Project title: Irish Pb-Zn Mineral Deposits: Stonepark, Tobermalug, Pallas Green, etc. in Co. Limerick
Researcher: Dr Paul Slezak
Purpose: The Pallas Green, Stonepark, and other Zn prospects in the SW Irish orefield, located in Co. Limerick, are atypical among Irish base metal deposits as they are spatially associated with alkaline volcanic units: the Knockroe and Knockseefin volcanics. These igneous units are approximately Viséan age and may have affected the ore tenor. However, only minor amounts of research have focussed on these units as part of the stratigraphy of Ireland and the nature of their eruption, but no in-depth study has been undertaken to examine their origins and tectonic implications, which could impact mineral deposit type and therefore exploration methods.
Hypothesis: Preliminary analyses (this study) show these units are alkaline and back arc continental or ocean island basal signature, but this needs to be verified isotopically and has tectonic implications for Ireland and the UK. There are two volcanic units (Knockroe and Knockseefin, the latter of which is younger: is this unit different chemically and temporally? The volcanic units are altered to chlorite + carbonate. Is this a function of seawater related to submarine volcanism, or are other fluids (hydrothermal, ore-bearing, etc.) also involved with this alteration? If so, is it chemically distinguishable and can we use this for future mineral exploration? Lastly, deep-seated structures that are commonly associated with Irish-type deposits are difficult to recognise in seismic surveys in the SW Irish orefield, which may be in part due to the presence of the volcanic rocks. Examining the location, morphology, nature, and properties (physical and geochemical) of the volcanic units may help resolve some of the seismic imaging issues.
1) Define bulk-rock geochemistry, isotope chemistry, and physical properties to determine origins and tectonic setting.
2) Characterise alteration and determine source. Quantify alteration, especially in mineralised areas, using mass balance and other metrics. Make available to industry.
3) Identify and conduct radiogenic dating on mineral phases (e.g. apatite, baddeleyite, etc.), if present.
4) Determine geochemistry of ore minerals for comparison with other Irish-type deposits.