Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith
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| Natura: | Artículo científico |
| Lingua: | en |
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Universitat de Barcelona
2019
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| _version_ | 1876448378755219456 |
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| author | S.M. Timón-Sánchez |
| author_facet | S.M. Timón-Sánchez |
| contents | Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith S.M. Timón-Sánchez F.J. López-Moro R.L. Romer D. Rhede A. Fernández-Fernández C. Moro-Benito Ciencias de la Tierra Uraninite Pb dating Au deposits Variscan belt Spanish Central System Batholith The scheelite skarn from Los Santos and the W-Au veins from El Cabaco district, located in the Spanish Central System Batholith (SCSB), are some of the best-known tungsten ore deposits in Spain. Uraninite is an accessory mineral in both deposits, which underwent several hydrothermal flow events. Chemical and textural characteristics as well as electron microprobe U-Th-Pb uraninite chemical data from the different stages of the skarn and the vein-type mineralizations are presented here. Based on these data the uraninite was able to be classified into two groups. Group I uraninite has an octahedral habit and occurs as inclusions in K-feldspar relicts of the leucogranite related to Los Santos skarn formation. It shows high Th (6.95 to 8.51wt.% ThO2) and high Rare Earth Elements (REEs) contents (0.55 to 1.38wt.% ∑REE2O3). Group II uraninite occurs i) associated to El Cabaco granite, in a greenish selvage-style greisen and its reddish envelope and in the mineralized rimming quartz veins and ii) in Los Santos high temperature endoskarn and anorthite skarn, where it is associated with U-rich mica. This uraninite type has lower Th and ∑REE2O3 contents than Group-I uraninite. The mineral chemistry and the assemblage and textural relationships suggest that Group-I uraninite is magmatic and the attained U-Th-Pb chemical age of 300±4Ma is interpreted as the magmatic age of the skarn-forming aplite granites in the western part of the SCSB. Group-II uraninite includes two events: i) a hydrothermal uraninite, which yields an age of 295±2Ma, dates a strong-alkali mobilization and early tungsten deposition and ii) a later hydrothermal processes, around 287±4Ma, that resulted in sulfides and late scheelite precipitation and widespread silicification. Finally, the gold deposition is younger than this silicification according to textural criteria. Therefore, W-Au deposits in the western part of the SCSB were formed by superposition of several processes that took place some 15Ma after the skarn-forming granite crystallized. Comparable W, W-Au and U deposits in the Variscan orogenic belt show a similar timing of hydrothermal events, suggesting that the hydrothermal history was controlled by large-scale Late-Variscan tectonic processes. Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith 2019 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50558790004 https://www.redalyc.org/journal/505/50558790004/ https://www.redalyc.org/journal/505/50558790004/html/ https://www.redalyc.org/journal/505/50558790004/50558790004.epub https://www.redalyc.org/journal/505/50558790004/movil https://doi.org/10.1344/GeologicaActa2019.17.1 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Vol.17 |
| format | Artículo científico |
| id | redalyc_50558790004 |
| institution | Redalyc |
| language | en |
| publishDate | 2019 |
| publisher | Universitat de Barcelona |
| spellingShingle | Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith S.M. Timón-Sánchez Ciencias de la Tierra Uraninite Pb dating Au deposits Variscan belt Spanish Central System Batholith Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith S.M. Timón-Sánchez F.J. López-Moro R.L. Romer D. Rhede A. Fernández-Fernández C. Moro-Benito Ciencias de la Tierra Uraninite Pb dating Au deposits Variscan belt Spanish Central System Batholith The scheelite skarn from Los Santos and the W-Au veins from El Cabaco district, located in the Spanish Central System Batholith (SCSB), are some of the best-known tungsten ore deposits in Spain. Uraninite is an accessory mineral in both deposits, which underwent several hydrothermal flow events. Chemical and textural characteristics as well as electron microprobe U-Th-Pb uraninite chemical data from the different stages of the skarn and the vein-type mineralizations are presented here. Based on these data the uraninite was able to be classified into two groups. Group I uraninite has an octahedral habit and occurs as inclusions in K-feldspar relicts of the leucogranite related to Los Santos skarn formation. It shows high Th (6.95 to 8.51wt.% ThO2) and high Rare Earth Elements (REEs) contents (0.55 to 1.38wt.% ∑REE2O3). Group II uraninite occurs i) associated to El Cabaco granite, in a greenish selvage-style greisen and its reddish envelope and in the mineralized rimming quartz veins and ii) in Los Santos high temperature endoskarn and anorthite skarn, where it is associated with U-rich mica. This uraninite type has lower Th and ∑REE2O3 contents than Group-I uraninite. The mineral chemistry and the assemblage and textural relationships suggest that Group-I uraninite is magmatic and the attained U-Th-Pb chemical age of 300±4Ma is interpreted as the magmatic age of the skarn-forming aplite granites in the western part of the SCSB. Group-II uraninite includes two events: i) a hydrothermal uraninite, which yields an age of 295±2Ma, dates a strong-alkali mobilization and early tungsten deposition and ii) a later hydrothermal processes, around 287±4Ma, that resulted in sulfides and late scheelite precipitation and widespread silicification. Finally, the gold deposition is younger than this silicification according to textural criteria. Therefore, W-Au deposits in the western part of the SCSB were formed by superposition of several processes that took place some 15Ma after the skarn-forming granite crystallized. Comparable W, W-Au and U deposits in the Variscan orogenic belt show a similar timing of hydrothermal events, suggesting that the hydrothermal history was controlled by large-scale Late-Variscan tectonic processes. Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith 2019 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50558790004 https://www.redalyc.org/journal/505/50558790004/ https://www.redalyc.org/journal/505/50558790004/html/ https://www.redalyc.org/journal/505/50558790004/50558790004.epub https://www.redalyc.org/journal/505/50558790004/movil https://doi.org/10.1344/GeologicaActa2019.17.1 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Vol.17 |
| title | Late-Variscan multistage hydrothermal processes unveiled by chemical ages coupled with compositional and textural uraninite variations in W-Au deposits in the western Spanish Central System Batholith |
| topic | Ciencias de la Tierra Uraninite Pb dating Au deposits Variscan belt Spanish Central System Batholith |
| url | https://www.redalyc.org/articulo.oa?id=50558790004 https://www.redalyc.org/journal/505/50558790004/ https://www.redalyc.org/journal/505/50558790004/html/ https://www.redalyc.org/journal/505/50558790004/50558790004.epub https://www.redalyc.org/journal/505/50558790004/movil https://doi.org/10.1344/GeologicaActa2019.17.1 |