45 research outputs found
Data for: The potential of phosphorus in clinopyroxene as a geospeedometer: examples from mantle xenoliths
No full textThis is a dataset related with the paper: The potential of phosphorus in clinopyroxene as a geospeedometer: examples from mantle xenoliths. In table S1 processed electron probe data are included. The data for each mineral are provided in separate tabs. In table S2, laser ablation data (for Cima Volcanic Field-Ci-1-105a and Moroccan-MA1 xenoliths), along with glasses are given
Phosphorus-rich pyroxene in mantle xenoliths
No full textNumerous recent reports of detailed crystal zoning
patterns and anomalous enrichment in phosphorus (P) have
focused mainly on olivine from various settings [1-4]. P
enrichment and zoning in olivine have been attributed to
rapid crystal growth and development of disequilibrium as
well as to growth from P-rich melts. Here we report the
comparatively novel observation of elevated P in pyroxenes
from glass-bearing veins and pockets in a previously
undescribed xenolith from Cima Volcanic Field-CVF,
California; H.G. Wilshire (sample Ci-1-105) and in newly
collected mantle xenoliths from the Middle Atlas, Morocco.
Analytical techniques included optical microscopy, electron
microprobe and laser-ablation Inductively Coupled Plasma
Mass Spectrometry. We examine whether the P
concentrations in pyroxene (Px), although unusual, are in fact
anomalous compared to the adjacent glass concentration,
consider possible mechanisms for P enrichment, and correlate
the P enrichment in Px with indicators of metasomatism.
The petrogenetic history of each glassy region involves
melt intrusion, reaction with host minerals, cooling
accompanied by crystal growth, quench of glass, and possibly
later modifications. Secondary P-rich pyroxenes (P2O5 ~ 0.6
wt%) in a glassy pocket in the CVF xenolith are
homogeneous and surrounded by P-rich glass. They reflect
fairly slow near-equilibrium pyroxene growth after the melt
temperature became close to the host rock, with P
concentration in the melt buffered by apatite saturation. In the
Moroccan xenoliths, pyroxenes in a glassy vein exhibit
concentric zoning with P2O5 from 0.05 wt% (core) to ca. 0.3
wt% (intermediate) and then from 0.8 wt% (inner rim) to 1.2
wt% (outer rim). We attribute this to an accelerating rate of
crystal growth, with onset of a diffusive boundary layer pileup
effect and excess P incorporation near the pyroxene rim
Interactions of Real Urine with Modified Palygorskite and Zeolite Focusing on Adsorption Mechanisms, Nutrient Bioavailability and Soil Conditioner Upgrade
No full textNutrient recovery from urine can contribute to sustainable crop production. However, the efficient
reuse of adsorbed nutrients depends on their bioavailability, a characteristic that is typically disregarded. In this
study, Ca(OH)2-treated zeolite (CaT-Zeol) and palygorskite (CaT-Pal) were compared as one-time adsorbents of
PO4-P and NH4-N in aqueous solutions and real human urine. Desorption tests were conducted to determine the
real solid concentration of nutrients after adsorption in fresh (FU) and hydrolyzed urine (HU). They revealed that (i) CaT-Zeol immobilized more P (6.27–6.79 mg/g) than CaT-Pal (5.35–5.68 mg/g), and (ii) drying the loaded adsorbents at 35 or 105 °C slightly affected the total P desorption. Both materials adsorbed less P from the alkaline HU (1.92 mg/g CaT-Zeol and 0.50 mg/g CaT-Pal) than from the slightly acidic FU. The calcium bound P predominated on the FU-loaded adsorbents, followed by the plant-available NaHCO3-P. Compared to the CaT-Pal (0.09–0.61 mg N/g), the desorption of plantavailable NH4 N from the FU- and HU-loaded CaT-Zeol (1.72–8.07 mg N/g) was significantly higher. SEM–EDS analyses confirmed the formation of calcium phosphate phases on the FU-loaded adsorbents. The IR-ATR spectra indicated the NH4- N presence on the FU- and HU loaded CaT-Zeol as well as the phosphate adsorption via ligand exchange on both geosorbents. In conclusion, both materials are better suited for P adsorption in FU than in HU, with CaT-Zeol being more effective than CaT-Pal as a dual adsorbent in FU and HU. The overall findings demonstrate the upgrade of both soil-friendly materials after adsorbing plant-available nutrients
Silver-rich sulfide mineralization in the northwestern termination of the Western Cycladic Detachment System, at Agios Ioannis Kynigos, Hymittos Mt. (Attica, Greece): A mineralogical, geochemical and stable isotope study
No full textIdentification of silver-rich sulfide mineralization in the abandoned mines at northern Hymittos Mt (central
Attica, Greece) district has made this region important due to its structural relation to the world-class Lavrion
mining district (25 km SE of Hymittos Mt.). At Agios Ioannis Kynigos mine veins of oxidized Fe-Pb-Zn-Ag ore are
hosted in mylonitic marbles that were predominantly affected by brittle-ductile deformation associated with the
West Cycladic Detachment System. The major sulfides are galena and arsenian pyrite which develop as openspace
filling (fractures and vugs), disseminations and veinlets. Galena contains abundant inclusions of Pb-As-Sb-
Cu-Ag sulfosalts (tetrahedrite group minerals, bournonite, jalpaite). An unusual silver-rich galena ore i.e from
192 to 1500 ppm Ag, is recorded from the present study, with Ag hosted mainly in Ag-tetrahedrite, acanthite and
jalpaite. Compositionally pyrite shows As enrichment and the highest As concentration i.e. up to 3.9 wt% is
found in the core of the oscillatory zoned pyrites.
Values of δ34S of galena are isotopically light (−11.2 to −12.2‰), which suggests a sedimentary component
to the ore fluid, that is likely derived from leaching of the meta-sedimentary (calc-mica schists) wall rocks.
Carbon and oxygen isotope compositions of ore-stage carbonates show values i.e δ13CV-PDB (‰)=−8.2 to
−11.7‰and δ18O=24.3 to 25.9‰and for the non-mineralized carbonates δ13CV-PDB (‰)=+0.33 to 2.52‰
and δ18O=20.8 to 26.1‰. The C and O isotopic composition of the carbonate wall rock distal to the orebody is
typical of marine carbonates, whereas hydrothermal carbonates (brown calcite and dolomite) are dominated by
an external, light C source. The lowest δ13CV-PDB values are recorded from cerussite and correspond to the low
temperature supergene alteration from meteoric waters. The homogenized values of δ18O in the mineralized
carbonates indicate interaction of fluid with host carbonates under a low fluid/rock ratio. The Pb-Zn-Ag mineralization
at Agios Ioannis Kynigos bears many similarities with the low-temperature carbonate replacementstyle
mineralization in Kamariza, Lavrion area. Ore deposition in the northern Hymittos detachment fault is
focused in the structurally upper parts of the detachment fault where circulation of meteoric fluids is dominant
in the hydrothermal system
Phosphorus-rich olivines in a composite xenolith from Morocco: implications for growth processes
No full textPhosphorus(P)-rich zones in olivine may reflect incorporation of P in excess of equilibrium
partitioning during rapid growth (e.g. Milman-Barris et al. 2008). We investigated (by optical
microscopy and electron microprobe) a composite mantle xenolith from the Middle Atlas
Mountains (Morocco) containing two lithologies, wehrlite and harzburgite, in direct contact. The
host alkali basalt (El Messbahi et al. 2015) is present on the margins of the hand sample but not
included in our thin section. Both lithologies display porphyroclastic texture and contain interstitial
devitrified glass. Large primary matrix olivine in both wehrlite and harzburgite has P2O5
concentrations ≤0.09 wt.% and nearly constant composition, Fo90, except for Fe-rich reaction rims
in contact with the interstitial devitrified glass. The P-rich interstitial spaces between these primary
matrix olivines consist of devitrified glass, secondary olivine, clinopyroxene, spinel, and apatite.
The secondary olivine ranges between Fo86-93 and is obviously enriched in P2O5, with
concentrations from 0.36-1.98 wt.%. Whereas matrix clinopyroxene in the wehrlite forms isolated
subhedral to euhedral crystals, the interstitial regions contain elongated and dendritic
clinopyroxene up to 10 μm long as well as replacive clinopyroxene rims on matrix minerals. Spinel
occurs as tiny discrete grains associated with the devitrified glass. Apatite is found only as very
small crystals embedded in devitrified glass.
High-resolution X-ray mapping of P in olivine reveals both alternating P-rich bands parallel to
crystal elongation and patchy zoning. P5+ correlates negatively with Si4+ (R = –0.90) and positively
with Na+ (R = +0.73). Correlation with total divalent cations (Mg2++Mn2++Fe2++Ca2++Ni2+) is weakly
negative (R = –0.44). Although correlation of P5+ and Al3+ is weak (R = -0.42), the combination
P5++Al3+ displays a better anticorrelation with Si4+ (R = –0.92). Overall, the observed correlations
suggest the predominant substitution mechanism is 2 IVSi4+ <=> IVP5+ + IVR3+, with some additional
accommodation by IVSi4+ +VIM2+ <=> IVP5+ + VINa+.
Because no glass was observed, the apparent olivine/melt partition coefficient could not be
directly measured. However, using the maximum P2O5 contents (1.05, 1.18 and 2.31 wt%) measured in glass in melt veins from other xenoliths from the a nearby Moroccan volcanic flow
(Baziotis et al. 2019) and the P-rich olivines from the present study, we infer a DP
ol/melt range
0.85-1.88. The most probable value is greater than unity, despite P being incompatible in olivine
during equilibrium growth. Such an apparent partitioning suggests that olivine crystallization was
rapid enough, ~1-10 K/hour, to develop a P-rich diffusive boundary layer from which the growing
olivine incorporated P in excess of equilibrium partitioning with the bulk melt pocket (Grant &
Kohn, 2013).
We consider several scenarios for the formation of the interstitial pockets, including partial melting
of the xenolith, intrusion of a metasomatic melt in an event earlier than eruption, and reaction
with the host lava during ascent
On the Color and Genesis of Prase (Green Quartz) and Amethyst from the Island of Serifos, Cyclades, Greece
No full textThe color of quartz and other minerals can be either caused by defects in the crystal structure or by finely dispersed inclusions of other minerals within the crystals. In order to investigate the mineral chemistry and genesis of the famous prase (green quartz) and amethyst association from Serifos Island, Greece, we used electron microprobe analyses and oxygen isotope measurements of quartz. We show that the color of these green quartz crystals is caused by small and acicular amphibole inclusions. Our data also shows that there are two generations of amphibole inclusions within the green quartz crystals, which indicate that the fluid, from which both amphiboles and quartz have crystallized, must have had a change in its chemical composition during the crystallization process. The electron microprobe data also suggests that traces of iron may be responsible for the amethyst coloration. Both quartz varieties are characterized by isotopic compositions that suggest mixing of magmatic and meteoric/marine fluids. The contribution of meteoric fluid is more significant in the final stages and reflects amethyst precipitation under more oxidizing conditions
Phosphorus interactions with Martian soil simulants
No full textPhosphorus (P) is an essential nutrient for plant growth. According to the vision of circular
bioeconomy, the management of nutrient-rich wastewaters should include both treatment and
utilization goals (Battista & Bolzonella, 2019). Consequently, the application of in-situ resources
utilization (ISRU), using typical Martian soil (e.g., Yen et al., 2005), is vital for the sustainability of
future long-term settlements on Mars.
Martian soil simulants, provided by The CLASS Exolith Lab from the University of Central Florida,
were tested for their phosphorus sorption capacity. Sorption of phosphate anions (PO4-P) from
aqueous solutions (AS) of KH2PO4 and sodium bicarbonate, as well as from hydrolyzed human
urine (HU) was examined at a preliminary stage, using three Martian soil simulants (MGS-1;
Rocknest soil, MGS-1S; M-WIP Reference Case B and MGS-1C; M-WIP Reference Case C; Cannon et
al. 2019). In particular, isothermal, kinetic, pH, temperature, initial sorbent concentration (5 g soil
simulant/L AS or HU, 10 g/L and 15 g/L) and desorption experiments were carried out, the duration
of which ranged from five days to three weeks.
The percentage of phosphorus removal was up to 60 % for the aqueous solutions and 24 % for the
hydrolyzed human waste. The sulfate-rich simulant (MGS-1S) exhibited the best results. The major
phases of MGS-1S are: gypsum, plagioclase, basaltic glass, pyroxene, and olivine. Temperature and
the initial pH seem to be the dominant factors affecting P sorption. Equilibrium between sorbent
and AS was achieved between five and seven days, as indicated by kinetic experiments. Isothermal
experiments at 25 0C with AS of different P concentrations displayed a linear correlation between
adsorption capacity (q) and P-concentration (r2=0.98). Maximum q was observed at 8.5 and 27
mg/g for AS and HU experiments respectively, when 5 g/L of initial sorbent concentration was
used. X-ray diffraction (XRD) of the sorbents treated with AS showed the presence of the newly
formed phases berlinite and brushite. Perhaps due to hydrolysis of the pre-existing illite,
aluminum bound with the solution’s phosphates, forming berlinite and buffering AS’s pH to lower
values. Formation of brushite is possibly indicative of gypsum (predominant phase in the raw
material) dissolution subsequently releasing sulfate anions. In a similar approach, XRD evaluation of the sorbents treated with HU revealed the newly formed phases calcite and hannayite.
Phosphate and ammonia ions were likely to bind to the sample and were precipitated within
newly formed calcium-bearing phases.
These experiments form a preliminary study of Martian soil simulants, and initial results indicate a
possible use of Martian soils as waste recipients or as fertilizers in future missions
Phosphorus and potassium recovery from anaerobically digested olive mill wastewater using modified zeolite, fly ash and zeolitic fly ash: a comparative study
No full textBACKGROUND: Nutrient recovery fromwastewater is gaining attention in the frame of circular economy. In this study, Ca(OH)2-treated zeolite (CaT-Z), lignite fly ash (FA) and zeolitic fly ash (ZFA) were primarily used to adsorb phosphate phosphorus (PO4-P) from anaerobically
digested olivemillwastewater (ADOMW). The simultaneous recovery of potassium (K)was also examined based on adsorption and desorption data. The fractionation of adsorbed P was determined as an important parameter for its plant availability.
RESULTS:MorePwasadsorbedfromADOMWonZFAandFA(upto4.35and5.21 mg g−1, respectively)thanonCaT-Z (2.62 mg g−1). An increased P adsorption on ZFA and FA was observed between incubation times of 7 and 14 days. The sequential desorption procedure verified the trend of P adsorption capacities and showed that the plant-available P (NaHCO3-P) amounted to 1.34, 2.34 and 1.69 mg g−1 CaT-Z, ZFA and FA, respectively. After 14 days, CaT-Z and ZFA adsorbed much more K (19.2 and 20.5 mg g−1, respectively) than FA (4.3mg g−1). The desorption of exchangeable K confirmed this difference. Scanning electron microscopy–energy dispersive spectrometry analyses indicated P adsorption and surface precipitation as Ca–P phases as well as K+ for Ca2+ ion exchange on the loaded adsorbents.
CONCLUSIONS: ZFA was more efficient for dual adsorption combining the properties of the zeolitic fraction (enhanced K adsorption) and pristine FA (P adsorption on Ca-bearing phases). The sufficient concentrations of plant-available P and K on the three adsorbents suggest their potential use as soil amendments
Melt inclusions in spinel from a composite mantle xenolith
No full textComposite mantle xenoliths from the Cima Volcanic Field (CA, USA) contain a variety of melt (now glassy)
inclusions hosted within mantle phases. The compositions and textures of these melt inclusions have the potential
to constrain their trapping processes, melt sources, and the rates of ascent of their parent xenoliths. Here
we focus on unusual spinel-hosted melt inclusions from one composite xenolith, reporting glass and daughter
mineral compositions and textures and attempting to reconstruct inclusion bulk compositions. The xenolith
contains spinel-hosted melt inclusions in its harzburgite, olivine-websterite and lherzolite layers; there are none
in its orthopyroxenite layer.
The glass compositions and reconstructed bulk compositions of the partly-crystallized inclusions correspond to
alkaline intermediate melts, mostly trachyandesites. Such melts are most likely to be generated and trapped by
vapor-undersaturated phlogopite or amphibole dehydration melting to an assemblage of liquid + spinel + olivine
± pyroxenes. We modeled the near-liquidus phase relations of the inclusion bulk compositions and noted the
closest approach of each inclusion to simultaneous saturation with spinel and either phlogopite or amphibole,
resulting in estimated trapping pressures of ~0.5–1.5 GPa and temperatures of ~1000–1100 ◦C. The large size of
the hosting spinel grains suggests a slow process associated with these breakdown reactions, probably thinning of
the lithosphere and steepening of the geotherm during regional extension.
A linear correlation between the vesicle area and inclusion area (as proxies for volume) suggests an in-situ
exsolution process from melts of relatively uniform volatile initial contents, consistent with trapping of vaporundersaturated
melts that later exsolve vapor during cooling and daughter crystal growth. A negative correlation
between the glass content in melt inclusions and the size of the inclusion itself suggests a control on the
degree of crystallinity with the size. There appears to be a two-stage cooling history captured by the inclusions,
forming first prismatic daughter crystals and large round vesicles at the wall of the inclusion, followed by
quenching to form a mat of fine crystallites and small vesicles in most inclusions. We connect the final quench to
rapid ascent of the xenolith in its host melt, which also triggered partial breakdown of remaining amphibole to
fine glassy symplectites
Rapid growth of phosphorus-rich olivine in mantle xenolith from Middle Atlas Mountains (Morocco, Africa)
No full textPhosphorus(P)-rich zones in olivine may reflect incorporation of P in excess of equilibrium partitioning during rapid growth (e.g. Milman-Barris et al. 2008). We investigated a mantle xenolith from Middle Atlas Mountains (Morocco) by optical microscopy and electron microprobe. It contains spinel-bearing lherzolite and orthopyroxenite layers, cross-cut by veins dominated by glass and secondary phases including P-rich olivines. The host lava, presumed to be alkali basalt (El Messbahi et al. 2015), is present on the margins of the hand sample but not included in our thin section. The studied melt veins (MV) generally contain Ol+Gl+Cpx+Pl+Spl_Ap. Olivines in the MV have (Fo72,1-83,4) with 0.02-0.3 wt.% P2O5; olivines with P2O5 >0.1 wt.% are Fo75,3-82,8. Some olivine grains are inclusion-free; others contain rounded glass inclusions or subhedral spinel or ilmenite inclusions. Olivines is generally found in contact with plagioclase and glass. Glass (5-15 vol%) has variable composition with P2O5 up to 1.52 wt.%, K2O 1.65-2.37 wt%, CaO 6.39-9.55 wt%, Na2O 0.78-6.70 wt% and SiO2 45.2-49.6 wt%. Where glass is in contact with matrix olivine, Fe-rich outer rims on olivine indicate mineral-melt reaction. In MgO variation diagrams, glass compositions display a coherent single trend for all oxides, with the exception of a discrete low-Na group. Clinopyroxene is present both as isolated subhedral to euhedral crystals within the MV and as replacive rims on matrix minerals. Very fine-grained dendritic clinopyroxene quench crystals up to 10 _m long are also present. Plagioclase occurs as prismatic, flow-oriented crystals parallel or sub-parallel to the layering. Spinel shows anhedral and euhedral shapes and occurs both as inclusions in olivine and as discrete grains associated with plagioclase and glass. Spinel in contact with glass shows a spongy outer rim and normal zonation towards Fe-rich rim compositions. Apatite is found mostly as very small crystals embedded in glass. High-resolution X-ray mapping of P in olivine reveals narrow P-rich bands parallel to crystal facets. P correlates negatively with Si4+, poorly with divalent cations (Mg+Fe+Ca), and positively with Al3+, suggesting a substitution 2IV Si4+ =IV P5++IV R3+. Furthermore, P is concentrated mainly at the rim of the olivine, in contact with surrounding glass. DP(OL/MELT) has a wide range (0.02 to 1.6), with the lowest numbers thought to represent equilibrium and higher numbers non-equilibrium partitioning via solute trapping during rapid growth (e.g. Watson et al. 2015). The imperfect correlation between P and Al in our data implies either diffusive relaxation of Al gradients or, judging by dynamic experiments (Grant & Kohn, 2013), cooling rates _1-10°C/h that generate disequilibrium P solute trapping but near-equilibrium Al incorporation. Early-crystallized olivine grew slowly enough to incorporate P by equilibrium partitioning, suggesting that no P-rich boundary layer developed despite slow diffusion of P in melts. Olivine rim crystallization, though was rapid enough to over-enrich P, by more than can be associated with concentration of P into a decreasing mass of residual melt (Shea et al. 2015). The apparent partition coefficient between olivine rims and adjacent melt suggests DP (OL/MELT) in the range 0.13-0.19
