Post-magmatic hydrothermal circulation and the origin of base metal mineralization, Cornwall, UK

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doi: 10.1144/jgs.157.3.589
Authors:Gleeson, S. A.; Wilkinson, J. J.; Shaw, H. F.; Herrington, R. J.
Author Affiliations:Primary:
Imperial College, T.H. Huxley School of Environment, Earth Sciences and Engineering, London, United Kingdom
Other:
Natural History Museum, United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.157(Part 3), p.589-600. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2000
Note:In English. 41 refs.; illus., incl. 1 table, geol. sketch maps
Summary:A detailed fluid-inclusion study of post-Variscan quartz ± carbonate ± sulphide ± anhydrite ± fluorite veins hosted by Palaeozoic basement (Porthleven, Menheniot, Cornwall) and Permo-Triassic sediments (Western Approaches Basin) has identified two broad fluid types. A high salinity (20-27 wt% NaCl), low temperature (80-150°C) brine is present in base metal mineralized veins hosted by Palaeozoic rocks onshore and in sulphate-bearing veins within the Permo-Triassic offshore succession. Microthermometric data indicate that saline fluids found in the Permo-Triassic basinal sequences have similar compositions to the base metal mineralizing fluids and confirms that such basins are likely sources for the mineralizing fluids. A second, hotter (200°C) more dilute (0-5 wt%) fluid has been identified in fault-hosted east-west-trending veins in the Porthleven area. It is likely that the temperatures of both the dilute and saline fluids have been affected by the local high heat producing Cornubian granite batholith. There is also limited evidence for fluid mixing of these two fluids which may have been responsible for base metal precipitation.
Sections:Geochemistry
Subsections:Minerals and ores
Subjects:Anhydrite; Antimony ores; Barite deposits; Base metals; Batholiths; Brines; Carbonates; Faults; Fluid inclusions; Fluorides; Fluorite; Framework silicates; Gold ores; Granites; Halides; Hydrothermal alteration; Igneous rocks; Inclusions; Intrusions; Iron ores; Lead ores; Low temperature; Lower Triassic; Mesozoic; Metal ores; Metasomatism; Microthermometry; Mineral deposits, genesis; Mineralization; Ore-forming fluids; Paleozoic; Permian; Plutonic rocks; Quartz; Salinity; Silica minerals; Silicates; Structural controls; Sulfates; Sulfides; Temperature; Triassic; Upper Permian; Uranium ores; Veins; Atlantic Ocean; Cornwall England; England; English Channel; Europe; Great Britain; North Atlantic; United Kingdom; Western Europe; Carne Formation; Cornubian Peninsula; Lizard Peninsula; Menheniot England; Mylor Formation; Porthleven England; Portscatho Formation; Southwestern England; Western Approaches Basin
Coordinates:N500000 N510000 W0040000 W0053000
Abstract Numbers:00M/2888
Record ID:2000039335
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
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