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.
","abstract_html":"<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>","abstract_has_math":false,"creators":["Hoffmann, Trevor"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Jeremy Deans","Mark Puckett","Andrew Martin"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-05-01T07:00:00Z","date_published":"2024-05-01T07:00:00Z","updated_at":"2026-07-24T05:45:47Z","subjects":["Amphibole","sulfide","dikelet","oceanic core complexes","mid-ocean ridges","oceanic lithosphere","Geochemistry","Geology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://aquila.usm.edu/masters_theses/1021","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Jeremy Deans","Mark Puckett","Andrew Martin"]},{"key":"dc:creator","label":"Author","values":["Hoffmann, Trevor"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2024-01-01T08:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Amphibole","sulfide","dikelet","oceanic core complexes","mid-ocean ridges","oceanic lithosphere","Geochemistry","Geology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://aquila.usm.edu/masters_theses/1021"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["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"]}]}],"canonical_facts":{"dc:contributor":["Jeremy Deans","Mark Puckett","Andrew Martin"],"dc:creator":["Hoffmann, Trevor"],"dc:date.available":["2024-01-01T08:00:00Z"],"dc:description.abstract":["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.
"],"dc:identifier":["https://aquila.usm.edu/masters_theses/1021"],"dc:subject":["Amphibole","sulfide","dikelet","oceanic core complexes","mid-ocean ridges","oceanic lithosphere","Geochemistry","Geology"],"dc:title":["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"],"thesis:degree_level":["Masters Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T05:45:47Z"}