Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity
Jackson, Matthew G.
MetadataShow full item record
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.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2008
Suggested CitationThesis: Jackson, Matthew G., "Dismantling the deep earth : geochemical constraints from hotspot lavas for the origin and lengthscales of mantle heterogeneity", 2008-02, DOI:10.1575/1912/2217, https://hdl.handle.net/1912/2217
Showing items related by title, author, creator and subject.
Li, Weichang (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006-02)This thesis develops methods for estimating wideband shallow-water acoustic communication channels. The very shallow water wideband channel has three distinct features: large dimension caused by extensive delay spread; ...
Austin, James A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1978-12)The results of a detailed geophysical investigation conducted by the Woods Hole Oceanographic Institution in 1975 have been used in conjunction with other available information to reconstruct the geologic history of ...
Air-sea interaction at contrasting sites in the eastern tropical Pacific : mesoscale variability and atmospheric convection at 10°N Farrar, J. Thomas (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-02)The role of ocean dynamics in driving air-sea interaction is examined at two contrasting sites on 125°W in the eastern tropical Pacific Ocean using data from the Pan American Climate Study (PACS) field program. Analysis ...