Mo,Ru,Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite
  13. Hutcheonite, Ca3Ti2(SiAl2)O12, a new garnet mineral from the Allende meteorite: An alteration phase in a Ca-Al-rich inclusion
  14. Infrared absorption spectroscopy of SiO2-moganite
  15. Kaolinite transformation into dickite during burial diagenesis
  16. Effect of clays and metal containers in retaining Sm3+ and ZrO2+ and the process of reversibility
  17. Solid solutions and phase transitions in (Ca,M2+)M2+Si2O6 pyroxenes (M2+ = Co, Fe, Mg)
  18. Further complexities of the 10 Å phase revealed by infrared spectroscopy and X-ray diffraction
  19. Solid phases of FeSi to 47 GPa and 2800 K: New data
  20. In-situ infrared spectra of hydroxyl in wadsleyite and ringwoodite at high pressure and high temperature
  21. Experimental and infrared characterization of the miscibility gap along the tremoliteglaucophane join
  22. A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O
  23. Arsenate partitioning from ferrihydrite to hematite: Spectroscopic evidence
  24. Pressure-induced phase transitions in coesite
  25. Qingsongite, natural cubic boron nitride: The first boron mineral from the Earth’s mantle
  26. Phase relations in the system FeCO3-CaCO3 at 6 GPa and 900–1700 °C and its relation to the system CaCO3-FeCO3-MgCO3
  27. In-situ high-temperature emissivity spectra and thermal expansion of C2/c pyroxenes: Implications for the surface of Mercury
  28. Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt
  29. Fluorowardite, NaAl3(PO4)2(OH)2F2·2H2O, the fluorine analog of wardite from the Silver Coin mine, Valmy, Nevada
  30. Correianevesite, Fe2+Mn22+(PO4)2·3H2O, a new reddingite-group mineral from the Cigana mine, Conselheiro Pena, Minas Gerais, Brazil
  31. Structural complexity of lead silicates: Crystal structure of Pb21[Si7O22]2[Si4O13] and its comparison to hyttsjöite
  32. A high-resolution powder neutron diffraction study of the crystal structure of neighborite (NaMgF3) between 9 and 440 K
  33. Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land (Antarctica)
  34. Crystal chemistry of the ulvöspinel-qandilite series
  35. Quantitative models linking igneous amphibole composition with magma Cl and OH content
  36. Chromium solubility in perovskite at high pressure: The structure of (Mg1–xCrx)(Si1–xCrx)O3 (with x = 0.07) synthesized at 23 GPa and 1600 °C
  37. New Mineral Names
  38. Errata
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