The effect of Fe on olivine H2O storage capacity: Consequences for H2O in the martian mantle
-
A.C. Withers
,
M.M. Hirschmann
Abstract
To investigate the influence of chemical composition on the behavior of H2O in Fe-rich nominally anhydrous minerals, and to determine the difference between H2O behavior in the martian and terrestrial mantles, we conducted high-pressure H2O storage capacity experiments employing a wide range of olivine compositions. Experiments were conducted with bulk compositions in the system FeO-MgO-SiO2-H2O with Mg no. [Mg no. = 100 × molar Mg/(Mg+Fe)] ranging between 50 and 100 at 3 GPa in a piston-cylinder and at 6 GPa in a multi-anvil apparatus. Experiments at 3 GPa were conducted at 1200 °C, with fO₂ buffered by the coexistence of Fe and FeO, and at 1300-1500 °C in unbuffered assemblies. Experiments at 6 GPa were conducted at 1200 °C without buffers. Experiments at 1200 °C produced olivine+orthopyroxene+hydrous liquid (liq), and higher T experiments produced olivine+liq. Additionally, we synthesized a suite of 7 olivine standards (Mg no. = 90) for low blank secondary ion mass spectrometry (SIMS) analysis of H in multi-anvil experiments at 3-10 GPa and 1250 °C, resulting in large (200-400 μm) homogeneous crystals with 0.037 to 0.30 wt% H2O. Polarized Fourier transform infrared (FTIR) measurements on randomly oriented grains from the synthesis experiments were used to determine principal axis spectra through least-squares regression, and H contents were calculated from the total absorbance in the OH stretching region. Using these olivines as calibrants for SIMS analyses, the H contents of olivines and pyroxenes from the variable Mg no. experiments were measured by counting 16OH ions. Ignoring any matrix effects owing to variation in Mg no., H contents of olivine and pyroxene increase linearly with decreasing Mg no. At 6 GPa and 1200 °C, olivine H contents increase from 0.05 to 0.13 wt% H2O (8360 to 23 900 H/106 Si) as olivine Mg no. decreases from 100 to 68, and at 3 GPa and 1200 °C olivine H contents increase from 0.017 to 0.054 wt% (278 to 10 000 H/106 Si) as Mg no. decreases from 100 to 55. The partition coefficient for H between pyroxene and olivine, DHopx/ol, decreases from 1.05 at 3 GPa and 1200 °C to 0.61 at 6 GPa and 1200 °C. The storage capacity of Fe-rich olivines with compositions expected in the martian mantle is -1.5 times greater than those in the terrestrial mantle, suggesting that the geochemical behavior of H2O in the mantles of the two planets are quite similar. If 50% of the K2O on Mars remains in its mantle (Taylor et al. 2006), then a similar or greater proportion of the H2O is also in the mantle. Given accretionary models of the total martian H2O budget (Lunine et al. 2003), this suggests concentrations of 100-500 ppm H2O in the martian mantle and 0.1-1.9 wt% H2O in primary martian basalts.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Needs and opportunities in mineral evolution research
- Rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the Su-Lu UHP metamorphic belt in Donghai, East China
- A first-principles study of the phase transition from Holl-I to Holl-II in the composition KAlSi3O8
- Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement
- Thermoelastic and thermodynamic properties of plagioclase feldspars from thermal expansion measurements
- Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations
- In situ observation of the crystallization pressure induced by halite crystal growth in a microfluidic channel
- Microstructures of the larval shell of a pearl oyster, Pinctada fucata, investigated by FIB-TEM technique
- Magnesium quantification in calcites [(Ca,Mg)CO3] by Rietveld-based XRD analysis: Revisiting a well-established method
- The effect of Fe on olivine H2O storage capacity: Consequences for H2O in the martian mantle
- Kinetics of thermal transformation of partially dehydroxylated pyrophyllite
- Dehydration of the natural zeolite goosecreekite CaAl2Si6O16·5H2O upon stepwise heating: A single-crystal and powder X-ray study
- Incorporation mechanisms of Ta and Nb in zircon and implications for pegmatitic systems
- Variable-temperature 27Al and 29Si NMR studies of synthetic forsterite and Fe-bearing Dora Maira pyrope garnet: Temperature dependence and mechanisms of paramagnetically shifted peaks
- Calibrating Ti concentrations in quartz for SIMS determinations using NIST silicate glasses and application to the TitaniQ geothermobarometer
- Crystal structure of Na3Fe(SO4)3: A high-temperature product (∼400 °C) of sideronatrite [Na2Fe(SO4)2OH⋅3H2O]
- Evidence for boron incorporation into the serpentine crystal structure
- Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)
- Microtextures, microchemistry, and mineralogy of basaltic glass alteration, Jeju Island, Korea, with implications for elemental behavior
- Orientation of channel carbonate ions in apatite: Effect of pressure and composition
- Thermoelastic property and high-pressure stability of Fe7C3: Implication for iron-carbide in the Earth’s core
- Yttriaite-(Y): The natural occurrence of Y2O3 from the Bol’shaya Pol’ya River, Subpolar Urals, Russia
- Identification and characterization of nanosized tripuhyite in soil near Sb mine tailings
- Letter. High-pressure I2/c-P21/c phase transformation in SrAl2Si2O8 feldspar
- Letter. Crystal structure of uchucchacuaite, AgMnPb3Sb5S12, and its relationship with ramdohrite and fizélyite
Articles in the same Issue
- Needs and opportunities in mineral evolution research
- Rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the Su-Lu UHP metamorphic belt in Donghai, East China
- A first-principles study of the phase transition from Holl-I to Holl-II in the composition KAlSi3O8
- Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement
- Thermoelastic and thermodynamic properties of plagioclase feldspars from thermal expansion measurements
- Quantitative determination of chrysotile in massive serpentinites using DTA: Implications for asbestos determinations
- In situ observation of the crystallization pressure induced by halite crystal growth in a microfluidic channel
- Microstructures of the larval shell of a pearl oyster, Pinctada fucata, investigated by FIB-TEM technique
- Magnesium quantification in calcites [(Ca,Mg)CO3] by Rietveld-based XRD analysis: Revisiting a well-established method
- The effect of Fe on olivine H2O storage capacity: Consequences for H2O in the martian mantle
- Kinetics of thermal transformation of partially dehydroxylated pyrophyllite
- Dehydration of the natural zeolite goosecreekite CaAl2Si6O16·5H2O upon stepwise heating: A single-crystal and powder X-ray study
- Incorporation mechanisms of Ta and Nb in zircon and implications for pegmatitic systems
- Variable-temperature 27Al and 29Si NMR studies of synthetic forsterite and Fe-bearing Dora Maira pyrope garnet: Temperature dependence and mechanisms of paramagnetically shifted peaks
- Calibrating Ti concentrations in quartz for SIMS determinations using NIST silicate glasses and application to the TitaniQ geothermobarometer
- Crystal structure of Na3Fe(SO4)3: A high-temperature product (∼400 °C) of sideronatrite [Na2Fe(SO4)2OH⋅3H2O]
- Evidence for boron incorporation into the serpentine crystal structure
- Structure refinement of Ag-free heyrovskýite from Vulcano (Aeolian Islands, Italy)
- Microtextures, microchemistry, and mineralogy of basaltic glass alteration, Jeju Island, Korea, with implications for elemental behavior
- Orientation of channel carbonate ions in apatite: Effect of pressure and composition
- Thermoelastic property and high-pressure stability of Fe7C3: Implication for iron-carbide in the Earth’s core
- Yttriaite-(Y): The natural occurrence of Y2O3 from the Bol’shaya Pol’ya River, Subpolar Urals, Russia
- Identification and characterization of nanosized tripuhyite in soil near Sb mine tailings
- Letter. High-pressure I2/c-P21/c phase transformation in SrAl2Si2O8 feldspar
- Letter. Crystal structure of uchucchacuaite, AgMnPb3Sb5S12, and its relationship with ramdohrite and fizélyite
