2026-09-20T00:39:02Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/431572022-01-14T19:34:50Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Stanley R. Hart.
Jackson, Matthew G. (Matthew Gerald)
Woods Hole Oceanographic Institution.
Joint Program in Oceanography
Woods Hole Oceanographic Institution
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
2008-11-07T19:10:03Z
2008-11-07T19:10:03Z
2008
2008
http://hdl.handle.net/1721.1/43157
248620722
Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2008.
Includes bibliographical references (p. 135-140).
Chapter 1 presents the first published measurements of Sr-isotope variability in olivine-hosted melt inclusions. Melt inclusions in just two Samoan basalt hand samples exhibit most of the total Sr-isotope variability observed in Samoan lavas. Chapter 3 deals with the largest possible scales of mantle heterogeneity, and presents the highest magmatic 3He/4He (33.8 times atmospheric) discovered in Samoa and the southern hemisphere. Along with Samoa, the highest 3He/4He sample from each southern hemisphere high 3He/4He hotspot exhibits lower 143Nd/144Nd ratios than their counterparts in the northern hemisphere. Chapter 2 presents geochemical data for a suite of unusually enriched Samoan lavas. These highly enriched Samoan lavas have the highest 87Sr/86Sr values (0.72163) measured in oceanic hotspot lavas to date, and along with trace element ratios (low Ce/Pb and Nb/U ratios), provide a strong case for ancient recycled sediment in the Samoan mantle. Chapter 4 explores whether the eclogitic and peridotitic portions of ancient subducted oceanic plates can explain the anomalous titanium, tantalum and niobium (TITAN) enrichment in high 3He/4He ocean island basalts (OIBs). The peridotitic portion of ancient subducted plates can contribute high 3He/4He and, after processing in subduction zones, a refractory, rutile-bearing eclogite may contribute the positive TITAN anomalies.
by Matthew G. Jackson.
Ph.D.
149 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
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http://dspace.mit.edu/handle/1721.1/7582
Earth, Atmospheric, and Planetary Sciences.
Joint Program in Oceanography.
Woods Hole Oceanographic Institution.
Submarine geology
Ophiolites
Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity
Thesis
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<Abstract>Chapter 1 presents the first published measurements of Sr-isotope variability in olivine-hosted melt inclusions. Melt inclusions in just two Samoan basalt hand samples exhibit most of the total Sr-isotope variability observed in Samoan lavas. Chapter 3 deals with the largest possible scales of mantle heterogeneity, and presents the highest magmatic 3He/4He (33.8 times atmospheric) discovered in Samoa and the southern hemisphere. Along with Samoa, the highest 3He/4He sample from each southern hemisphere high 3He/4He hotspot exhibits lower 143Nd/144Nd ratios than their counterparts in the northern hemisphere. Chapter 2 presents geochemical data for a suite of unusually enriched Samoan lavas. These highly enriched Samoan lavas have the highest 87Sr/86Sr values (0.72163) measured in oceanic hotspot lavas to date, and along with trace element ratios (low Ce/Pb and Nb/U ratios), provide a strong case for ancient recycled sediment in the Samoan mantle. Chapter 4 explores whether the eclogitic and peridotitic portions of ancient subducted oceanic plates can explain the anomalous titanium, tantalum and niobium (TITAN) enrichment in high 3He/4He ocean island basalts (OIBs). The peridotitic portion of ancient subducted plates can contribute high 3He/4He and, after processing in subduction zones, a refractory, rutile-bearing eclogite may contribute the positive TITAN anomalies.</Abstract>
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