Fluid evolution related to gold mineralisation in the central Iberian zone
Fluid evolution related to gold mineralisation in the central Iberian zone
The Central Iberian Zone of Spain and Portugal contains numerous gold deposits of varying size, age and host lithology. Previous work has concentrated on single deposits, and as a result there was a need to apply a range of techniques to the region as a whole, in order to form a model for metallogenesis throughout the region. This work forms part of a EC-funded project (Contract MA2M-0032) studying integrated multidisciplinary exploration techniques for gold and precious metals in the Western Iberian peninsula.
The Central Iberian Zone consists essentially of greenschist facies metasedimentary units intruded by Hercynian granitoids. Hercynian deformation occurred in three main stages, of which the earliest (D1) was the most intense. Quartz veining is common throughout the region, and a vein chronology was established relative to these deformation events. V1 veins are pre-Hercynian, and may predate the Precambrian Sardic deformation. V2 veins are syndeformational (D1), and associated with peak greenschist metamorphism. V3 veins are late-kinematic, syn- to post-D2. V4 veins are syn- to post-D3, occurring in the final stages of the Hercynian, and often associated with or postdating granites. Reactivation of vein sets by later fluids was common.
Fluid chemistry studies of samples of known chronology indicate 3 main sources of fluid. The dominant fluid throughout the region from V2 to V4 is a dilute aqueo-carbonic fluid of varying composition. The combination of microthermometry, geochemical studies of wallrock alteration and stable isotope systematics indicates that the fluid was the result of devolatilisation and dehydration during prograde metamorphism at varying depths. The resulting aqueo-carbonic fluids flowed upwards, mixing with each other and with meteroric waters. Contact metamorphism associated with granite intrusions during the D3 deformation released further aqueo-carbonic fluids, which in some cases unmixed to form separate carbonic and aqueous inclusions.
University of Southampton
1994
Murphy, Pamela Jane
(1994)
Fluid evolution related to gold mineralisation in the central Iberian zone.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Central Iberian Zone of Spain and Portugal contains numerous gold deposits of varying size, age and host lithology. Previous work has concentrated on single deposits, and as a result there was a need to apply a range of techniques to the region as a whole, in order to form a model for metallogenesis throughout the region. This work forms part of a EC-funded project (Contract MA2M-0032) studying integrated multidisciplinary exploration techniques for gold and precious metals in the Western Iberian peninsula.
The Central Iberian Zone consists essentially of greenschist facies metasedimentary units intruded by Hercynian granitoids. Hercynian deformation occurred in three main stages, of which the earliest (D1) was the most intense. Quartz veining is common throughout the region, and a vein chronology was established relative to these deformation events. V1 veins are pre-Hercynian, and may predate the Precambrian Sardic deformation. V2 veins are syndeformational (D1), and associated with peak greenschist metamorphism. V3 veins are late-kinematic, syn- to post-D2. V4 veins are syn- to post-D3, occurring in the final stages of the Hercynian, and often associated with or postdating granites. Reactivation of vein sets by later fluids was common.
Fluid chemistry studies of samples of known chronology indicate 3 main sources of fluid. The dominant fluid throughout the region from V2 to V4 is a dilute aqueo-carbonic fluid of varying composition. The combination of microthermometry, geochemical studies of wallrock alteration and stable isotope systematics indicates that the fluid was the result of devolatilisation and dehydration during prograde metamorphism at varying depths. The resulting aqueo-carbonic fluids flowed upwards, mixing with each other and with meteroric waters. Contact metamorphism associated with granite intrusions during the D3 deformation released further aqueo-carbonic fluids, which in some cases unmixed to form separate carbonic and aqueous inclusions.
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Published date: 1994
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Local EPrints ID: 458521
URI: http://eprints.soton.ac.uk/id/eprint/458521
PURE UUID: 6c11c855-2574-48cb-90d7-ba5f80e37312
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Date deposited: 04 Jul 2022 16:50
Last modified: 04 Jul 2022 16:50
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Author:
Pamela Jane Murphy
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