69 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
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
The potential of phosphorus in clinopyroxene as a geospeedometer: Examples from mantle xenoliths
No full textWe investigate the potential to use concentrations and zoning patterns of phosphorus (P) in clinopyroxene as indicators of
the rates of igneous and metasomatic processes, comparable to recent applications of P in olivine but applicable to more
evolved rocks and lower temperatures of crystallization. Few high-P pyroxenes have been previously reported, and none have
been analyzed in detail for the mechanism of P enrichment or the implications for mineral growth kinetics. Here, we report the
discovery and characteristics of exotic phosphorus-rich secondary clinopyroxene in glassy pockets and veins in composite
mantle xenoliths from the Cima Volcanic Field (California, USA) and the Middle Atlas Mountains (Morocco, West Africa).
These glass-bearing xenoliths preserve evidence of melt infiltration events and the contrasting behavior of P in their pyroxene
crystals constrains the different rates of reaction and extents of equilibration that characterized infiltration in each setting. We
report optical petrography and chemical analysis of glasses and minerals for major elements by electron microprobe microanalyzer
and trace elements by laser-ablation Inductively Coupled Plasma Mass Spectrometry. The Cima Volcanic Field specimen
shows one end-member behavior, with unzoned P-rich clinopyroxene in a melt pocket. We attribute this occurrence to a
slow crystallization process that occurred after the melt temperature reached near-equilibrium with the host rock and during
which the P concentration in the melt was buffered by apatite saturation. In the Morocco xenolith, by contrast, clinopyroxene
exhibits zonation with P increasing all the way to the rim, in contact with the glass. We ascribe this feature to a rapid growth
process in which excess P was incorporated into the growing clinopyroxene from a diffusive boundary layer. We demonstrate
quantitative agreement between the enrichment of P and other trace elements and their expected diffusion and partitioning
behavior during rapid growth. We suggest that P has not been widely reported in clinopyroxene in large part because it
has rarely been looked for and that its analysis offers considerable promise as a kinetic indicator both in xenoliths and volcanic
rocks
PHOSPHORUS ZONING FROM SECONDARY OLIVINE IN MANTLE XENOLITH FROM MIDDLE ATLAS MOUNTAINS (MOROCCO, AFRICA): IMPLICATIONS FOR CRYSTAL GROWTH KINETICS
No full textMantle xenolith samples in contact with basalt flows were collected from the
Tafraoute maar in Morocco. Discrete melt veins are present in one xenolith sample,
crosscutting primary layering and foliation. We used both optical microscopy and
electron microprobe analysis to characterize the glasses and minerals in the melt
veins. The melt veins consist of glass and crystals of olivine, clinopyroxene,
plagioclase, spinel and apatite. The olivine in the melt veins is quite distinct from the
same mineral within the matrix due to its characteristic P-enriched rims (up to 0.3
wt.%). Correlations between Al and P, as well as experimentally determined partition
coefficient for P, point towards non-equilibrium partitioning during rapid crystal
growth at the end of crystallization
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
Microtextures in the Chelyabinsk impact breccia reveal the history of Phosphorus‐Olivine‐Assemblages in chondrites
No full textAbstract The geochemistry and textures of phosphate minerals can provide insights into the geological histories of parental asteroids, but the processes governing their formation and deformation remain poorly constrained. We assessed phosphorus‐bearing minerals in the three lithologies (light, dark, and melt) of the Chelyabinsk (LL5) ordinary chondrite using scanning electron microscope, electron microprobe, cathodoluminescence, and electron backscatter diffraction techniques. The majority of studied phosphate grains appear intergrown with olivine. However, microtextures of phosphates (apatite [Ca 5 (PO 4 ) 3 (OH,Cl,F)] and merrillite [Ca 9 NaMg(PO 4 ) 7 ]) are extremely variable within and between the differently shocked lithologies investigated. We observe continuously strained as well as recrystallized strain‐free merrillite populations. Grains with strain‐free subdomains are present only in the more intensely shocked dark lithology, indicating that phosphate growth predates the development of primary shock‐metamorphic features. Complete melting of portions of the meteorite is recorded by the shock‐melt lithology, which contains a population of phosphorus‐rich olivine grains. The response of phosphorus‐bearing minerals to shock is therefore hugely variable throughout this monomict impact breccia. We propose a paragenetic history for P‐bearing phases in Chelyabinsk involving initial phosphate growth via P‐rich olivine replacement, followed by phosphate deformation during an early impact event. This event was also responsible for the local development of shock melt that lacks phosphate grains and instead contains P‐enriched olivine. We generalize our findings to propose a new classification scheme for Phosphorus‐Olivine‐Assemblages (Type I–III POAs). We highlight how POAs can be used to trace radiogenic metamorphism and shock metamorphic events that together span the entire geological history of chondritic asteroids
FIRST DISCOVERY OF ASIMOWITE IN AN ANTARCTIC METEORITE (GROSVENOR MOUNTAINS 17151, L6, ORDINARY CHONDRITE).
No full textOrdinary chondrites (OCs) preserve a record of impact events due to collision(s) among their parent asteroids that helps constrain the shock conditions and parameters (in particular, size and relative encounter velocity) of impactors and targets. In turn, the co-evolution of planetesimal sizes and their orbital excitation can distinguish among scenarios for the early evolution of the solar system. Shock parameters can be inferred from high-pressure (HP) minerals that are often found in melt veins (MV). Herein, we report the first discoveries of nine HP minerals in the recently recovered L6 chondrite, GRO 17151 (Grosvenor Mountains, season 2017-2018). Furthermore, we report the first discovery of the Fe-rich analogue of wadsleyite, asimowite, from an Antarctic meteorite (3rd known occurrence altogether).
One large main MV is visible in each of two studied sections. The vein contains HP polymorphs of olivine (ringwoodite + ahrensite + wadsleyite + asimowite), orthopyroxene (majorite), Na-pyroxene (albitic jadeite), phosphate (tuite), silica (stishovite) and oxide (xieite). Using these observations, we are able to constrain the impact record of this meteorite.
The GRO 17151 was recovered by the Antarctic Search for Meteorites (ANSMET) expedition in the 2017-2018 season and classified as type L6 [1]. Two single-polished thin sections (GRO 17151-8, GRO 17151-9) were examined for shock indicators, with a focus on the MVs and their HP phases. We used optical microscopy, a JEOL JSM-IT300LV scanning electron microscope (SEM), a dispersive confocal Renishaw inVia Reflex Raman microscope (514 nm laser), a Zeiss 1550VP field-emission SEM with energy-dispersive X-ray spectrometry (EDS) and electron backscatter diffraction (EBSD) capability, and a JEOL JXA 8530F electron probe micro-analyzer. Around 20 areas of the MV were analyzed for texture, mineral chemistry, and Raman spectroscopy (RS), and a few of them with EBSD.
Petrography, mineral chemistry, and structure: In the groundmass of GRO 17151, olivine grains show strong mosaicism and planar deformation features. The single thick MV is presumed to be the result of a strong shock event; it is in contact with olivine but occasionally also with pyroxene and metal grains. The width of the thickest MV is nearly constant (~500 to 600 μm). The MV consists of glass, silicate clasts (olivine, pyroxene, and plagioclase), sulfides, chromite, and Fe-Ni metal.
HP minerals. We have observed 9 HP phases including ringwoodite (rw), ahrensite (ahr), wadsleyite (wd), asimowite (asi), majorite (maj), albitic jadeite (jd), stishovite (stv), tuite (tu), and xieite (xie). The MV matrix is mostly a crystallized assemblage of maj+rw+wd+magnesiowüstite (Fig. 1).
The large green crystals, up to about 250 μm, have olivine stoichiometry and variable composition from Fa15 to Fa52. Co-located RS have strong wad peaks and minor rw peaks. Turning to EBSD analysis coupled with high-spatial resolution co-located EPMA, the small BSE-bright crystals in Figs 1B and 1D are Fe-dominant (Fa>50%), yield structure solutions most consistent with wadsleyite structure (though ahr structure is difficult to distinguish by EBSD), and strong wd Raman peaks. Hence these are asimowite (Fig. 2).
Crystals of albitic jadeite [2,3] are equigranular to irregularly shaped, up to ~20 μm, and by EPMA yield the formula (Na0.43-61Ca0.07-0.08K0.02-0.085□0.27-0.45)(Al0.83-0.86Si0.16-0.19Fe0.01-0.04)Si2O6, with Ca# [100×Ca/(Ca+ Na)] in the range of 10.4-15.1. The RS of GRO 17151 albitic jadeite has a distinct major peak at 701 cm–1 and minor peaks at 204, 377, 436, 525, 574, 989, and 1038 cm–1 (Fig. 3A). The RS of near-endmember jd has major peaks at 700, 991, and 1040 cm–1 and minor peaks at 204, 375, 385, 433, 525, 575 cm–1 (RRUFF R050220.2), which is a good match even though our EPMA analysis shows that the GRO 17151 material is not near-endmember jd. As expected but not often found, the jd coexists at fine scale with stishovite, based on mixed RS (spectrum A31 in figure 3A) showing the major stv peak at ~751 cm1 and one minor peak at 231 cm1. Further, the composition of phosphate has a merrillite-like chemistry with Na2O in the range 2.58-2.74, MgO 3.38-3.51 and FeO 0.72-1.35 wt.%.
P-T-t constraints. The RS of GRO 17151 phosphate shows a mix of merrillite and tu due to partial preservation of tu from high pressure; tu suggests P ≤ 22 GPa. The P for growth of albitic jadeite and asimowite [5], which lack any stability fields, cannot be assessed. The occurrence of wd, however, suggests P > 13 GPa to at most 22 GPa (depending on T and Fe content), coexisting wd and ahr bounds the P along the upper limit of the wd field. The existence of maj suggests P of 17–20 GPa and 1800–2100 °C [4].
Pending further work, it is clear that GRO 17151 is heavily shocked, hosting at least nine HP phases indicating peak shock conditions > 17 GPa and 1800 °C. It hosts a unique record of the passage of material through space-and-time-variable high-P,T conditions. This occurrence of asimowite is the first in an Antarctic meteorite and indicates a very different paragenesis from previous reports [5]. Moreover, all the fine-grained wadsleyite()-structured material is more Fe-rich than any experimentally synthesized stable wd, even though it is not all asimowite by the 50% rule. We suggest that Fe-rich (~Fo50) olivine suffered a shock strong enough to form ringwoodite(), which thereafter, during decompression avoided back-transformation to olivine() at the equilibrium - phase loop, reaching instead the metastable branch of β-γ loop and forming a series from ~Fa40 wd to ~Fa55 asi, with traces of even more Fe-rich ahr still remaining on quench
Origin of metabasites from upper tectonic unit of the Lavrion area (SE Attica, Greece): Geochemical implications for dual origin with distinct provenance of blueschist and greenschist's protoliths
No full textSTUDY OF THE METAMORPHIC EVOLUTION OF A CARBONATE-BEARING METAPERIDOTITE FROM THE SIDIRONERO COMPLEX (CENTRAL RHODOPE, GREECE) USING P-T AND P(T)-XCO2 PSEUDOSECTIONS
No full textThe carbonate-bearing metaperidotite from Sidironero Complex, north of the Xanthi town is composed primarily of olivine and orthopyroxene megacrysts and of Ti-clinohumite, tremolite, chlorite, dolomite, magnesite, talc, antigorite and spinel group minerals. The metaperidotite underwent a prograde HP metamorphism probably isofacial with the neighboring amphibolitized eclogites. Calculated P-T and P(T)-XCO2 phase diagram sections (pseudosections) for the bulk rock composition showed that XCO2 in the fluid phase was extremely low (≤0.008) at the first stages of the metamorphism and increased up to 0.022 at the peak P-T conditions ~1.5 GPa and 690 0C. The prograde metamorphism probably started from a hydrated and carbonated assemblage including talc+chlorite+magnesite+dolomite and proceeded with tremolite and antigorite formation before olivine growth, and orthopyroxene formation after olivine growth (Ol-1). Matrix dolomite, breakdown of chlorite (Chl-1) to Cr spinel+olivine and of Ti-clinohumite to olivine+Mg-ilmenite occurred during decompression. The P-T path is constrained by the absence of clinopyroxene in the metaperidotite
GEOCHEMISTRY AND TECTONIC SETTING OF ECLOGITE PROTOLITHS FROM KECHROS COMPLEX IN EAST RHODOPE (N.E. GREECE)
No full textEclogites and partially amphibolitized eclogites from the metamorphic Kechros complex in East Rhodope are studied in order to provide the geodynamic framework for the origin of their protoliths. Geochemical evidence from whole rock major and trace element concentrations shows two distinct protolith groups. The low-Fe-Ti eclogites (Charakoma locality) have low-TiO2 content (<0.67 wt%), negative Nb anomalies, positive Sr anomalies, small negative Zr and Hf anomalies and variable enrichments in LILE (e.g. Rb and Ba). The REE patterns are characterized by strong LREE enrichment (LaN/YbN=5.45-5.81), HREE depletion (GdN/YbN=1.60-1.63) and HREE abundance within the rangeof 9-10 × chondrite. The high-Fe-Ti eclogites (Kovalo and Virsini locality) have variable Sr contents, small to moderate LILE enrichment, HREE`s similar to MORB values and absence of Nb anomalies. The REE patterns of the Kovalo and Virsini eclogites are characterized by LREE depletion and relative flat MREE HREE patterns at approximately 20-30 × chondrite concentrations. Our results suggest that the protoliths of the Low-Ti eclogites show a continental rifting tectonic environment. In contrast, the protoliths of the High-Ti eclogites indicate formation of their protoliths by partial melting in an extensional oceanic environment
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