The genesis of the Llanrwst and Llanfair veinfields, North Wales; evidence from fluid inclusions and stable isotopes

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doi: 10.1017/S0016756897006729
Authors:Haggerty, R.; Bottrell, S. H.
Author Affiliations:Primary:
University of Leeds, Department of Earth Sciences, Leeds, United Kingdom
Volume Title:Geological Magazine
Source:Geological Magazine, 134(2), p.249-260. Publisher: Cambridge University Press, London, United Kingdom. ISSN: 0016-7568
Publication Date:1997
Note:In English. 44 refs.; illus., incl. 7 tables, sketch map
Summary:The Llanwrst Pb-Zn veinfield occupies fractures in an Ordovician volcano-sedimentary sequence, with three separate mineralizing events; the Llanfair Pb-Zn-Cu veinfield consists of sporadic mineralization in Silurian sediments. Fluid inclusion data from both veinfields indicate that mineralization took place from CaCl2-bearing brines, up to 26 wt.% NaCl eq., between 125 and 190°C with cooler (<<<[dollar]I> 100°C) more dilute fluids associated with later thrusting at Llanwrst. Sulphur at both veinfields was derived during the main phases of sulphide precipitation from the host rocks, with paragenetically late sulphides and sulphates deriving sulphur from Δ34S-enriched surface waters. For vein carbonates, Δ13C and Δ18O values show that both deposits formed from waters that had undergone extensive water-rock interaction; C was derived from at least two sources: marine carbonate dominated at Llanfair, whereas organic matter in the host rocks was more significant at Llanwrst. [R.A.H.]
Subjects:Alkaline earth metals; Brines; C-13/C-12; Calcium; Carbon; Faults; Fluid inclusions; Fractures; Hydrothermal alteration; Inclusions; Isotopes; Lead-zinc deposits; Metal ores; Metals; Metasomatism; Mineral deposits, genesis; O-18/O-16; Ordovician; Organic compounds; Oxygen; Paleozoic; S-34/S-32; Stable isotopes; Sulfur; Thrust faults; Water-rock interaction; Europe; Great Britain; United Kingdom; Wales; Western Europe; Hydrothermal processes; Llanfair veinfield; Llanrust veinfield; Northern Wales; Organic materials
Abstract Numbers:97M/3894
Record ID:1997042872
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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