Show simple item record

dc.contributor.authorMcFarlane, Elisabeth Ann.
dc.creatorMcFarlane, Elisabeth Ann.en_US
dc.date.accessioned2011-10-31T18:14:13Z
dc.date.available2011-10-31T18:14:13Z
dc.date.issued1994en_US
dc.identifier.urihttp://hdl.handle.net/10150/186611
dc.description.abstractThe Earth may have been covered with a terrestrial magma ocean. Is there evidence for resulting extensive mineral fractionation? Agee and Walker, 1988, proposed that significant flotation and addition of olivine into the upper mantle can explain the elevated Mg/Si ratio of this region. A number of element ratios were present in the primitive mantle of the Earth in approximately chondritic ratios (e.g., Jagoutz et al., 1979) providing constraints on amounts of mineral fractionation if appropriate partition coefficient values are known (e.g., Kato et al., 1988a). In addition, the V, Cr and Mn abundance pattern in the mantles of the Earth and moon are similar to one another, which could imply a related origin for these bodies (e.g., Ringwood, 1990). Previous attempts to explain the origin of this abundance pattern have been unsuccessful (e.g., Drake et al., 1989). High pressure and temperature mantle mineral/silicate melt partition coefficient values are experimentally determined in this work. These values are used via equilibrium crystallization to examine the effect of mineral fractionation on the primitive mantle. The effect of mineral fractionation on the abundance pattern of V, Cr and Mn in the upper mantle of the Earth is examined. Fractionation of majorite garnet, magnesiowustite and Mg-perovskite yields a V, Cr and Mn abundance pattern that is different than inferred. Thus, the pattern of V, Cr and Mn was not established by high pressure mantle mineral/silicate melt fractionation. Other mineral fractionation effects are also examined. Significant addition of olivine to the upper mantle is disallowed based on the Ni/Co ratio. Significant fractionation of majorite garnet, magnesiowustite and Mg-perovskite is precluded based on several element ratios (e.g., Mg/Al, Ca/Al for majorite garnet; e.g., Mg/Al, Ca/Al, Mg/Si, Mg/Ca for magnesiowustite; e.g., Ca/Al, Sc/Sm, Mg/Ca for Mg-perovskite). Thus, the primitive mantle does not show evidence of significant fractionation of volumetrically important liquidus phases. The implication is that the Earth's Mg/Si ratio unique, and that compositionally distinct reservoirs of material were largely preserved in the accretionary environment.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectDissertations, Academic.en_US
dc.subjectGeology.en_US
dc.subjectGeochemistry.en_US
dc.subjectMineralogy.en_US
dc.titleDifferentiation in the early Earth: An experimental investigation.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.contributor.chairDrake, Michael J.en_US
dc.identifier.oclc722419758en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberBoynton, Williamen_US
dc.contributor.committeememberSwindle, Timothyen_US
dc.contributor.committeememberPatchett, Jonathanen_US
dc.contributor.committeememberRuiz, Joaquinen_US
dc.identifier.proquest9424944en_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
dc.description.noteThis item was digitized from a paper original and/or a microfilm copy. If you need higher-resolution images for any content in this item, please contact us at repository@u.library.arizona.edu.
dc.description.admin-noteOriginal file replaced with corrected file April 2023.
refterms.dateFOA2018-09-03T10:03:04Z
html.description.abstractThe Earth may have been covered with a terrestrial magma ocean. Is there evidence for resulting extensive mineral fractionation? Agee and Walker, 1988, proposed that significant flotation and addition of olivine into the upper mantle can explain the elevated Mg/Si ratio of this region. A number of element ratios were present in the primitive mantle of the Earth in approximately chondritic ratios (e.g., Jagoutz et al., 1979) providing constraints on amounts of mineral fractionation if appropriate partition coefficient values are known (e.g., Kato et al., 1988a). In addition, the V, Cr and Mn abundance pattern in the mantles of the Earth and moon are similar to one another, which could imply a related origin for these bodies (e.g., Ringwood, 1990). Previous attempts to explain the origin of this abundance pattern have been unsuccessful (e.g., Drake et al., 1989). High pressure and temperature mantle mineral/silicate melt partition coefficient values are experimentally determined in this work. These values are used via equilibrium crystallization to examine the effect of mineral fractionation on the primitive mantle. The effect of mineral fractionation on the abundance pattern of V, Cr and Mn in the upper mantle of the Earth is examined. Fractionation of majorite garnet, magnesiowustite and Mg-perovskite yields a V, Cr and Mn abundance pattern that is different than inferred. Thus, the pattern of V, Cr and Mn was not established by high pressure mantle mineral/silicate melt fractionation. Other mineral fractionation effects are also examined. Significant addition of olivine to the upper mantle is disallowed based on the Ni/Co ratio. Significant fractionation of majorite garnet, magnesiowustite and Mg-perovskite is precluded based on several element ratios (e.g., Mg/Al, Ca/Al for majorite garnet; e.g., Mg/Al, Ca/Al, Mg/Si, Mg/Ca for magnesiowustite; e.g., Ca/Al, Sc/Sm, Mg/Ca for Mg-perovskite). Thus, the primitive mantle does not show evidence of significant fractionation of volumetrically important liquidus phases. The implication is that the Earth's Mg/Si ratio unique, and that compositionally distinct reservoirs of material were largely preserved in the accretionary environment.


Files in this item

Thumbnail
Name:
azu_td_9424944_sip1_c.pdf
Size:
20.48Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record