A Caltech Library Service

Magmatic Differentiation in Arc and Mid Ocean Ridge Settings


Lewis, Madeline Janine (2021) Magmatic Differentiation in Arc and Mid Ocean Ridge Settings. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/a1ky-ab66.


The compositional variation of igneous rocks and construction of Earth's crust is the result of magmatic differentiation -- crystallization, melting, and assimilation mechanisms that cause the composition of magmas to change over time. This thesis investigates magma generation and evolution at both convergent and divergent plate boundaries. The resulting magmatic arcs and mid-ocean ridges create the vast majority of Earth's crust, though the details of crustal construction and the specific processes that generate the observed magmatic and volcanic products are complex. Accordingly, this work uses the geochemical signatures encoded in rocks and minerals to explain magmatic differentiation histories in multiple tectonic settings.

Here, I present five main studies that utilize field and textural observations, geochemical analyses, and computational modeling to investigate the compositional structure of the crust beneath magmatic arcs and mid-ocean ridges. In addition, this work explores the pyroclastic and sedimentary products dispersed by magmatically heated hydrothermal fluids in submarine environments. Chapters 2 and 3 investigate the crystallization histories of mafic intrusions in the eastern-central Sierra Nevada batholith paleo-continental arc, California. This work has implications for the compositional and temporal generation of both mafic and evolved magmas throughout the batholith and in other continental arcs. Chapters 4 and 5 explore records of submarine volcanic ash deposits associated with explosive mid-ocean ridge eruptions from the East Pacific Rise and Pacific-Antarctic Ridge, as well as the effects that sea level change has on melting of the mantle, eruption styles, and the compositional evolution of mid-ocean ridge magmas. Chapter 6 examines the mineral hosting of rare earth elements (REEs) in the Wadi Karim banded iron formation, and the implications of element mobility on interpretations based on REE abundances.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Magma; geochemistry; petrology; geochronology; magmatic arc; mid-ocean ridge; differentiation; volcano; iron formation
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Geochemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bucholz, Claire E. (co-advisor)
  • Asimow, Paul David (co-advisor)
Thesis Committee:
  • Rossman, George Robert (chair)
  • Fischer, Woodward W.
  • Stolper, Edward M.
  • Bucholz, Claire E.
  • Asimow, Paul David
Defense Date:18 May 2021
Funding AgencyGrant Number
AGeS2, via NSFEAR-1759200
NSFEAR- 1551433
Record Number:CaltechTHESIS:06022021-034345855
Persistent URL:
Related URLs:
URLURL TypeDescription
https://doi. org/10.1029/2017GC007341DOIArticle adapted for Chapter 4
Lewis, Madeline Janine0000-0001-7968-2822
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14229
Deposited By: Madeline Lewis
Deposited On:03 Jun 2021 18:46
Last Modified:10 Jun 2021 15:48

Thesis Files

[img] PDF (Thesis-full version) - Final Version
See Usage Policy.

[img] PDF (Thesis-compressed version) - Final Version
See Usage Policy.

[img] MS Excel (Chapters 2-6) - Supplemental Material
See Usage Policy.


Repository Staff Only: item control page