Sequential geochemical extractions and mineralogy of Fe-bearing minerals of mantle rocks in the Samail Ophiolite, Oman

2020 ◽  
Author(s):  
Zena Severin ◽  
Jessica L. Till ◽  
Oman Drilling Project Phase 1 Science Party
Keyword(s):  
Sodium Acetate ◽  
Room Temperature ◽  
Extraction Procedure ◽  
Optical Microscope ◽  
Fe Oxide ◽  
Oxide Hydroxide ◽  
Chemical Extractions ◽  
Thrust Zone ◽  
Reducible Oxides ◽  
The Individual

<p>Within the Samail Ophiolite, Oman, there are intervals of listvenite outcrops between layers of serpentinite zones above the basal thrust zone, atop the metamorphic sole. Near the base of the ophiolite mantle section, some peridotites underwent 100% carbonation from metasomatic introduction of CO<sub>2</sub>-bearing fluids (~100°C) to form listvenites during the time of emplacement (97 ± 29 Ma, Falk and Kelemen, 2015). The carbonate rocks comprise mostly magnesite and/or dolomite, quartz, spinel, and Fe-(hydr)oxides; with carbonates as the sole Mg-minerals and quartz as the only silicate phase. The aim of this study is to chemically and petrographically investigate the Fe-bearing minerals within the fluid-altered mantle rocks in drill core samples from hole BT1B of the ICDP Oman Drilling Project. We investigated the quantities of Fe-oxide/hydroxide phases through a series of chemical extractions (Poulton and Canfield, 2005) via atomic absorption spectroscopy in addition to optical microscope/ SEM/EDS analysis. Sequential chemical extractions are useful for recognizing iron pools based on the minerology. Extractions preformed at room temperature show varying proportions of carbonate-associated Fe (sodium acetate), reducible oxides (citrate-dithionite), magnetite (oxalate), and HCl-extractable Fe(II). The amount of Fe in carbonates based on sodium acetate extraction ranges from 17-54% of the overall extracted iron (12-28 ‰) in the samples. The same extraction performed at 50°C for twice as long resulted in higher proportions of carbonate-associated Fe extracted with a range of 44-85% of the total extracted iron (15-35 ‰). Easily reducible iron quantities from a diluted HCl solution extraction display the lowest overall Fe fractions at 6.2-25% following the room temperature acetate and 2.6-6.2% after the 50°C acetate extraction. Reducible oxides extracted by dithionite were wide ranging (8.3-49%) as a proportion of the overall extracted iron, with similar results following the 50°C acetate step (5.3-48%). Oxalate extraction succeeding the room temperature acetate revealed magnetite proportions of 13-28%, while the increased temperature and time in the first step (acetate extraction) resulted in significantly lower proportions of Fe extracted by oxalate (3.1-10%). Falk and Kelemen (2015) suggest significant amounts of poorly crystalline Fe-phases or amorphous oxides within the listvenites not detected by X-ray diffraction, but we do not see evidence of this based on the relatively small HCl fractions. Further examination of the total elemental compositions of the individual solutions and electron microprobe analyses will reveal more details about the Fe-minerals dissolved in each extract and weather they represent separate Fe-oxide/hydroxide phases.    </p><p> </p><p>Falk, E. S., & Kelemen, P. B. (2015). Geochemistry and petrology of listvenite in the Samail ophiolite, Sultanate of Oman: Complete carbonation of peridotite during ophiolite emplacement.<em> Geochimica et Cosmochimica Acta</em>, 160, 70-90.</p><p>Poulton, S. W., & Canfield, D. E. (2005). Development of a sequential extraction procedure for iron: implications for iron partitioning in continentally derived particulates. <em>Chemical Geology</em>, 214(3-4), 209-221.</p><p> </p>

Sequential geochemical extractions and mineralogy of Fe-bearing minerals in carbonatized mantle rocks in the Samail Ophiolite, Oman 

2021 ◽  
Author(s):  
Zena Severin ◽  
Jessica L. Till ◽  
Oman Drilling Project Phase 1 Science Party
Keyword(s):  
Sodium Acetate ◽  
Room Temperature ◽  
Optical Microscope ◽  
Fe Oxide ◽  
Chemical Extractions ◽  
Oxide Phases ◽  
Thrust Zone ◽  
Reducible Oxides ◽  
Icp Analysis ◽  
Oxalate Extraction

<p>Within the Samail Ophiolite, Oman, there are intervals of listvenite outcrops between layers of serpentinite zones above the basal thrust zone, atop the metamorphic sole. Near the base of the ophiolite mantle section, some peridotites underwent 100% carbonation from metasomatic introduction of CO<sub>2</sub>-bearing fluids <200°C to form listvenites during the time of emplacement (97 ± 29 Ma, Falk and Kelemen, 2015). The carbonate rocks comprise mostly magnesite and/or dolomite, quartz, Cr-spinel, and Fe-(hydr)oxides; with carbonates as the sole Mg-minerals and quartz as the only silicate phase. The aim of this study is to chemically and petrographically investigate the Fe-bearing minerals within the fluid-altered mantle rocks in drill core samples from hole BT1B of the ICDP Oman Drilling Project. Sequential chemical extractions are useful for recognizing iron pools based on the minerology. We investigated the quantities of Fe-oxide/hydroxide phases through a series of chemical extractions (Poulton and Canfield, 2005) via atomic absorption spectroscopy in addition to optical microscope, SEM/EDS, EPMA/WDS and ICP analysis. Extractions performed at room temperature and one at 50°C included: carbonate-associated Fe (sodium acetate) targeting siderite, HCl-extractable Fe(II), reducible oxides (citrate-dithionite) targeting hematite and possible goethite, and magnetite (oxalate). Carbonate-based Fe in the listvenites from a sodium acetate extraction ranges from 12-28 mg/g, while the same extraction performed at 50°C for twice as long resulted in higher proportions of carbonate-associated Fe (15-35 mg/g). Easily reducible iron quantities from the diluted HCl solution extraction display the lowest overall Fe fractions (0.75-5.5 mg/g) following the room temperature acetate and 0.63-1.7 mg/g after the 50°C acetate extraction. Fe in reducible oxides extracted by dithionite ranged from 1.4-15 mg/g with similar result after both a room-temperature acetate and a 50°C acetate step. Oxalate extraction succeeding the room-temperature acetate yielded magnetite concentrations of 1.9-8.0 mg/g, while the increased temperature and time in the first step (acetate extraction) were followed by significantly lower amounts of Fe extracted by oxalate (0.47- 3.6 mg/g). Additionally, the same extractions were performed on a pure siderite sample from Greenland. For siderite samples crushed a week prior to analysis, the carbonate-associated Fe in sodium acetate extract was 165±17 mg/g; the sidenote yielded 42 wt% of overall extracted Fe (392±33 mg/g). This is only slightly lower than the expected 48.2 wt% of Fe for a pure siderite sample. Dilute HCl extractions display results of 126±5.4 mg/g, dithionite solution extracted 25±0.5 mg/g and oxalate proportions were 76±9 mg/g. Due to possible oxidation of siderite to magnetite occurring during the time between powdering the samples and analysis, the full dissolution of siderite may not be fully represented in only the acetate. Microprobe data shows a total amount of FeO in carbonates as 1.3-10.8 wt%. This is more than or similar to the acetate and HCl proportions of Fe which represent carbonate associated minerals in the listvenites. Data obtained from EMPA and ICP will additionally be discussed in relation to the Fe-oxide phases with relation to the listvenites minerology.</p>

Room-temperature phosphorescence of compounds adsorbed on sodium acetate

1977 ◽  
Vol 49 (14) ◽  
pp. 2164-2169 ◽  
Author(s):  
R. M. A. Von Wandruszka ◽  
R. J. Hurtubise
Keyword(s):  
Sodium Acetate ◽  
Room Temperature ◽  
Room Temperature Phosphorescence

scholarly journals Powder properties of binary mixtures of chloroquine phosphate with lactose and dicalcium phosphate

2010 ◽  
Vol 46 (3) ◽  
pp. 531-537
Author(s):  
Michael Ayodele Odeniyi ◽  
Collins Chidi Onyenaka ◽  
Oludele Adelanwa Itiola
Keyword(s):  
Binary Mixtures ◽  
Internal Flow ◽  
Optical Microscope ◽  
Volume Reduction ◽  
Dicalcium Phosphate ◽  
Flow Properties ◽  
Maximum Volume ◽  
Cohesive Properties ◽  
Particle Size And Shape ◽  
The Individual

A study was conducted on the packing and cohesive properties of chloroquine phosphate in binary mixtures with lactose and dicalcium phosphate powders. The maximum volume reduction due to packing as expressed by the Kawakita constant, a, and the angle of internal flow, θ, were the assessment parameters. The individual powders were characterized for their particle size and shape using an optical microscope. Binary mixtures of various proportions of chloroquine phosphate with lactose and dicalcium phosphate powders were prepared. The bulk and tapped densities, angles of repose and internal flow, as well as compressibility index of the materials were determined using appropriate parameters. The calculated and determined values of maximum volume reduction for the binary mixtures were found to differ significantly (P< 0.05), with the Kawakita plot being more reliable in determining the packing properties. Diluent type was found to influence the flow properties of the mixtures, with dicalcium phosphate giving predictable results while mixtures containing lactose were anomalous with respect to flow. The characterization of the packing and cohesive properties of the binary mixtures of chloroquine with lactose and dicalcium phosphate would be useful in the production of powders, tablets, capsules and other drug delivery systems containing these powders with desirable and predictable flow properties.

scholarly journals Evaluation of Pre-heating Effects on Marginal Adaptation of Resin-based Materials

2018 ◽  
Vol 55 (2) ◽  
pp. 238-242 ◽  
Author(s):  
Ionut Taraboanta ◽  
Simona Stoleriu ◽  
Gianina Iovan ◽  
Antonia Moldovanu ◽  
Andrei Georgescu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Composite Resin ◽  
Optical Microscope ◽  
Marginal Adaptation ◽  
Gap Formation ◽  
Solution Ph ◽  
Filling Materials ◽  
Heating Effects ◽  
Direct Restoration ◽  
Materials Used

The aim of the study was to compare the marginal adaptation of three different resin-based materials used for direct restoration: hybrid composite resin (Gaenial Posterio, GC Corporation), a compomer (Dyract eXtra, Dentsply Sirona), and a giomer (Beautifil II, Shofu Dental) applied at room temperature or after preheated at preheating 50 and 60oC. Class II cavities were prepared on proximal surfaces of extracted teeth and randomly divided in 3 groups according to the material used for restoration. In each group five cavities were restored using the materials at room temperature (subgroup 1), five cavities were restored using preheated materials at 50şC (subgroup 2), and five cavities were restored using preheated materials at 60şC (subgroup 3). The teeth were stored in distilled water for 14 days and then were immersed in 2% methylene blue buffered dye solution (pH = 7) for 4 hours. The teeth were transversally cut and the sections were examined using optical microscope (Carl-Zeiss AXIO Imager A1m) at 50x magnification and the dye penetration was evaluated according to 4 scores. Decreased microleakage and fewer gap formation were recorded for all filling materials after they have been heated at 50 or 60oC. Pre-warming of resin-based materials improves the adaptation of these materials to tooth structures.

Heterobimetallische 3d-4f-Komplexe mit Bis(1,2-dithiooxalato)nickelat(II) als planarem Brückenbaustein / Heterobimetallic 3d-4f-Complexes with Bis(1,2-dithiooxalato)nickelate(II) as Planar Bridging Block

2005 ◽  
Vol 60 (11) ◽  
pp. 1149-1157 ◽  
Author(s):  
Matthias Siebold ◽  
Alexandra Kelling ◽  
Uwe Schilde ◽  
Peter Strauch
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Lanthanide Ions ◽  
Water Molecules ◽  
Unit Cell Parameters ◽  
Ionic Radii ◽  
X Ray ◽  
Cell Parameters ◽  
Heterobimetallic Complexes ◽  
The Individual

Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)n}2- {Ni(dto)2}3]・xH2O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9 - 12). With [{Nd(H2O)5}2{Ni(S2C2O2)2}3]・xH2O (x = 10 - 12) (1) and [{Er(H2O)4}2{Ni(S2C2O2)2}3]・xH2O (x = 9 - 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P21/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2) Å , β = 98.907(9)° and Z = 2; 2, triclinic in P1̅ with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) Å , α = 107.899(4)°, β = 91.436(4)°, γ = 112.918(4)° and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions.

scholarly journals XRD Identification of Ore Minerals during Cruises: Refinement of Extraction Procedure with Sodium Acetate Buffer

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 160
Author(s):  
Jelena Milinovic ◽  
Ágata Alveirinho Dias ◽  
Ana I. Janeiro ◽  
Manuel F. C. Pereira ◽  
Sofia Martins ◽  
...  
Keyword(s):  
Sodium Acetate ◽  
Extraction Procedure ◽  
Xrd Analysis ◽  
Acetate Buffer ◽  
Sodium Acetate Buffer ◽  
Sediment Samples ◽  
New Information ◽  
Ore Minerals ◽  
Mid Atlantic Ridge ◽  
Seafloor Sediments

The on-board identification of ore minerals during a cruise is often postponed until long after the cruise is over. During the M127 cruise, 21 cores with deep-seafloor sediments were recovered in the Trans-Atlantic Geotraverse (TAG) field along the Mid Atlantic Ridge (MAR). Sediments were analyzed on-board for physicochemical properties such as lightness (L*), pH and Eh. Selected samples were studied for mineral composition by X-ray powder diffraction (XRD). Based on XRD data, sediment samples were separated into high-, low- and non-carbonated. Removal of carbonates is a common technique in mineralogical studies in which HCl is used as the extraction agent. In the present study, sequential extraction was performed with sodium acetate buffer (pH 5.0) to remove carbonates. The ratio between the highest calcite XRD reflection in the original samples (Iorig) vs its XRD-reflection in samples after their treatment with the buffer (Itreat) was used as a quantitative parameter of calcite removal, as well as to identify minor minerals in carbonated samples (when Iorig/Itreat > 24). It was found that the lightness parameter (L*) showed a positive correlation with calcite XRD reflection in selected TAG samples, and this could be applied to the preliminary on-board determination of extraction steps with acetate buffer (pH 5.0) in carbonated sediment samples. The most abundant minerals detected in carbonated samples were quartz and Al- and Fe-rich clays. Other silicates were also detected (e.g., calcic plagioclase, montmorillonite, nontronite). In non-carbonated samples, Fe oxides and hydroxides (goethite and hematite, respectively) were detected. Pyrite was the dominant hydrothermal mineral and Cu sulfides (chalcopyrite, covellite) and hydrothermal Mn oxides (birnessite and todorokite) were mineral phases identified in few samples, whereas paratacamite was detected in the top 20 cm of the core. The present study demonstrates that portable XRD analysis makes it possible to characterize mineralogy at cored sites, in particular in both low- and high-carbonated samples, before the end of most cruises, thus enabling the quick modification of exploration strategies in light of new information as it becomes available in near-real time.

Simple Manual Procedure for Determination of Serum Triglycerides

1975 ◽  
Vol 21 (6) ◽  
pp. 768-770 ◽  
Author(s):  
Jose Mendez ◽  
Barry Franklin ◽  
Harry Gahagan
Keyword(s):  
Quality Control ◽  
Calibration Curve ◽  
Room Temperature ◽  
Extraction Procedure ◽  
Serum Triglycerides ◽  
Modified Method ◽  
Color Development ◽  
Significant Difference ◽  
Control Samples

Abstract We describe a modified method for determining serum triglycerides (triacylglycerols), which is based on the heptane extraction procedure of Gottfried and Rosenberg [Clin. Chem. 19, 1077 (1973)] with the stable saponification, oxidation, and color development reagents of Neri and Frings [Clin. Chem. 19, 1201 (1973)]. This modified method eliminates one heating step, reduces saponification time to 5 min, absorbances are read at room temperature, and the calibration curve is linear to 3.0 g/liter. A sample comparison between the proposed method and the automated Block and Jarrett [Am. J. Med. Technol. 35, 1 (1969)] procedure showed no significant difference (r = 0.98). The coefficient of variation (47 duplicate samples) for the modified method was 6.3%. Further validation was obtained from analysis of quality-control samples; the proposed method gave equivalent values.

Effects of Extrusion on the Mechanical Properties and Damping Capacity of Mg-1.8Cu-0.5Mn Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 257-260 ◽  
Author(s):  
Zhen Yan Zhang ◽  
Li Ming Peng ◽  
Xiao Qin Zeng ◽  
Lin Du ◽  
Lan Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Damping Capacity ◽  
X Ray Diffraction ◽  
Dynamic Mechanical Analyzer ◽  
X Ray ◽  
Solute Atoms

Effects of extrusion on mechanical properties and damping capacity of Mg-1.8wt.%Cu -0.5wt.%Mn (MCM1805) alloy have been investigated. Tensile tests and dynamic mechanical analyzer were respectively used to measure tensile properties and damping capacity at room temperature of as-cast and as-extruded MCM1805 alloy. The microstructure was studied using optical microscope, X-ray diffraction and scanning electron microscope with an energy dispersive X-ray spectrometer. Granato-Lücke model was used to explain the influences of extrusion on damping capacity of MCM1805 alloy. The results showed that extrusion dramatically decreases the grain size but has little influence on phase composition and solute atoms concentration of MCM1805 alloy, and the grain refinement was the dominant reason for the obvious increase of tensile properties and decrease of internal friction of MCM1805 alloy.

Thermally induced transformations of Fe oxide-stabilized residues from waste incineration

2001 ◽  
Vol 65 (5) ◽  
pp. 635-643 ◽  
Author(s):  
M. A. Sørensen ◽  
C. Bender Koch
Keyword(s):  
Heavy Metals ◽  
Room Temperature ◽  
Waste Incineration ◽  
Oxide Phase ◽  
Waste Incinerator ◽  
Air Pollution Control ◽  
Fe Oxide ◽  
Thermally Induced ◽  
Co Precipitation ◽  
Reducing Gases

AbstractAir pollution control (APC) facilities at waste incinerator plants produce large quantities of solid residues rich in salts and heavy metals. Heavy metals are readily released to water from the residues and it has, therefore, been found suitable to apply a rapid co-precipitation/adsorption process as a means to immobilize the toxic elements. In the ‘Ferrox process’, this immobilization is based on co-precipitation with an Fe(III) oxide formed by oxidation of Fe(II) by air in an aqueous slurry with the APC residue at alkaline pH. In this work we have undertaken a Mössbauer spectroscopy study of the Fe oxide phase formed by precipitation at room temperature and of the oxides present after heating to 600 and 900°C. The only Fe oxide observed in the Ferrox product at room temperature is a very poorly crystalline ferrihydrite. Analytical transmission electron microscopy showed that the main elements associated with the ferrihydrite are Si and Ca. Following heating to 600°C the oxide is still characterized as an amorphous Fe oxide, and it is probable that Si associated with the ferrihydrite is decisive in preventing crystallization. After the 900°C treatment a transformation into defect maghemite is observed. Reducing gases produced from carbon in the samples probably induces this transformation. It eases, thus, the reduction of Fe(III) and the consequent formation of magnetite that eventually oxidizes to maghemite during cooling in air.

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