Date of Award

2026

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Specialization

Geological Oceanography

Department

Oceanography

First Advisor

Katherine Kelley

Abstract

Plume-influenced spreading centers preserve critical insights into mantle domain interactions, yet resolving localized volatile (e.g., H2O and CO2) heterogeneities is often limited by coarse ridge-axis sampling. Here, we present a new high-resolution geochemical dataset for the juvenile Gulf of Aden spreading center, analyzing 36 previously unstudied ridge-axis glass samples from 17 segments along the Sheba Ridge. By accounting for segment-specific crystallization trends, we constrain primary melt and mantle source H2O contents, revealing previously unresolved regional variations. Most notably, primary melt compositions and models of mantle source composition show H2O enrichment coincident with the peak influence of the Afar plume on the spreading center at ~46°E, as shown by prior studies, but also reveal distinct, moderately hydrous regions between 48-50°E, and ~53°E. The 48-50°E region displays elevated K2O/H2O ratios (0.3-0.5). Elevated volatiles are not exclusively associated with isotopic enrichment (e.g., 206Pb/204Pb) or other recognized plume signatures (e.g., La/Sm), suggesting a distinct enriched, hydrous mantle domain. Where the plume influence is the strongest, models of the melt fraction (F) and the water content of the mantle (H2O-0) demonstrate that higher H2O-0 contents are associated with lower F across the western domain, indicating a deep, damp flux-melting regime. Crucially, volatile enrichments and other plume-related signatures extend laterally over 470 km within the Gulf of Aden, but modeled mantle melting temperatures remain uniform and low (1375-1475°C), demonstrating a spatial decoupling between the thermal and chemical components of the upwelling plume.

Download

Available for download on Sunday, September 10, 2028

Share

COinS