Microanalysis of sulphide rims: desulphurisation, latestage oxidation, and possible effects on PGE formation in chromite seams of the Rum layered intrusion, Scotland

Pentland, Kimberley (2026) Microanalysis of sulphide rims: desulphurisation, latestage oxidation, and possible effects on PGE formation in chromite seams of the Rum layered intrusion, Scotland. MSc(R) thesis, University of Glasgow.

Abstract

A sample derived from the chromite seam of the Unit 7-8 boundary of the Rum layered intrusion (Scotland) was studied to investigate enriched rims within base-metal sulphides (BMS). Two separate data sets were derived from the sample. The exposure data set calibrated and optimised SEM-EDS acquisition and addressed fundamental questions regarding ‘what makes good quality data’ for effective machine learning (ML), and highlighted the effectiveness of ML for micro-analysis. Analysis techniques involved Poisson noise scaling, factor analysis (FA), and hierarchical density-based clustering algorithm (HDBSCAN). Results indicated that the optimum number of average counts per pixel lies ~ 1200. The mineralogical data set addressed elemental changes across the BMS and explored their origins, aiding understanding of magmatic formation and corroborating a proposed secondary process to account for features observed (rims, oxides, platinum group minerals/metals). Analysis techniques involved SEM-imaging, SEM-EDS data, TEM-imaging, EELS analysis, ML algorithms (FA, HDBCAN), and stoichiometry calculations. Results displayed that the main change occurring within the enriched rims is that of sulphur loss, with mineral formulae displaying a change from Cu-S rich chalcopyrite to Cu-enriched S-poor chalcocite/digenite, accompanied by spatially complementary magnetite. These results indicated that the intrusive suite underwent a period of sulphur-degassing post emplacement, under low-temperature, low fluid-rock, oxidative conditions. Spatial observations regarding PGM grains within sulphidesilicate mineral boundaries with high proximity to Fe-oxides additionally indicated that the proposed processes of alteration could be a catalyst for PGM formation.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: Q Science > QE Geology
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
• Supervisor's Name: Einsle, Dr. Joshua Franz and Neill, Dr. Iain
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-85876
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 16 Apr 2026 15:56
• Last Modified: 16 Apr 2026 15:56
• Thesis DOI: 10.5525/gla.thesis.85876
• URI: https://theses.gla.ac.uk/id/eprint/85876