Radiometric constraints on hydrothermal circulation in cooling granite plutons; the Jales gold-quartz mineralisation, northern Portugal

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Authors:Neiva, A. M. R.; Dodson, M. H.; Rex, D. C.; Guise, P. G.
Author Affiliations:Primary:
University of Coimbra, Coimbra, Portugal
Other:
University of Leeds, United Kingdom
Volume Title:Mineralium Deposita
Source:Mineralium Deposita, 30(6), p.460-468. Publisher: Springer-Verlag, Berlin, Federal Republic of Germany. ISSN: 0026-4598
Publication Date:1995
Note:In English. 23 refs.; illus., incl. 6 tables, geol. sketch map
Summary:In Jales, a Hercynian porphyritic two-mica granite and pre-Ordovician mica schists are cut and intensely altered by the Campo Au-quartz vein. The unaltered granite must be younger than 320 ± 6 m.y., and gives mica Rb-Sr ages of 308.5 ± 2.4 m.y. (muscovite) and 294.5 ± 1.1 m.y. (biotite). Further age data on the rocks are presented, the results suggesting that circulation of the Campo mineralizing fluids occurred not more than 2-4 m.y. after the granite cooled through the muscovite Rb-Sr closure T and that subsequent cooling to biotite closure occurred at <<<[dollar]I> 14°C/m.y. The mean cooling rate following emplacement was 15-25°C/m.y. The most detailed comparable published data for the Cornubian ore field imply much faster cooling rates. [R.E.S.]
Subjects:Ar-40/Ar-39; Argon; Controls; Cooling; Framework silicates; Gold ores; Granitic composition; Hydrothermal conditions; Intrusions; Isotopes; Metal ores; Mineral deposits, genesis; Noble gases; Orogeny; Plutons; Quartz; Radioactive isotopes; Silica minerals; Silicates; Stable isotopes; Time factor; Variscan Orogeny; Europe; Iberian Massif; Iberian Peninsula; Portugal; Southern Europe; Jales Deposit; Northern Portugal
Abstract Numbers:96M/1312
Record ID:1996014577
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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