Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp01sx61dm312
 Title: Effects of Iron Enrichment on Chemistry and Physical Properties of Deep Lower Mantle Silicates Authors: Dorfman, Susannah Advisors: Duffy, Thomas S Contributors: Geosciences Department Subjects: GeophysicsMineralogy Issue Date: 2012 Publisher: Princeton, NJ : Princeton University Abstract: Variations in seismic wave speed and density in the Earth's deep lower mantle have been linked to chemical heterogeneities. In order to identify the compositions of these regions and determine their roles in Earth history and dynamics, experimental measurements are needed of the effects of compositional variation, particularly major elements Fe and Al, on phase equilibria and physical properties of mantle minerals. The experiments that comprise this dissertation provide new constraints on the chemistry and compressibility of mantle silicates. Experiments were conducted at mantle pressure-temperature conditions using the laser-heated diamond anvil cell. Determination of pressure in the diamond anvil cell requires internal pressure calibrants which suffer from uncertainty as high as 10\% at Mbar pressures. A series of experiments were performed to test the reliability and agreement of pressure scales for Au, Mo, MgO, NaCl B2, Ne and Pt. These data were used to determine a new comprehensive pressure scale for use in experiments on mantle materials. The lower mantle's dominant phase is (Mg,Fe,Al)(Fe,Al,Si)O$_3$ perov\-skite. At pressure-temperature conditions comparable to the deep lower mantle, perovskite undergoes a transition to a post-perovskite phase. I synthesized perovskites and post-perovskites from a series of Fe-rich (enstatite--ferrosilite, (Mg$_{1-x}$,Fe$_x$)SiO$_3$, \$0