Title Information
Title
GEOCHEMISTRY OF THE GALÁPAGOS ARCHIPELAGO: UNRAVELING DEEP MANTLE SIGNATURES FROM THE INFLUENCE OF SHALLOW LEVEL PROCESSES
Name: Personal
Name Part
Peterson, Mary E
Role
Role Term: Text
creator
Origin Information
Copyright Date
2015
Physical Description
Extent
xiii, 313 p.
digitalOrigin
born digital
Note
Thesis (Ph.D. -- Brown University (2015)
Name: Personal
Name Part
Saal, Alberto
Role
Role Term: Text
Director
Name: Personal
Name Part
Kurz, M
Role
Role Term: Text
Reader
Name: Personal
Name Part
Parman, Stephen
Role
Role Term: Text
Reader
Name: Personal
Name Part
Forsyth, Donald
Role
Role Term: Text
Reader
Name: Personal
Name Part
Cooper, Reid
Role
Role Term: Text
Reader
Name: Corporate
Name Part
Brown University. Geological Sciences
Role
Role Term: Text
sponsor
Genre (aat)
theses
Abstract
In this dissertation, I present a large geochemical data set of submarine glass, melt inclusions and whole rock collected from across the Galapagos Archipelago to explore the influence of shallow level processes on lavas erupted at the surface and to isolate deep mantle signatures of the plume. The first chapter examines the ghost plagioclase signature using Pb isotope analyses of melt inclusions collected from the Islands of Fernandina and Santiago [published in Journal of Petrology. 55(11), 2193-2216]. The measurement of Pb-isotopes on melt-inclusions from Fernandina and Santiago show the ghost plagioclase signature is best explained by contamination in the present-day crust, over an ancient recycled mantle source. The second chapter measures 118 submarine glasses from across the Galapagos Archipelago for major, trace, isotopic and volatile contents [manuscript submitted to Journal of Petrology April 2015]. After evaluating the effects of shallow level processes, H2O/Ce and F/Nd were found to best distinguish different isotopic end-members. The Fernandina end-member possesses a higher water content than the depleted upper mantle, as well as high C/3He ratios, showing this end-member to be carbonated as well as wet. The third chapter uses μ-XANES measurements of Fe+3/ΣFe (a proxy for fO2) on a subset of samples characterized in Chapter 2. Crystal fractionation and assimilation increases, while S degassing decreases Fe+3/ΣFe ratios. After accounting for these shallow level processes, the Fernandina component is found to be the most oxidized isotopic end-member in the Galapagos. The fourth chapter presents new stable oxygen isotope analyses for olivines collected across the Galapagos Archipelago. Variations in δ18O (~ +4.7‰ – +5.4‰) fall outside the expected value for the upper mantle. However, the δ18O values of the isotopic end-members are within error of the upper mantle range. This shows the homogeneity in δ18O of the Galapagos plume mantle and indicates variations outside this value are due to assimilation of shallow level material. This is consistent with observed correlations between δ18O values and Sr/Sr* and Ba/Nb ratios.
Subject
Topic
Galapagos
Subject
Topic
hotspot
Subject
Topic
mantle
Subject
Topic
volatile elements
Subject
Topic
lead isotopes
Subject
Topic
oxygen isotopes
Subject
Topic
oxygen fugacity
Subject
Topic
oxidation state
Subject
Topic
shallow level process
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/994566")
Topic
Lead--Isotopes
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1049623")
Topic
Oxygen--Isotopes
Subject (FAST) (authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1219610")
Geographic
Galapagos Islands
Record Information
Record Content Source (marcorg)
RPB
Record Creation Date (encoding="iso8601")
20150601
Language
Language Term: Code (ISO639-2B)
eng
Language Term: Text
English
Identifier: DOI
10.7301/Z0WH2NCV
Access Condition: rights statement (href="http://rightsstatements.org/vocab/InC/1.0/")
In Copyright
Access Condition: restriction on access
Collection is open for research.
Type of Resource (primo)
dissertations