Carbonatitic melts in cuboid diamonds from Udachnaya kimberlite pipe (Yakutia): evidence from vibrational spectroscopy

AbstractMicro-inclusions (1 –10 μm) in 55 diamonds of cubic habit from the Udachnaya kimberlite pipe have been studied using vibrational spectroscopy. This has revealed a multiphase assemblage in cuboid diamonds from the Udachnaya kimberlite pipe. This assemblage includes carbonates, olivine, apatite, graphite, water and silicate glasses. The micro-inclusions preserve the high internal pressure and give confidence that the original materials were trapped during growth of the host diamond. The internal pressures, extrapolated to mantle temperatures, lie within the stability field of diamond and the relatively low temperatures are typical for the formation of cuboid diamonds. In contrast to previously reported data for African diamonds, the micro-inclusions in the cuboids from Udachnaya are extremely carbonatitic in composition (H2O/(H2O+CO2) ≈5 –20%) with the observed assemblage of microinclusions similar to some types of carbonatites. The low water and silica content testify that the material in the micro-inclusions of the Udachnaya diamonds was near-solidus carbonatitic melt. Vibrational spectroscopy has provided the evidence of carbonatitic melts in cuboid diamonds.

Download Full-text

A COMPARISON BETWEEN THE STABILITY FIELD OF A CL-RICH SCAPOLITE AND THE END-MEMBER MARIALITE

10.1130/abs/2016am-279255 ◽

2016 ◽

Author(s):

Kaleo Almeida ◽

◽

David M. Jenkins

Keyword(s):

Stability Field ◽

The Stability

Download Full-text

Eclogite from central Yukon: a record of subduction at the western margin of ancient North America

Canadian Journal of Earth Sciences ◽

10.1139/e83-126 ◽

1983 ◽

Vol 20 (9) ◽

pp. 1389-1408 ◽

Cited By ~ 25

Author(s):

Philippe Erdmer ◽

Herwart Helmstaedt

Keyword(s):

North America ◽

North American ◽

Stability Field ◽

Western Margin ◽

Thrust Sheets ◽

The Stability ◽

Basic Igneous Rock ◽

Inclusion Trails ◽

Tectonic Boundary ◽

Host Rocks

Eclogite occurring in central Yukon, at Faro and near Last Peak, as lenses interleaved with muscovite–quartz blastomylonite has the chemical and field characteristics of group C rocks. From sigmoidal inclusion trails in garnet, from geothermometry and geobarometry, and from mineral parageneses, the eclogite is inferred to have a crustal protolith and to have followed a hysteretic, subduction-cycle P–T trajectory. Transformation of basic igneous rock into schist was followed by eclogite metamorphism during which pressure was at least 1000 MPa and temperature was between 600 and 700 °C. Uplifting involved passage through the stability field of glaucophane; the eclogite and its host rocks were then subjected to greenschist fades metamorphism and deformation, with temperature at approximately 400 °C. The rocks were emplaced as thrust sheets against or onto the western North American cratonal margin. The tectonic boundary ranges from nearly vertical, where it is outlined by a zone of steeply dipping mélange, to nearly horizontal beneath klippen of cataclastic rocks that lie on North American miogeoclinal strata. Together with occurrences of eclogite on strike, in Yukon, near Fairbanks (Alaska), and near Pinchi Lake (British Columbia), eclogite at Faro and near Last Peak implies that the Yukon Cataclastic Complex is a deeply eroded collision mélange that borders over 1000 km of the ancient continental margin.

Download Full-text

A model of Fe3+-kaolinite, Al3+-goethite, Al3+-hematite equilibria in laterites

Clay Minerals ◽

10.1180/claymin.1989.024.1.01 ◽

1989 ◽

Vol 24 (1) ◽

pp. 1-21 ◽

Cited By ~ 37

Author(s):

F. Trolard ◽

Y. Tardy

Keyword(s):

Stability Field ◽

Equilibrium Conditions ◽

Dissolved Silica ◽

Silica Activity ◽

Proposed Model ◽

Coexisting Phases ◽

Activity Temperature ◽

The Stability ◽

Fe Substitution ◽

Mineral Constituents

AbstractThe distribution of Fe3+-kaolinite, Al-goethite and Al-hematite and their contents of Fe and Al in bauxites and ferricretes are controlled by water activity, dissolved silica activity, temperature and particle size. The proposed model, based on ideal solid-solution equilibria in the Fe2O3-Al2O3-SiO2-H2O system, takes into account water and silica activities. By using the same considerations as those previously developed for the Fe2O3-Al2O3-H2O system, the model calculates the amounts of coexisting phases, Al or Fe substitution ratios in goethite, hematite or kaolinite, and the stability field distributions of the minerals under various conditions. Thermodynamic equilibrium conditions and element distributions within the mineral constituents are shown to be dependent on the parameters cited above. The model yields results compatible with natural observations on lateritic profiles.

Download Full-text

The chemical stability of mendipite, diaboleïte, chloroxiphite, and cumengéite, and their relationships to other secondary lead(II) minerals

Mineralogical Magazine ◽

10.1180/minmag.1980.043.331.13 ◽

1980 ◽

Vol 43 (331) ◽

pp. 901-904 ◽

Cited By ~ 15

Author(s):

D. Alun Humphreys ◽

John H. Thomas ◽

Peter A. Williams ◽

Robert F. Symes

Keyword(s):

Chloride Ion ◽

Stability Diagram ◽

Chloride Ions ◽

Ion Concentration ◽

Stability Field ◽

Cupric Ion ◽

Free Energy Of Formation ◽

High Concentrations ◽

The Stability ◽

Ph Range

SummaryThe chemical stabilities of mendipite, Pb3O2Cl2, diaboleïte, Pb2CuCl2(OH)4, chloroxiphite, Pb3CuCl2O2(OH)2, and cumengéite, Pb19Cu24Cl42 (OH)44, have been determined in aqueous solution at 298.2 K. Values of standard Gibbs free energy of formation, ΔGf°, for the four minerals are −740, −1160, −1129, and −15163±20 kJ mol−1 respectively. These values have been used to construct the stability diagram shown in fig. I which illustrates their relationships to each other and to the minerals cotunnite, PbCl2, paralaurionite, PbOHCl, and litharge, PbO. This diagram shows that mendipite occupies a large stability field and should readily form from cold, aqueous, mineralizing solutions containing variable amounts of lead and chloride ions, and over a broad pH range. The formation of paralaurionite and of cotunnite requires a considerable increase in chloride ion concentration, although paralaurionite can crystallize under much less extreme conditions than cotunnite. The encroachment of the copper minerals on to the stability fields of those mineral phases containing lead(II) only is significant even at very low relative activities of cupric ion. Chloroxiphite has a large stability field, and at given concentrations of cupric ion, diaboleïte is stable at relatively high aCl−. Cumengéite will only form at high concentrations of chloride ion.

Download Full-text

Phase equilibrium and calorimetric study of the transition of MnTiO3 from the ilmenite to the lithium niobate structure and implications for the stability field of perovskite

Physics and Chemistry of Minerals ◽

10.1007/bf00209693 ◽

1989 ◽

Vol 16 (8) ◽

pp. 727-733 ◽

Cited By ~ 11

Author(s):

Jaidong Ko ◽

Nancy E. Brown ◽

Alexandra Navrotsky ◽

Charles T. Prewitt ◽

Tibor Gasparik

Keyword(s):

Phase Equilibrium ◽

Lithium Niobate ◽

Stability Field ◽

Calorimetric Study ◽

The Stability

Download Full-text

The Stability of Icosahedral Cd-Yb

MRS Proceedings ◽

10.1557/proc-805-ll1.8 ◽

2003 ◽

Vol 805 ◽

Author(s):

Günter Krauss ◽

Sofia Deloudi ◽

Andrea Steiner ◽

Walter Steurer ◽

Amy R. Ross ◽

...

Keyword(s):

Low Temperature ◽

Ambient Temperature ◽

Mechanical Stress ◽

Single Crystals ◽

High Temperatures ◽

Low Temperatures ◽

Ambient Pressure ◽

X Ray Diffraction ◽

X Ray ◽

The Stability

ABSTRACTThe stability of single-crystalline icosahedral Cd-Yb was investigated using X-ray diffraction methods in the temperature range 20 K ≤ T ≤ 900 K at ambient pressure and from ambient temperature to 873 K at about 9 GPa. Single-crystals remain stable at low temperatures and in the investigated HP-HT-regime. At high temperatures and ambient pressure, the quasicrystal decomposes. The application of mechanical stress at low temperatures yields to the same decomposition, the formation of Cd. A reaction of icosahedral Cd-Yb with traces of oxygen or water causing the decomposition seems reasonable, but a low-temperature instability of this binary quasi-crystal cannot be ruled out totally.

Download Full-text

Decreased storage stability of creatine kinase in a cardiac reperfusion solution

Clinical Chemistry ◽

10.1093/clinchem/36.5.778 ◽

1990 ◽

Vol 36 (5) ◽

pp. 778-780 ◽

Cited By ~ 5

Author(s):

G Dunphy ◽

D Ely

Keyword(s):

Creatine Kinase ◽

Low Temperatures ◽

Storage Stability ◽

Frozen Storage ◽

Cellular Damage ◽

Prolonged Storage ◽

Cold Preservation ◽

Rat Hearts ◽

The Stability ◽

Storage Temperatures

Abstract Creatine kinase (CK; EC 2.7.3.2) has been used as an indicator of myocardial cellular damage. In this study we used a Krebs-Henseleit (KH) solution to reperfuse isolated rat hearts after 24 h of cold preservation and collected the KH reperfusate for assay of CK to assess cellular damage. We wanted to determine the stability of CK in the KH solution at different cold-storage temperatures and albumin concentrations. CK activity (mean +/- SEM) after one week of refrigeration (5 degrees C) was 93% +/- 1% of control values, whereas CK activity in nitrogen-frozen (-200 degrees C) samples was only 1.6% +/- 1% of control values, and that in samples frozen at moderately low temperatures (-10 degrees C) was 63% +/- 1% of control values. To enhance stability, we added albumin at several concentrations (49, 25, 12, and 6 g/L) to reperfusion collections in which CK had been previously determined. Specimens were frozen (-10 degrees C), then re-analyzed for CK weekly for three weeks. CK activity was maintained (100% +/- 5%) only in samples containing 25 g/L or more albumin. These data suggest that refrigeration (5 degrees C) for one week maintains normal CK activity in KH solution; however, if prolonged storage is necessary, a stabilizer such as albumin (greater than or equal to 25 g/L) will maintain analyte stability in frozen storage (-10 degrees C) for at least three weeks.

Download Full-text

The effect of solid solution on the stability of talc and 10-Å phase

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-019-1616-0 ◽

2019 ◽

Vol 174 (10) ◽

Cited By ~ 1

Author(s):

Harriet Howe ◽

Alison R. Pawley

Keyword(s):

Subduction Zones ◽

Rheological Behaviour ◽

Starting Material ◽

Stability Field ◽

Compositional Variation ◽

Thermal Breakdown ◽

Large Decrease ◽

Dehydration Reactions ◽

The Stability ◽

Fe Substitution

Abstract Talc and 10-Å phase are hydrous phases that are implicated in fluid processes and rheological behaviour in subduction zones. Natural samples of talc show limited compositional variation away from the MgO–SiO2–H2O (MSH) endmember, with only substitution of Fe2+ for Mg occurring in significant amounts. In experiments at 2 GPa, talc containing 0.48 apfu Fe2+ begins to break down in the divariant field talc + anthophyllite + quartz at ~ 550 °C, a temperature ~ 270 °C lower than in the MSH system. At 4 GPa, Fe-bearing talc breaks down over a wide temperature interval in the divariant field talc + enstatite + coesite. The large decrease in temperature of the beginning of talc breakdown shows that Fe2+ is partitioned strongly into enstatite and anthophyllite with respect to talc. In phase reversal experiments at 6.5 GPa, the beginning of the dehydration of 10-Å phase containing 0.48 apfu Fe2+ was bracketed between 575 °C and 600 °C, a temperature ~ 100 °C lower than the MSH endmember reaction. The relative positions of the talc and 10-Å phase dehydration reactions indicate that the latter is able to accommodate greater Fe substitution, and is, therefore, more stable in Fe-bearing systems. In experiments at 6.2 GPa, 650 °C in the systems MgO–Al2O3–SiO2–H2O (MASH) and Na2O–MgO–Al2O3–SiO2–H2O (NMASH), 10-Å phase was synthesised that contains up to 0.5 apfu Al in the system MASH (compared to 0.8 in the starting material) and up to 0.4 apfu Al + 0.4 apfu Na in the system NMASH (compared to 0.7 of each of Al and Na in the starting material). Further experiments are required to determine if higher Al and Na contents in 10-Å phase are possible. The much higher Al and Na contents than found in talc indicate that, as with Fe, substitution of these elements enlarges the 10-Å phase stability field with respect to talc. In contrast to the effect of Fe, Al and Na also increase the stability of 10-Å phase relative to its thermal breakdown products enstatite + coesite.

Download Full-text