Oxygen thermobarometry measurements on spinel peridotite rocks indicate that the oxygen fugacity at top of upper mantle falls within ±2 log units fayalite-magnetite-quartz (FMQ) buffer. Measurements garnet peridotites from cratonic lithosphere reveal a general decrease in fo 2 with depth, which appears to result principally effect pressure controlling Fe 3+ /Fe 2+ equilibria. Modeling experimental data indicates approximately 8 GPa, will be 5 below FMQ and level where Ni-Fe metal becomes...

Research Article| January 01, 2013 Diamonds and the Geology of Mantle Carbon Steven B. Shirey; Shirey Department Terrestrial Magnetism, Carnegie Institution Washington, 5241 Broad Branch Road, NW, DC 20015, U.S.A., shirey@dtm.ciw.edu Search for other works by this author on: GSW Google Scholar Pierre Cartigny; Cartigny Laboratoire de Géochimie des Isotopes Stables l’Institut Physique du Globe Paris, UMR 7154, Université Paris Denis-Diderot, PRES Sorbonne Paris-Cité, Office n°511, 1 rue...

In order to test planetary accretion and differentiation scenarios, we integrated a multistage core-mantle model with N-body simulations. Impacts between embryos planetesimals result in magma ocean formation episodes of core formation. The combines rigorous chemical mass balance metal-silicate element partitioning data. primary constraint on the combined is composition Earth's primitive mantle, Martian fractions metallic cores Earth Mars. refined by least squares minimization up five fitting...

The distributions of major and minor elements in Earth's core mantle were primarily established by high pressure, temperature metal–silicate partitioning during segregation. behaviors moderately siderophile can be used to constrain the pressure–temperature conditions formation core's composition. We performed experiments study Ni, Co, V, Cr, Si, O between silicate melt Fe-rich metallic a multianvil press diamond anvil cell, up 100 GPa 5700 K. Combining our new results with data from 18...

The composition of Earth's atmosphere depends on the redox state mantle, which became more oxidizing at some stage after core started to form. Through high-pressure experiments, we found that Fe2+ in a deep magma ocean would disproportionate Fe3+ plus metallic iron high pressures. separation this raised oxidation upper changing chemistry degassing volatiles formed oxidized species. Additionally, resulting gradient allowed dissolved CO2 from precipitate as diamond depth. This explains...

Phase transitions and the chemical composition of minerals in Earth's interior influence geophysical interpretations its deep structure dynamics. A pressure-induced spin transition olivine has been suggested to iron partitioning depletion, resulting a distinct layered lower mantle. For more realistic mantle (pyrolite), we observed considerable change iron-magnesium partition coefficient at about 40 gigapascals that is explained by much pressures. However, only small depletion major...

Although water controls the biology and geology of surface, hydrogen is perhaps most poorly constrained compositional variable in bulk Earth. Its concentration upper mantle appears to be controlled by its solubility as hydroxyl nominally anhydrous silicate phases, olivine, pyroxene, garnet, wadsleyite, ringwoodite. Here we describe a series experiments showing that H 2 O olivine at 12 GPa increases with temperature 8900 ppm weight 1250°C decreases higher onset melting. Sample...

Research Article| June 01, 2008 The Upper Mantle and Transition Zone Daniel J. Frost *Bayerisches Geoinstitut, University of Bayreuth Bayreuth, Germany D95447 E-mail: Dan.Frost@uni-bayreuth.de Search for other works by this author on: GSW Google Scholar Elements (2008) 4 (3): 171–176. https://doi.org/10.2113/GSELEMENTS.4.3.171 Article history first online: 09 Mar 2017 Cite View This Citation Add to Manager Share Icon Facebook Twitter LinkedIn MailTo Tools Get Permissions Site Frost; Zone....

The solubility of carbon in olivine, enstatite, diopside, pyrope, MgAl2O4 spinel, wadsleyite, ringwoodite, MgSiO3–ilmenite and MgSiO3–perovskite has been quantified. Carbon-saturated crystals were grown from carbonatite melts at 900–1400 °C 1.5 to ∼ 26 GPa piston cylinder or multi-anvil presses using enriched > 99% the 13C isotope. In upper mantle silicates, increases as a function pressure maximum 12 ppm by weight olivine 11 GPa. No clear dependence on temperature, oxygen fugacity iron...

Seismic shear anisotropy in the lowermost mantle most likely results from elastic and lattice preferred orientation of its constituent minerals, including perovskite, post-perovskite, ferropericlase. Measurements single-crystal (Mg0.9Fe0.1)O up to 69 gigapascals (GPa) show that it increased considerably across pressure-induced spin transition iron between 40 60 GPa. Increasing content further enhances anisotropy. This leads at least 50% stronger (Mg,Fe)O compared MgO, which is typically used...

We present new equation‐of‐state (EoS) data acquired by shock loading to pressures up 245 GPa on both low‐density samples (MgSiO 3 glass) and high‐density, polycrystalline aggregates perovskite + majorite). The latter were synthesized using a large‐volume press. Modeling indicates that these materials transform perovskite, postperovskite, and/or melt with increasing pressure their Hugoniots. fit our results together existing P ‐ V T from dynamic static compression experiments constrain the...

The amount of heat flowing from Earth's core critically determines the thermo-chemical evolution both and lower mantle. Consisting primarily a polycrystalline aggregate silicate perovskite ferropericlase, thermal boundary layer at very base mantle regulates flow core, so that conductivity (k) these mineral phases controls entering lowermost Here we report measurements lattice pure, Al-, Fe-bearing MgSiO(3) 26 GPa up to 1,073 K, ferropericlase containing 0, 5, 20% Fe, 8 14 1,273 K. We find...

Research Article| March 01, 2015 Why cold slabs stagnate in the transition zone Scott D. King; King 1Department of Geosciences, Virginia Tech, Blacksburg, 24061, USA2Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Germany Search for other works by this author on: GSW Google Scholar Daniel J. Frost; Frost 2Bayerisches David C. Rubie Geology (2015) 43 (3): 231–234. https://doi.org/10.1130/G36320.1 Article history received: 30 Sep 2014 rev-recd: 17 Dec accepted: 18 first online: 09 Mar...

Highly siderophile elements (HSEs) are strongly depleted in the bulk silicate Earth (BSE) but present near-chondritic relative abundances. The conventional explanation is that HSEs were stripped from mantle by segregation of metal during core formation added back proportions late accretion, after had ceased. Here we show metal-silicate equilibration and Earth’s actually increased HSE concentrations because partition coefficients relatively low at high pressures within Earth. pervasive...