Natural Fe-bearing aluminous bridgmanite in the Katol L6 chondrite

Bridgmanite, the most abundant mineral of the Earth’s lower mantle, has been reported in only a few shocked chondritic meteorites; however, the compositions of these instances differ from that expected in the terrestrial bridgmanite. Here, we report the first natural occurrence of Fe-bearing aluminous bridgmanite in shock-induced melt veins within the Katol L6 chondrite with a composition that closely matches those synthesized in high-pressure and temperature experiments over the last three decades. The Katol bridgmanite coexists with majorite and metal-sulfide intergrowths. We found that the natural Fe-bearing aluminous bridgmanite in the Katol L6 chondrite has a significantly higher Fe3+/ΣFe ratio (0.69 ± 0.08) than coexisting majorite (0.37 ± 0.10), which agrees with experimental studies. The Katol bridgmanite is arguably the closest natural analog for the bridgmanite composition expected to be present in the Earth’s lower mantle. Textural observations and comparison with laboratory experiments suggest that the Katol bridgmanite formed at pressures of ∼23 to 25 gigapascals directly from the chondritic melt generated by the shock event. Thus, the Katol L6 sample may also serve as a unique analog for crystallization of bridgmanite during the final stages of magma ocean crystallization during Earth’s formation.

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Elasticity of single-crystal periclase at high pressure and temperature: The effect of iron on the elasticity and seismic parameters of ferropericlase in the lower mantle

American Mineralogist ◽

10.2138/am-2019-6656 ◽

2019 ◽

Vol 104 (2) ◽

pp. 262-275 ◽

Cited By ~ 3

Author(s):

Dawei Fan ◽

Suyu Fu ◽

Jing Yang ◽

Sergey N. Tkachev ◽

Vitali B. Prakapenka ◽

...

Keyword(s):

High Pressure ◽

Single Crystal ◽

Lower Mantle ◽

High Pressure And Temperature ◽

Seismic Parameters

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Effect of water on metal-silicate partitioning of siderophile elements: a high pressure and temperature terrestrial magma ocean and core formation

Earth and Planetary Science Letters ◽

10.1016/s0012-821x(99)00156-9 ◽

1999 ◽

Vol 171 (3) ◽

pp. 383-399 ◽

Cited By ~ 110

Author(s):

Kevin Righter ◽

Michael J. Drake

Keyword(s):

High Pressure ◽

Magma Ocean ◽

Core Formation ◽

High Pressure And Temperature ◽

Effect Of Water ◽

Metal Silicate ◽

Siderophile Elements

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Natural occurrence and significance of fluids indicating high pressure and temperature

Physics and Chemistry of the Earth ◽

10.1016/0079-1946(81)90004-5 ◽

1981 ◽

Vol 13-14 ◽

pp. 9-39 ◽

Cited By ~ 12

Author(s):

Edwin Roedder

Keyword(s):

High Pressure ◽

Natural Occurrence ◽

High Pressure And Temperature

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Stabilization of S3O4 at High Pressure-Implications for the Sulfur Excess Paradox

10.21203/rs.3.rs-125867/v1 ◽

2020 ◽

Author(s):

Siyu Liu ◽

Jian Lv ◽

Pengyue Gao ◽

Andreas Hermann ◽

Guochun Yang ◽

...

Keyword(s):

High Pressure ◽

Lower Mantle ◽

Volcanic Eruptions ◽

Sulfur Oxidation ◽

Intermediate Compound ◽

Sulfur Cycle ◽

Alternative Source ◽

High Pressure And Temperature ◽

Excess Sulfur ◽

Viable Mechanism

Abstract The geological conundrum of “sulfur excess” refers to the finding that predicted amounts of sulfur, in the form of SO2, discharged in volcanic eruptions much exceeds the sulfur available for degassing from the erupted magma. Exploring the source of the excess sulfur has been the subject of considerable interest. Here, from a systematic computational investigation of sulfur oxygen compounds under pressure, a hitherto unknown S3O4 compound containing a mixture of sulfur oxidation states +II and +IV emerges and is predicted to be stabilized above a pressure of 79 GPa. We predict that S3O4 can be produced via multiple redox reactions involving subducted S bearing minerals (e.g., sulfates and sulfides) at high pressure and temperature conditions relevant to the deep lower mantle, and conversely be decomposed into SO2 and S at shallow depths of Earth. Therefore, S3O4 can be considered as a key intermediate compound to promote the decomposition of sulfates to release SO2, which offers an alternative source of the excess sulfur released during explosive eruptions. These findings provide a possible resolution to the geological paradox of “excess sulfur degassing” and a viable mechanism for understanding of S exchange between Earth’s surface and the lower mantle for the deep sulfur cycle.

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Equations of state, phase relations, and oxygen fugacity of the Ru-RuO2 buffer at high pressures and temperatures

American Mineralogist ◽

10.2138/am-2020-7060 ◽

2020 ◽

Vol 105 (3) ◽

pp. 333-343

Author(s):

Katherine Armstrong ◽

Nicki C. Siersch ◽

Tiziana Boffa-Ballaran ◽

Daniel J. Frost ◽

Tony Yu ◽

...

Keyword(s):

High Pressure ◽

Free Energy ◽

Gibbs Free Energy ◽

Oxygen Fugacity ◽

Equations Of State ◽

Experimental Studies ◽

Phase Relations ◽

Cubic Phase ◽

High Pressure And Temperature ◽

Energy Expression

Abstract Experimental studies and measurements of inclusions in diamonds show that ferric iron components are increasingly stabilized with depth in the mantle. To determine the thermodynamic stability of such components, their concentration needs to be measured at known oxygen fugacities. The metal-oxide pair Ru and RuO2 are ideal as an internal oxygen fugacity buffer in high-pressure experiments. Both phases remain solid to high temperatures and react minimally with silicates, only exchanging oxygen. To calculate oxygen fugacities at high pressure and temperature, however, requires information on the phase relations and equation of state properties of the solid phases. We have made in situ synchrotron X-ray diffraction measurements in a multi-anvil press on mixtures of Ru and RuO2 to 19.4 GPa and 1473 K with which we have determined phase relations of the RuO2 phases and derived thermal equations of state (EoS) parameters for both Ru and RuO2. Rutile-structured RuO2 was found to undergo two phase transformations, first at ~7 GPa to an orthorhombic structure and then above 12 GPa to a cubic structure. The phase boundary of the cubic phase was constrained for the first time at high pressure and temperature. We have derived a continuous Gibbs free energy expression for the tetragonal and orthorhombic phases of RuO2 by fitting the second-order phase transition boundary and P-V-T data for both phases, using a model based on Landau theory. The transition between the orthorhombic and cubic phases was then used along with EoS terms derived for both phases to determine a Gibbs free energy expression for the cubic phase. We have used these data to calculate the oxygen fugacity of the Ru + O2 = RuO2 equilibrium, which we have parameterized as a single polynomial across the stability fields of all three phases of RuO2. The expression is log10fO2(Ru – RuO2) = (7.782 – 0.00996P + 0.001932P2 – 3.76 × 10–5P3) + (–13 763 + 592P – 3.955P2)/T + (–1.05 × 106 – 4622P)/T2, which should be valid from room pressure up to 25 GPa and 773–2500 K, with an estimated uncertainty of 0.2 log units. Our calculated fO2 is shown to be up to 1 log unit lower than estimates that use previous expressions or ignore EoS terms.

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Applications of Bentonite to Soil Decontamination

Revista de Chimie ◽

10.37358/rc.18.7.6397 ◽

2018 ◽

Vol 69 (7) ◽

pp. 1695-1698

Author(s):

Marin Rusanescu ◽

Carmen Otilia Rusanescu ◽

Gheorghe Voicu ◽

Mihaela Begea

Keyword(s):

Heavy Metals ◽

Heavy Metal ◽

Laboratory Experiments ◽

Experimental Studies ◽

Heavy Metal Concentration ◽

Polluted Soil ◽

Raw Material ◽

Soil Decontamination ◽

Metal Retention ◽

Removal Of Heavy Metals

A calcium bentonite from Orasu Nou deposit (Satu Mare Romania) was used as raw material. We have conducted laboratory experiments to determine the influence of bentonite on the degree of heavy metal retention. It has been observed that the rate of retention increases as the heavy metal concentration decreases. Experimental studies have been carried out on metal retention ( Zn) in bentonite. In this paper, we realized laboratory experiments for determining the influence of metal (Zn) on the growth and development of two types of plants (Pelargonium domesticum and Kalanchoe) and the effect of bentonite on the absorption of pollutants. These flowers were planted in unpolluted soil, in heavy metal polluted soil and in heavy metal polluted soil to which bentonite was added to observe the positive effect of bentonite. It has been noticed that the flowers planted in unpolluted soil and polluted with heavy metals to which bentonite has been added, the flowers have flourished, the leaves are still green and the plants whose soils have been polluted with heavy metals began to dry after 6 days, three weeks have yellowish leaves and flowers have dried. Experiments have demonstrated the essential role of bentonite for the removal of heavy metals polluted soil.

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