The tectono-stratigraphic controls to mineralization in the Silvermines area, County Tipperary, Ireland

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Authors:Andrew, Colin J.
Author Affiliations:Primary:
Consult. Econ. Geol., Trim, Ireland
Tara Mines, Ireland
U. S. Borax, United States
Geol. Surv. Irel., Ireland
Volume Title:Geology and genesis of mineral deposits in Ireland
Volume Authors:Andrew, Colin J., editor; Crowe, R. W. A.; Finlay, S.; Pennell, W. M.; Pyne, J. F.
Source:Geology and genesis of mineral deposits in Ireland, edited by Colin J. Andrew, R. W. A. Crowe, S. Finlay, W. M. Pennell and J. F. Pyne, p.377-417. Publisher: Ir. Assoc. Econ. Geol., Dublin, Ireland. ISBN: 0-9509894-1-X
Publication Date:1986
Note:In English. 51 refs.; illus. incl. 2 tables, strat. col., sects., geol. sketch maps
Summary:Zn-Pb-Ba mineralization occurs in Courceyan transgressive siliciclastic rocks and overlying carbonates within the Silvermines fault zone, which was active during sedimentation and mineralization. Mineralization occurs in hydraulic fracture zones and as epigenetic replacements within Lower Palaeozoic greywackes and basal Carboniferous clastics. The upper orebody is a tabular, stratiform, irregular lens of massive baryte, siderite, marcasite and pyrite with variable amounts of base-metal sulphides of syngenetic character. Genetically the Silvermines deposits are of sedimentary exhalative origin. Convective mineralizing fluids were derived from the Lower Palaeozoic basement at approx 220°C and at salinities of 10-15 wt.% NaCl equiv. At high levels these were mixed with formational waters (20°C, 25 wt.% NaCl equiv.) derived from Carboniferous sea-water. Mixing led to rapid and sometimes explosive boiling, followed by precipitation of the lower, epigenetic orebodies. The upper orebody was due to debouching of the mixed brines onto the seafloor, followed by lateral migration to palaeotopographic lows between Waulsortian mudbanks. [R.E.]
Subjects:Brecciation; Caledonian Orogeny; Carboniferous; Dinantian; Economic geology; Experimental studies; Fault zones; Fluid inclusions; Geologic thermometry; Hydrothermal alteration; Iapetus; Inclusions; Lead-zinc deposits; Lenses; Massive deposits; Metal ores; Metals; Metasomatism; Mineral deposits, genesis; Mineralization; Ore-forming fluids; Paleosalinity; Paleozoic; Polymetallic ores; Precious metals; Silver ores; Stratiform deposits; Stratigraphic controls; Structural controls; Sulfides; Veins; Europe; Ireland; Western Europe; Hydrothermal processes; Silvermines District
Abstract Numbers:87M/5702
Record ID:1989073845
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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