Year: 2023
Type: conference-paper
Abstract: The Rathdowney Trend in south-central Ireland, is a NE-SW trend of fault-controlled Zn-Pb deposits that includes the Galmoy and Lisheen orebodies. The deposits are broadly stratabound and flat-lying occurring at or near the base of the Waulsortian Limestone Formation - a 200m thick massive biomicrite that is regionally dolomitised. The ore is largely developed by replacement of a dark, hydrothermal dolomite and dolomitic breccia - the black matrix breccia that is intimately associated with the mineralization event. Faulting exerts a major control on the ore thickness and distribution. The largest structures provided conduits for hot, metal-bearing fluids from basement to enter the Waulsortian at discrete feeder zones. Metal distribution patterns indicate that fluids progressed northwards from these feeder zones, facilitated by a network of small-displacement, low-angle extensional structures developed at the base Waulsortian contact with the underlying Ballysteen Formation. Significant dissolution of carbonate by hydrothermal fluids was important in developing conduits and promoting fluid flow. Fluid inclusion and isotope studies indicate that mineralization resulted from the mixing of hot, metal-bearing fluids with colder, saline fluids bearing sulphur derived from the bacteriogenic reduction of Carboniferous seawater sulphate. Mineralization developed during growth of the fault systems associated with basin development. Hydrothermal activity initiated shortly after rifting commenced during mid to late-Waulsortian sedimentation.
DOI: 10.61153/xlpo1941
Language: English
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4386743397