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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

The role of P2O5 in silicate melts

Phase equilibria data in the systems SiO2-P2O5, P2O5-M(x)O(y), and P2O5-M(x)O(y)-SiO2 are employed in conjunction with chromatographic and spectral data to investigate the role of P2O5 in silicate melts. P2O5 depolymerizes pure SiO2 melts by entering the network as a four-fold coordinated cation, but polymerizes melts in which an additional metal cation other than silicon is present. In this complex system P2O5 acts to increase phase separation by further enrichment of the high charge density cations Ti, Fe, Mg, Mn, Ca, in the ferrobasaltic liquid. The dual behavior of P2O5 is explained in a model which requires complexing of phosphate anions and metal cations in the melt. This interaction destroys Si-O-M-O-Si bonds polymerizing the melt. The higher concentration of Si-O-M-O-Si bond complexes in immiscible ferrobasaltic liquids relative to their conjugate immiscible granite liquids explains the partitioning of P2O5 into the ferrobasaltic liquid.

Ryerson, F. J.↗
NASA NTRS1980

Cl, P2O5, U and Br associated with mineral separates from a low and a high Ti mare basalt

Low Ti basalt 12040 and high Ti basalt 75055 have approximately the same Cl/P2O5 ratio; the Cl is that remaining after a hot water leach. Pyroxene, plagioclase and ilmenite minerals separated from the basalts also tend to have this same Cl/P2O5 ratio. This is evidence that these major minerals do not control the ratio since Cl and P would not be expected to partition to the same extent into each mineral. Olivine appears to be a special case. It is proposed that the grains measured contained inclusions with leachable and P2O5-related Cl. Dilute acid leaches of whole rock and separated minerals have the same or nearly the same Cl/P2O5 ratios as the residual samples. Apatite and whitlockite were probably the phases leached. They must be constituents of the mesostasis and are present as microminerals or coatings on major mineral grains. The acid leach results imply little or no partition of Cl and P2O5 into major minerals.

Jovanovic, S.↗
NASA NTRS1975

Electrical resistivity surface for FeO-Fe2O3-P2O5 glasses

The dc electrical properties and microstructure of x(FeO-Fe2O3)-(100-x)P2O5 glasses were investigated up to a maximum of x = 75 mol %. Results indicate that, in general, the minimum resistivity of the glass does not occur at equal Fe(2+) and Fe(3+) concentrations, although for the special case where x = 55 mol % the minimum does occur at Fe(2+)/Fe total = 0.5, as reported by other investigators. Evidence presented shows that the position of the minimum resistivity is a function of total iron content. The minimum shifts to glasses richer in Fe(2+) at higher total iron concentrations.

Vaughan, J. G.↗
NASA NTRS1993

Partitioning of Nb, Mo, Ba, Ce, Pb, Th and U between immiscible carbonate and silicate liquids: Evaluating the effects of P2O5,F, and carbonate composition

Previously we have reported carbonate liq./silicate liq. partition coefficients (D) for a standard suite of trace elements (Nb, Mo, Ba, Ce, Pb, Th, and U) and Ra and Pa as well. In brief, we have found that immiscible liquid partitioning is a strong function of temperature. As the critical temperature of the carbonate-silicate solvus is approached, all partition coefficients approach unity. Additionally, for the overwhelming majority of the partitioning elements, InD is a linear function of 'ionic field strength,' z/r, where z is the charge of the partitioned cation and r is its ionic radius.

Jones, J. H.↗
NASA NTRS2002

Phosphorus Equilibria Among Mafic Silicate Phases

Phosphorus incorporation in major rock-forming silicate minerals has the following implications: (1) Reactions between phosphorus-hosting major silicates and accessory phosphates, which are also major trace element carriers, may control the stability of the latter and thus may affect the amount of phosphorus and other trace elements released to the coexisting melt or fluid phase. (2) Less of a phosphate mineral is needed to account for the bulk phosphorus of planetaty mantles. (3) During partial melting of mantle mineral assemblages or equilibrium fractional crystallization of basaltic magmas, and in the absence or prior to saturation with a phosphate mineral, silicate melts may become enriched in phosphorus, especially in the geochemically important low melt fraction regime, Although the small differences in the ionic radii of IVp5+, IVSi4+, and IV Al3+ makes phosphoms incorporation into crystalline silicates perhaps unsurprising, isostructural silicate and phosphate crystalline solids do not readily form solutions, e.g., (Fe, Mg)2SiO4 vs. LiMgPO4, SiO)2 VS. AlPO4. Nonetheless, there are reports of, poorly characterized silico-phosphate phases in angrites , 2-4 wt% P2O5 in olivine and pyroxene grains in pallasites and reduced terestrial basalts which are little understood but potentially useful, and up to 17 wt% P2O5 in olivine from ancient slags. However, such enrichments are rare and only underscore the likelihood of phosphoms incorporation in silicate minerals. The mechanisms that allow phosphorus to enter major rock-forming silicate minerals (e.g., Oliv, Px, Gt) remain little understood and the relevant data base is limited. Nonetheless, old and new high-pressure (5-10 GPa) experimental data suggest that P2O5 wt% decreases from silica-poor to silica-rich compositions or from orthosilicate to chain silicate structures (garnet > olivine > orthopyroxene) which implies that phosphorus incorporation in silicates is perhaps more structure-than site-specific. The data also indicate that DXVliQP2O5 decrease in the same order, but DOVLiQP2O5 and DOpx/LiQP205 are likely constant, respectively equal to 0.08(3) and 0.007(4), in contrast, DG1ILiQP205 increases from 0.15(3) to 0.36(10) as garnet becomes majoritic, thus silica-enriched, and may also depend on liquid composition (SiO2, P2O5 and Na2O wt%).

Berlin, Jana↗
NASA NTRSDate not supplied

Importance of Sulfur for Phosphorus Mobility on the Martian Surface

Sulfur and phosphorus were mobile on the martian surface, and we present evidence that sulfate was likely a control on phosphate mobility. Mobility of the two elements on the martian surface is crucial for the habitability of Mars because their availability for biochemical reactions and biological structures is a major constraint on life. In the sedimentary rocks of Gale crater, the rover Curiosity has discovered evidence of mobile S and P with the alpha particle X-ray spectrometer (APXS). Sulfur-rich fluids are evident in ubiquitous Ca-sulfate veins that crosscut the bedrock. Compelling evidence of P mobility is in nodules, veins, crusts, and haloes with P2O5 enrichments (1.5-7.5 wt%) relative to the median bedrock (0.9-1.2 wt%) and average basaltic crust (~0.9 wt%). We have investigated phosphorus mobility in Hawaiian analogues, where the primary P2O5 (0.2-2.1 wt%) is contained in Ca-apatite. Four relevant processes have emerged: (1) In open-system, circumneutral regolith weathering profiles, we found up to 40% of the P was leached over 10s-100s ka. (2) Natural acid-sulfate alteration at the Maunakea summit resulted in the dissolution of apatite and mobilization of phosphate 10s-1000s µm to rock surfaces where it formed Al-phosphates and substituted into crystalline sulfates (alunite and jarosite). (3) Experimental results indicate that basaltic sediment chemisorbs phosphate (pH < 7). (4) In experimental systems containing water, basaltic sediment, and a starting pH = 2-7, phosphate has higher solubility in chloride-rich fluids, but significantly lower solubility in sulfate-rich fluids. For example, in water doped with phosphate (~100-500 mg/L), ~60-80% of the PO43- was removed from the sulfate-rich fluid, whereas ~20% of the PO43- was removed from the Cl-rich and pure water fluids (likely via adsorption). Gypsum precipitated from the sulfate-rich fluids; the fate of phosphate in the solid residue is unconfirmed. The potential for phosphate incorporation in martian sulfates is reflected in the enrichment of P2O5 in Gale Ca-sulfate veins, based on preliminary analyses of APXS data. Models for the mobility of phosphorus in Gale crater should consider these conflicting P characteristics: (1) P solubility may have been inhibited by sulfate and (2) P¬ is enriched in diagenetic features and was therefore mobile.

Jeff A. Berger↗
NASA NTRS1976

Convection cells in the early lunar magma ocean - Trace-element evidence

A method was proposed for recognizing suites of samples which are related to the differentiation of distinct and regionally separated magmas in the early lunar surface ocean. The sample suites were identified by three Cl-P2O5 compositional groups. New experimental data continue to add samples to these groups. Each magma was associated with a convection cell the boundaries of which are proposed. Independent geochemical evidence supporting a limited number of early magmas is cited. Two new possible Cl-P2O5 groups are identified. Samples not indigenous to a given site and their possible source regions are identified. It is proposed that many Apollo 17 basalts are not locally derived.

Jovanovic, S.↗
NASA NTRS1982

The significance of Cl/P2O5 ratios from lunar samples

The Cl(r)/P2O5 ratios of lunar samples are reported to occur in three groups (Jovanovic and Reed, 1975; etc.). These data have been modeled as representative of three discrete volumes of differentiating magma and correlated with large convection cells and moon-wide heterogeneities. The assumptions inherent to their model are not valid. That the Cl(r)/P2O5 ratio of apatite or a rock is indicative of a magma system is unrealistic. A range of ratios can be generated during the fractionation of a magma. Apatite is not the major Cl- and P-bearing phase in most of the samples analyzed; rust, FeO(OH, Cl) and schreibersite, (FeNi)3P, occur in over 2/3 rds of the Apollo 16 rocks where they constitute 0.1-0.6 modal %, enough to account for most of the Cl(r) and P2O5 analyzed. Due to the complexities and presence of these minerals in soils and breccias, Cl(r)/P2O5 ratios have no real significance in non-igneous samples. However, basaltic rocks alone do not define any statistically significant Cl(r)P2O5 groupings.

Taylor, L. A.↗
NASA NTRS1984

Achondrite ALHA77005 - Alteration of chromite and olivine

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration.

Smith, J. V.↗
NASA NTRS1986

Dependence of the critical cooling rate for lithium-silicate glass on nucleating agents

The critical cooling rate, Rc, for glass formation of a glass containing 40 mol pct Li2O and 60 mol pct SiO2, doped with small amounts of Pt, Au, P2O5, and TiO2 nucleating agents, has been measured. Rc increases with increasing Pt and Au additions, but Pt has a larger effect than Au. Additions of P2O5 tend to decrease Rc, whereas TiO2 has practically no effect on Rc. The devitrified glass nucleated with Pt contains only crystalline Li2O-SiO2, but all the other devitrified glasses, including the undoped glass, contain both Li2O-SiO2 and Li2O-2SiO2. Analysis shows that Rc increases as the concentration of the Li2O-SiO2 phase in the devitrified glass increases.

Huang, W.↗
NASA NTRS1971

A dunite-norite lunar microbreccia.

An olivine-rich microbreccia with noritic affinities, collected on the Apollo 14 mission to Fra Mauro, is described and analyzed. A photomicrograph (by plain transmitted light) of the microbreccia is discussed. One of three distinct areas on the microbreccia is shown to be a dunite containing over 90% olivine. The other two are more gabbroic in composition, though most of the mineral clasts are olivine. The fine grained matrix material contains significant amounts of K2O and P2O5, suggesting a relation to norites.

Taylor, G. J.↗
NASA NTRS1972

Effects of vaporization and condensation on Apollo 11 glass spherules - Implications for cooling rates.

Fourteen of 40 glass spherules present in a section of the Apollo 11 microbreccia 10019,22 were found to exhibit steep concentration gradients at their rims; the oxides of the relatively volatile elements Na, K, and P increase by, respectively, factors of up to 67, 16, and greater than 54 at the spherule rims in comparison to the homogeneous centers. These gradients usually extend over 25-30 microns. Furthermore, the natural surfaces of 11 unpolished glass spherules separated from the fines 10084,97, in 60-80% of all cases, show higher concentrations in Na2O, K2O, and P2O5 than the averages for the central portions of 45 independently analyzed glass spherules. It is suggested that the concentration gradients observed are diffusion gradients and are the result of the impact event which produced the glasses; in the impact melting process, splash drops of melt formed that lost volatiles by vaporization. A procedure is described to determine the cooling rate of a spherule from measured concentration gradients, provided the diffusion coefficients are known for the particular glass compositions in question.

Kurat, G.↗
NASA NTRS1973

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components

The thermal inactivation curve for Bacillus subtilis var. niger spores on the Viking lander is examined. Tests were conducted at 113 C and 25% RH, and over a wide range of temperatures using .001% RH and additions of P2O5 to dry the environment. Results show the 25% RH environment did not significantly reduce the survival curve, while the survival curves for spores treated under the drier .001% RH environment was reduced by a factor of 3.

Campbell, J. E.↗
NASA NTRS1972

The Oro Grande, New Mexico, chondrite and its lithic inclusion.

The Oro Grande, New Mexico, U.S.A., chondrite was found in 1971. Electron microprobe analyses and microscopic examination show the following mineralogy: olivine (Fa 19.3 mole %), orthopyroxene (Fs 16.2 mole %), diopside, feldspar (An 13.6 mole %), chlorapatite, whitlockite, kamacite, taenite, troilite, chromite, and an iron-bearing terrestrial weathering product. A bulk chemical analysis of the meteorite shows the following results (weight %): Fe 0.84, Ni 1.46, Co 0.07, FeS 3.62, SiO2 34.18, TiO2 0.14, Al2O3 1.83, Cr2O3 0.55, Fe2O3 21.25, FeO 9.13, MnO 0.31, MgO 21.52, CaO 1.72, Na2O 0.70, K2O 0.08, P2O5 0.25, H2O(+) 2.14, H2O(-) 0.40, C 0.22, sum 100.41. On the basis of composition and texture the Oro Grande meteorite is classified as an H5 chondrite.

Fodor, R. V.↗
NASA NTRS1973

Volatile trace elements and the characterization of the Cayley Formation and the primitive lunar crust

Two types of highland terrain appear to be present at the Apollo 16 landing site. The Plains Formation called Cayley is ubiquitous and blankets even those regions that were presumably a part of the mountainous Descartes Formation. The second type of terrain is that associated with the ejectae from North and South Ray craters. The stratigraphy sampled by the ejectae underlays the Cayley layer as characterized above and may permit a redefinition of Descartes Formation as that which underlays the smooth Plains deposits. These conclusions are based on the concentrations and chemical coherence between elements such as Cl-F-P2O5 and Ru-Os. The primitive lunar crust may be characterized by the type of feldspathic rocks which are enriched in trace elements, such as Cl, Br, U, Te, Ru, and Os, as found in 'rusty' rock 66095 and in 61016; other feldspathic rocks are depleted and may be of secondary origin.

Jovanovic, S.↗
NASA NTRS1974

Regolith compositions from the Apollo 17 mission

An investigation of the chemical, mineralogical, and petrographic data from six Apollo 17 regolith samples is summarized. The samples from the center of the Taurus-Littrow valley are very similar in composition and consist of mare basalt and a minor admixture (about 25%) of plagioclase-rich material. The material from Station 9 (Van Serg Crater) contains much less basalt and more breccia and are higher in Al2O3 and lower in TiO2 and FeO than the other mare sites. The chemical compositions of the samples from the North Massif, the South Massif, and the light mantle believed to be of landslide origin, are very similar and correspond to an olivine norite; the relatively high K2O and P2O5 content indicate the presence of a KREEP component. Additional results are described in detail.

Mason, B.↗
NASA NTRS1974

Labile and nonlabile element relationships among Apollo 17 samples

Volatile and nonvolatile trace element contents in a suite of Apollo 17 soils and rocks are studied. It is found that the halogens exhibit a remarkable degree of coherence because of their apparent diverse geochemistry, that the F-Cl-P2O5 coherence previously noted persists among Apollo 17 samples, that both U and Ru-Os support lateral mixing of regolith on a local scale, and that the meteoritic Ru/Os ratios found in a few samples are attributed to primitive lunar material that has not been extensively recycled.

Jovanovic, S.↗
NASA NTRS1975

History of Boulder 1 at Station 2, Apollo 17 based on trace element interrelationships

Correlations among the trace and minor element pairs Cl and Br, Cl and P2O5, and Ru and Os, present in parent igneous rocks, generally survived the processes of boulder breccia formation. Fractions of Cl, Br, and Hg that are mobilized by water leaching or volatilization at moderate temperatures place constraints on the thermal history of Boulder 1 and its component breccias. Since, and possibly during, consolidation, the boulder has probably not been subjected to temperatures in excess of 450 C. The parent rocks of the Apollo 17 boulder and breccia samples studied could have been derived from two initial magmas. Vapor clouds from apparently external sources permeated the source regions of the boulders.

Jovanovic, S.↗