Date of Award


Degree Type

Masters Thesis

Degree Name

Master of Science (MS)


Biological, Environmental, and Earth Sciences

Committee Chair

Jeremy Deans

Committee Chair School

Biological, Environmental, and Earth Sciences

Committee Member 2

Mark Puckett

Committee Member 2 School

Biological, Environmental, and Earth Sciences

Committee Member 3

Andrew Martin


This study investigates gabbro-cored oceanic core complexes in the slow-spreading Mid-Atlantic Ridge (MAR) and the ultraslow spreading Southwest Indian Ridge (SWIR). Dikelets are a texture found in thin section samples from these systems that form as a result of crystal-plastic deformation. Thin section samples from the Atlantis Massif, MARK Area, and 13˚-15˚ North of the MAR and the Atlantis Bank of the SWIR were observed with petrography to find these dikelets and identify what type of dikelet is present. SEM-EDS is used to identify the mineral assemblages present in the dikelets. LA-ICP-MS is used on amphibole to determine if its origin is igneous or metamorphic. The temperature of formation was calculated for amphibole and estimated for sulfides. Ferro-hornblende is the dominant amphibole observed in dikelets from the MAR. Pyrite is the common Fe sulfide found in dikelets, while chalcopyrite was the Cu-Fe sulfide found in sulfide-rich dikelets, although its presence was quite rare. Temperature calculations for amphibole suggested that amphibole shown is a secondary amphibole (metamorphic), while temperature estimations for sulfides suggest that they formed from a late-stage melt. Trace element data shows both igneous and metamorphic amphibole are observed in Atlantis Massif.