Publications de Susannah McGregor Dorfman

Composition and Pressure Effects on Partitioning of Ferrous Iron in Iron-Rich Lower Mantle Heterogeneities

Marco Cantoni, Philippe Gillet, Farhang Nabiei, Susannah McGregor Dorfman, James Badro, Charles-Edouard Boukaré

Both seismic observations of dense low shear velocity regions and models of magma ocean crystallization and mantle dynamics support enrichment of iron in Earth’s lowermost mantle. Physical properties of iron-rich lower mantle heterogeneities in the modern ...

2021

Effects of composition and pressure on electronic states of iron in bridgmanite

Arnaud Magrez, Philippe Gillet, Susannah McGregor Dorfman

Electronic states of iron in the lower mantle's dominant mineral, (Mg,Fe,Al)(Fe,Al,Si)O-3 bridgmanite, control physical properties of the mantle including density, elasticity, and electrical and thermal conductivity. However, the determination of electroni ...

MINERALOGICAL SOC AMER2020

Carbonate stability in the reduced lower mantle

Marco Cantoni, Philippe Gillet, Farhang Nabiei, Susannah McGregor Dorfman, James Badro

2018

Primordial metallic melt in the deep mantle

Susannah McGregor Dorfman

Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp bo ...

Amer Geophysical Union2016

Electronic transitions of iron in almandine-composition glass to 91 GPa

Philippe Gillet, Susannah McGregor Dorfman

Valence and spin states of Fe were investigated in a glass of almandine (Fe3Al2Si3O12) composition to 91 GPa by X-ray emission spectroscopy and energy- and time-domain synchrotron Mossbauer spectroscopy in the diamond-anvil cell. Changes in optical propert ...

Mineralogical Soc Amer2016

Composition dependence of spin transition in (Mg,Fe)SiO3 bridgmanite

Philippe Gillet, Susannah McGregor Dorfman, James Badro

Spin transitions in (Mg,Fe)SiO3 bridgmanite have important implications for the chemistry and dynamics of Earth's lower mantle, but have been complex to characterize in experiments. We examine the spin state of Fe in highly Fe-enriched bridgmanite synthesi ...

Mineralogical Society of America2015

Strength and texture of Pt compressed to 63 GPa

Susannah McGregor Dorfman

Angle-and energy-dispersive X-ray diffraction experiments in a radial geometry were performed in the diamond anvil cell on polycrystalline platinum samples at pressures up to 63 GPa. Observed yield strength and texture depend on grain size. For samples wit ...

Amer Inst Physics2015

Effect of Fe-enrichment on seismic properties of perovskite and post-perovskite in the deep lower mantle

Susannah McGregor Dorfman

Recent experimental measurements of the equation of state of perovskites and post-perovskites in the (Mg,Fe)SiO3 and (Mg,Fe,Al)(Fe,Al,Si)O-3 systems over a wide range of iron contents are used to constrain the effects of Fe and Al on density and bulk modul ...

Oxford University Press2014

The strength of ruby from X-ray diffraction under non-hydrostatic compression to 68 GPa

Susannah McGregor Dorfman

Polycrystalline ruby (alpha-Al2O3:Cr3+), a widely used pressure calibrant in high-pressure experiments, was compressed to 68.1 GPa at room temperature under non-hydrostatic conditions in a diamond anvil cell. Angle-dispersive X-ray diffraction experiments ...

Springer2014

Effects of Fe-enrichment on the equation of state and stability of (Mg,Fe)SiO3 perovskite

Susannah McGregor Dorfman

Fe-rich natural orthopyroxenes with compositions of (Mg0.61Fe0.38Ca0.01)SiO3 (Fe#38) and (Mg0.25Fe0.74Ca0.01)SiO3 (Fe#74) were studied at pressures up to 155 GPa and temperatures up to 3000 K. Single-phase orthorhombic GdFeO3-type perovskite was synthesize ...

Elsevier Science Bv2013

Synthesis and equation of state of perovskites in the (Mg, Fe)(3)Al2Si3O12 system to 177 GPa

Susannah McGregor Dorfman

Natural and synthetic pyrope-almandine compositions from 38 to 100 mol% almandine (Alm38-Alm100) were studied by synchrotron X-ray diffraction in the laser-heated diamond anvil cell to 177 GPa. Single-phase orthorhombic GdFeO3-type perovskites were synthes ...

Elsevier Science Bv2012

Intercomparison of pressure standards (Au, Pt, Mo, MgO, NaCl and Ne) to 2.5 Mbar

Susannah McGregor Dorfman

We have performed a series of co-compression experiments on Au, Pt, Mo, MgO and NaCl to extend internally consistent pressure calibration and characterize shear strength of pressure media to 2.5 Mbar. Measured unit cell volumes of calibrants show differenc ...

Amer Geophysical Union2012