The Timing of Vein Hosted Copper Mineralization and its Structural Setting in The Upper Paleozoic Sedimentary Rocks of Southwest Ireland

Lang, Jürgen; Meere, Patrick A.; Unitt, Richard P.; Selby, David

Abstract

This study provides a new insight into the genetic and chronological development of the vein hosted copper sulfide mineralization in the Late Paleozoic Munster Basins of SW Ireland. Field mapping, supported by drone photogrammetry, petrography, microthermometry and geochronology of selected historic mining sites in West Cork reveal elementary data for a reinterpretation of the mineralization processes. Structural investigations define two distinct ore forming episodes: The initial vein precipitation is directly related to syn-basinal, extensional E-W to ENE-WSW striking normal faults. Smaller sediment hosted Cu sulfide occurrences are related to the extensional fault systems. The second mineralization phase occurred during the early stage of the late Carboniferous Variscan compression by reactivation of early extensional, basinal fault systems. Copper mineralization related molybdenite samples from the historical Ballycummisk Mines on Mizen Peninsula produced Re-Os dates of 315.5 ± 1.6 Ma and 311.8 ± 1.6 28 Ma. This Pennsylvanian (Upper) Carboniferous sulfide emplacement is related to this second stage, syn-Variscan compressional mineralization event. The discovery of the two distinct Cu mineralizing events in SW Ireland provides an important contribution to the understanding of the development of the Irish Ore Field including the Pb-Zn Midlands Deposits.

Citation

Lang, J., Meere, P. A., Unitt, R. P., & Selby, D. (online). The Timing of Vein Hosted Copper Mineralization and its Structural Setting in The Upper Paleozoic Sedimentary Rocks of Southwest Ireland. Journal of the Geological Society, https://doi.org/10.1144/jgs2024-180

• Journal Article Type: Article
• Acceptance Date: Feb 14, 2025
• Online Publication Date: Feb 20, 2025
• Deposit Date: Feb 17, 2025
• Publicly Available Date: Feb 26, 2025
• Journal: Journal of the Geological Society
• Print ISSN: 0016-7649
• Electronic ISSN: 2041-479X
• Publisher: The Geological Society
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1144/jgs2024-180
• Keywords: copper mineralization, SW Ireland, Variscan, Munster Basin, Re-Os geochronology, fluid inclusions
• Public URL: https://durham-repository.worktribe.com/output/3488316