VOLATILES IN MANTLE SOURCES AT MID-OCEAN RIDGE AND INTRAPLATE SETTINGS

Author

• Rebecca Lippitt, University of Rhode IslandFollow

Date of Award

2026

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Oceanography

Specialization

Geological Oceanography

Department

Oceanography

First Advisor

Katherine A. Kelley

Abstract

Volatiles play an integral role in upper mantle processes and the eruptive styles of volcanoes. Although we know the importance of volatiles to volcanic systems, processes like melting, crystallization, and degassing alter the volatile abundances of mantle melts, making it difficult to quantify mantle source compositions and the extent to which volatiles influence melting processes. Additionally, volatile content may be a key factor in setting the oxidation conditions of mantle source rocks and subsequently changing those conditions in a body of magma as it ascends through the crust and is erupted at the Earth’s surface. Recent work, however, has identified small suites of lavas and melt inclusions determined to be CO₂-undersaturated, which may preserve mantle conditions less impacted by crystallization and degassing. In this dissertation, I will investigate differences in volatile concentrations among mantle sources at mid-ocean ridge and intraplate settings, as well as the role volatiles play in driving mantle melting and controlling magmatic redox conditions by (1) analyzing a collection of possibly CO₂-undersaturated mid-ocean ridge basalt melt inclusions to constrain carbon in mantle sources at various localities along the ridge system, (2) tracking sulfur concentrations and Fe³⁺/SFe ratios of submarine lavas erupted over a large range of water depths to test the hypothesis that sulfur degassing drives the reduction of ocean island basalts, and (3) testing the relationships between volatile contents and other geochemical and physical characteristics of magmas in the Revillagigedo Archipelago, to evaluate compositional changes in mantle sources and conditions to determine a mechanism for continued, volatile-rich intraplate volcanism. Together, this body of work provides valuable insights that broaden constraints on the degree of heterogeneity of volatiles in the upper mantle and how they contribute to and influence resulting magmatism.

Recommended Citation

Lippitt, Rebecca, "VOLATILES IN MANTLE SOURCES AT MID-OCEAN RIDGE AND INTRAPLATE SETTINGS" (2026). Open Access Dissertations. Paper 4606.
https://digitalcommons.uri.edu/oa_diss/4606