The Effects of Amphibole- and Sulfide-Producing Melts on Crustal Strength in Gabbros of Lower Oceanic Crust in Oceanic Core Complexes, Mid-Atlantic and Southwest Indian Ridges

<p>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.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2024

Author dc:creator

• Hoffmann, Trevor

Contributors dc:contributor

• Jeremy Deans
• Mark Puckett
• Andrew Martin

• Amphibole
• sulfide
• dikelet
• oceanic core complexes
• mid-ocean ridges
• oceanic lithosphere
• Geochemistry
• Geology

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/1021

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-2122