The nodular granite of Castanheira, north central Portugal; origin of the nodules and evidence for diapiric mobilization of granite

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Authors:Reavy, R. J.; Hutton, D. H. W.; Finch, A. A.
Author Affiliations:Primary:
University of Oxford, Department of Earth Sciences, Oxford, United Kingdom
Other:
University of Durham, United Kingdom
University of Aberdeen, United Kingdom
Volume Title:Geological Magazine
Source:Geological Magazine, 130(2), p.145-153. Publisher: Cambridge University Press, London, United Kingdom. ISSN: 0016-7568
Publication Date:1993
Note:In English. 9 refs.; illus. incl. 2 tables, sect., geol. sketch maps
Summary:The pluton is a small (1000 x 600 m) body which contains a remarkable abundance of granite-cored, biotite-rimmed nodules. These are interpreted as representing original bubbles in the uppermost volatile-rich zone of a granitic plutonic. Strong depletion in Rb and K in the host granite around the nodules suggests that the biotite is magmatic in origin. The nodules may have formed by reaction between chloroferrate (II) complexes in the vapour phase and silicate melt, possibly following condensation of the vapour phase to a small granitic core. Motion of the vapour bubble stabilized a gradient in chemical potential with respect to the host granite,giving rise to the nodules. Chemical, petrological and structural data suggest that the pluton was part of a larger body which was forcefully emplaced during synchronous transcurrent shearing. [C.H.D.]
Subjects:Diapirs; Emplacement; Genesis; Granites; Igneous rocks; Inclusions; Intrusions; Plutonic rocks; Plutons; Shear; Xenoliths; Europe; Iberian Peninsula; Portugal; Southern Europe; Castanheira Pluton; North-central Portugal
Abstract Numbers:93M/4777
Record ID:1993019894
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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040 |a ViAlAGI  |c ViAlAGI 
072 7 |a 05A  |2 georeft 
100 1 |a Reavy, R. J.  |e analytic author  |u University of Oxford, Department of Earth Sciences, Oxford 
245 1 4 |a The nodular granite of Castanheira, north central Portugal; origin of the nodules and evidence for diapiric mobilization of granite 
300 |a p. 145-153 
500 |a In English. 9 refs. 
500 |a Abstract number: 93M/4777 
500 |a Abstractor: C.H.D. 
500 |a Affiliation: University of Oxford, Department of Earth Sciences; Oxford; GBR; United Kingdom 
500 |a Affiliation: University of Durham; ; GBR; United Kingdom 
500 |a Affiliation: University of Aberdeen; ; GBR; United Kingdom 
500 |a Key title: Geological Magazine 
500 |a Source note: Geological Magazine, 130(2), p.145-153. Publisher: Cambridge University Press, London, United Kingdom. ISSN: 0016-7568 
500 |a Publication type: journal article 
504 |b 9 refs. 
510 3 |a GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom 
520 |a The pluton is a small (1000 x 600 m) body which contains a remarkable abundance of granite-cored, biotite-rimmed nodules. These are interpreted as representing original bubbles in the uppermost volatile-rich zone of a granitic plutonic. Strong depletion in Rb and K in the host granite around the nodules suggests that the biotite is magmatic in origin. The nodules may have formed by reaction between chloroferrate (II) complexes in the vapour phase and silicate melt, possibly following condensation of the vapour phase to a small granitic core. Motion of the vapour bubble stabilized a gradient in chemical potential with respect to the host granite,giving rise to the nodules. Chemical, petrological and structural data suggest that the pluton was part of a larger body which was forcefully emplaced during synchronous transcurrent shearing. 
650 7 |a Diapirs  |2 georeft 
650 7 |a Emplacement  |2 georeft 
650 7 |a Genesis  |2 georeft 
650 7 |a Granites  |2 georeft 
650 7 |a Igneous rocks  |2 georeft 
650 7 |a Inclusions  |2 georeft 
650 7 |a Intrusions  |2 georeft 
650 7 |a Plutonic rocks  |2 georeft 
650 7 |a Plutons  |2 georeft 
650 7 |a Shear  |2 georeft 
650 7 |a Xenoliths  |2 georeft 
651 7 |a Europe  |2 georeft 
651 7 |a Iberian Peninsula  |2 georeft 
651 7 |a Portugal  |2 georeft 
651 7 |a Southern Europe  |2 georeft 
653 |a Castanheira Pluton 
653 |a North-central Portugal 
700 1 |a Hutton, D. H. W.,  |e analytic author  |u University of Durham 
700 1 |a Finch, A. A.,  |e analytic author  |u University of Aberdeen 
773 0 |t Geological Magazine  |d London : Cambridge University Press, Mar. 1993  |x 0016-7568  |y GEMGA4  |n Geological Magazine, 130(2), p.145-153. Publisher: Cambridge University Press, London, United Kingdom. ISSN: 0016-7568 Publication type: journal article  |g Vol. 130, no. 2  |h illus. incl. 2 tables, sect., geol. sketch maps