Sobre la asociación de Enclaves Magmáticos Microgranulares (EMM) y monzogranitos con cordierita del plutón de Sierra Bermeja (SO España)

Magmatic Microgranular Enclaves (MMEs) included in the cordierite-bearing monzogranites of the Sierra Bermeja Pluton (southern Iberian Massif) have been examined to elucidate their possible petrogenetic linkage. Mineralogical differences such as the absence of Crd and Kfs in the MMEs, or the compositions of Bt and Pl, as well as the lack of correlations of some elements in whole-rock geochemistry, point to a separate origin for the MMEs and host monzogranites. The MMEs could represent minor globules of a more mafic magma injected into and comingled with the host monzogranitic magma, without causing significant modifications in the geochemical characteristics of the latterLos Enclaves Magmáticos Microgranulares (EMM) del plutón de Sierra Bermeja (Macizo Ibérico meridional) han sido estudiados para esclarecer su posible relación petrogenética con los monzogranitos cordieríticos encajantes. Diferencias mineralógicas como la ausencia de Crd y Kfs en los EMM, o las composiciones de Bt y Pl, así como la falta de correlación de algunos elementos en geoquímica de roca total, apuntan a orígenes independientes para los EMM y los monzogranitos encajantes. Los EMM representarían glóbulos de un magma más máfico inyectado y entremezclado con el magma monzogranítico, sin modificar significativamente las características geoquímicas de este últim

The Tres Arroyos Granitic Aplite-Pegmatite Field (Central Iberian Zone, Spain): Petrogenetic Constraints from Evolution of Nb-Ta-Sn Oxides, Whole-Rock Geochemistry and U-Pb Geochronology

Abundant Li-Cs-Ta aplite-pegmatite dykes were emplaced in the western Central Iberian Zone of the Iberian Massif during the Variscan Orogeny. Their origin and petrogenetic relationships with the widespread granitoids have led to a currently rekindled discussion about anatectic vs. granitic origin for the pegmatitic melts. To deal with these issues, the aplite-pegmatite dykes from the Tres Arroyos area, which constitute a zoned pegmatitic field related to the Nisa-Alburquerque granitic batholith, have been studied. This work comprises a complete study of Nb-Ta-Sn oxides’ mineralogy, whole-rock geochemistry, and U-Pb geochronology of the aplite-pegmatites that have been grouped as barren, intermediate, and Li-rich. The most abundant Nb-Ta-Sn oxides from Tres Arroyos correspond to columbite-(Fe), columbite-(Mn) and cassiterite. Niobium-Ta oxides show a marked increase in the Mn/(Mn+Fe) ratio from the barren aplite-pegmatites up to the Li-rich bodies, whereas variations in the Ta/(Ta+Nb) ratio are not continuous. The probable factors controlling fractionation of Mn/Fe and Ta/Nb reflected in Nb-Ta oxides may be attributed to the crystallization of tourmaline, phosphates and micas. The lack of a progressive Ta/Nb increase with the fractionation may be also influenced by the high F and P availability in the parental pegmatitic melts. Most of the primary Nb-Ta oxides would have crystallized by punctual chemical variations in the boundary layer, whereas cassiterite formation would be related to an undercooling of the system. Whole-rock composition of the distinguished lithotypes reflects similar tendencies to those observed in mineral chemistry, supporting a single path of fractional crystallization from the parental Nisa-Alburquerque monzogranite up to the most evolved Li-rich aplite-pegmatites. The age of 305 ± 9 Ma, determined by LA-ICP-MS U-Pb dating of columbite-tantalite oxides, reinforces the linkage of the studied aplite-pegmatites and the cited parental monzogranite.This research was funded by the Spanish Ministry of Economy, Industry and Competitiveness (Project RTI2018-094097-B-100, with ERDF funds), the University of the Basque Country UPV/ EHU (grant GIU18/084) and the European Union’s Horizon 2020 Innovation Programme (grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources). Work of Idoia Garate-Olave has been supported also by the UPV/EHU by means of the “Convocatoria de contratación para la especialización de personal investigador doctor en la UPV/EHU 2019”

Metasomatic effect of Li-bearing aplite-pegmatites on psammitic and pelitic metasediments: Geochemical constraints on critical raw material exploration at the Fregeneda-Almendra Pegmatite Field (Spain and Portugal)

Fluid-assisted mass transfer and re-equilibration of mineral phases are common consequences of metasomatism associated with igneous intrusions. The addition and/or removal of chemical components in these environments may result in the generation of metasomatic aureoles, which can be recognized by their mineralogy and geochemistry. Due to an increasing demand for critical raw materials used in green energy technologies, rare-element granitic pegmatites have seen renewed interest in the mineral exploration industry. Granitic pegma-tites represent potential sources of critical commodities and geochemical studies of their related aureoles help to advance techniques in exploration targeting. Moreover, the role and timing of fluid exsolution during magma-tic-hydrothermal evolution in granitic-pegmatitic systems and concomitant element mobility remain highly debated.We present a prospect-scale systematic study of geochemical haloes generated by LCT (Li-Cs-Ta) family pegmatite dykes from the Fregeneda-Almendra Pegmatite Field, in the Central Iberian Zone of the Iberian Massif (Spain and Portugal). To understand the magnitude of metasomatic processes linked to these intrusions, we performed whole-rock mass-balance calculation of element gains and losses in variably metasomatized psam-mitic and pelitic host metasediments. The results show that F, B, Li, Rb, Cs, Sn, Be, Tl, As, W and S (+/- Mo, Ta) were carried by early exsolved and expelled aqueous fluids. The first evidence of element enrichment is recorded at distances of 4-5 times the thickness of the dykes, with exponentially increasing gains of those fluid-mobile elements proximal to the pegmatite margin. Enrichments that were detected farthest from the pegmatite mar-gins were those of Li and Cs, followed by Rb and, to a lesser extent, Sn, F, B, Be, and Tl. The most evolved (fractionated) aplite-pegmatites generated the broadest haloes, with concentrations higher than 200 ppm Li, 30 ppm Cs, 300 ppm Rb, and 15 ppm Sn in the metasediments indicating proximity to a mineralized dyke. In addition, absolute gains of up to-4000 ppm Li,-1300 ppm Cs,-1300 ppm Rb, and 170 ppm Sn in the host rocks could point to the presence of superimposed haloes from multiple evolved dykes.Financial support was provided by the European Commission's Horizon 2020 Innovation Programme [grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources]; grant RTI2018-094097-B-100 funded by MCIN/AEI/10.13039/501100011033 and, by "ERDF A way of making Europe"; and the University of the Basque Country UPV/EHU [grant GIU18/084]. The authors are grateful to Kathryn M. Goodenough, an anonymous reviewer, and Tania Martins for their constructive comments, which have improved considerably the quality of the manuscript. Editorial handling and helpful suggestions by Franco Pirajno and Allen K. Andersen are also acknowledged. The. Work of I. Garate-Olave has been supported also by the UPV/EHU by means of the "Convocatoria de contratacion para la especializacion de personal investigador doctor en la UPV/EHU 2019". Financial support provided by FCT- Fundacao para a Ciencia e a Tecnologia, I.P., with the ERA-MIN/0001/2017 - LIGHTS project and through the FCT project UIDB/04683/2020 and UIDP/04683/2020 - ICT (Institute of Earth Sciences) is recognized. J. Cardoso - Fernandes has been financially supported within the compass of a Ph.D. Thesis, ref. SFRH/BD/136108/2018, by Portuguese national funds from MCTES through FCT, and co-financed by the European Social Fund (ESF) through POCH - Programa Operacional Capital Humano - and NORTE 2020 regional program

Quartz chemistry of granitic pegmatites: Implications for classification, genesis and exploration

Quartz from 254 pegmatites representing eight pegmatite fields and provinces worldwide was investigated by laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to determine concentrations of trace elements Al, Ti, Li, Ge, B, Be, Rb, Na, K, Ca, P, Ga, Sb, Zn and U. A total of 271 new analyses combined with 535 published LA-ICP-MS quartz chemistry data were evaluated with binary and ternary trace element discrimination plots and principal component analysis (PCA). The classifications applied for discrimination of pegmatite types include the widely applied NYF(Nb-Y-F) - LCT(Li-Cs-Ta) classification and the new RMG (pegmatites derived from residual melts of granite magmatism) - DPA (pegmatites as direct products of anatexis) grouping. Pegmatites of both classifications can be well distinguished via Al-Ti, Al-Li and Al/Ti-Ge/Ti binary trace element plots and the Ti - Al/10 - 10*Ge ternary diagram. PCA applied to Al, Li, Ti, Be, B, Ge and Rb contents in quartz allowed to further distinguish between anatectic DPA-1 (Li-enriched DPA) and granite-pluton-derived RMG-1 (Li-enriched RMG) pegmatites. Some pegmatite fields and provinces (Hagendorf-Pleystein, Oxford County) are distinguishable by region-specific Li, Ge and Al contents. The results imply that the chemistry of pegmatite quartz is mainly controlled by the origin (source rock chemistry) of pegmatite melts and, to a much lesser extent, by the geodynamic setting of the pegmatite fields and provinces. Chemically primitive NYF and DPA-2 type pegmatites contain quartz with the lowest total trace-element contents and lowest internal-pegmatite trace-element variation, making it potentially suitable for high-tech application. Pegmatite quartz containing >30 μgg-1 Li and >100 μgg-1 Al is strongly indicative of economic spodumene/montebrasite mineralization and, thus, serves as a strong Li-mineralization pathfinder mineral. Quartz with >5 μgg-1 B may be a potential indicator for gem-quality tourmaline mineralization.Fil: Müller, Axel. University of Oslo; Noruega. Natural History Museum; Reino UnidoFil: Keyser, William. University of Oslo; NoruegaFil: Simmons, William B.. Maine Mineral And Gem Museum; Estados UnidosFil: Webber, Karen. Maine Mineral And Gem Museum; Estados UnidosFil: Wise, Michael. Smithsonian Institution; Estados UnidosFil: Beurlen, Hartmut. Universidade Federal de Pernambuco; BrasilFil: Garate Olave, Idoia. Universidad del País Vasco; EspañaFil: Roda Robles, Encarnación. Universidad del País Vasco; EspañaFil: Galliski, Miguel Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Compositional Variations in Apatite and Petrogenetic Significance: Examples from Peraluminous Granites and Related Pegmatites and Hydrothermal Veins from the Central Iberian Zone (Spain and Portugal)

Apatite can be used as an archive of processes occurring during the evolution of granitic magmas and as a pegmatite exploration tool. With this aim, a detailed compositional study of apatite was performed on different Variscan granites, pegmatites and quartz veins from the Central Iberian Zone. Manganese in granitic apatite increases with increasing evolution degree. Such Mn increase would not be related to changes in the fO2 during evolution but rather to a higher proportion of Mn in residual melts, joined to an increase in SiO2 content and peraluminosity. In the case of pegmatitic apatite, the fO2 and the polymerization degree of the melts seem not to have influenced the Mn and Fe contents but the higher availability of these transition elements and/or the lack of minerals competing for them. The subrounded Fe-Mn phosphate nodules, where apatite often occurs in P-rich pegmatites and P-rich quartz dykes, probably crystallized from a P-rich melt exsolved from the pegmatitic melt and where Fe, Mn and Cl would partition. The low Mn and Fe contents in the apatite from the quartz veins may be attributed either to the low availability of these elements in the late hydrothermal fluids derived from the granitic and pegmatitic melts, or to a high fO2. The Rare Earth Elements, Sr and Y are the main trace elements of the studied apatites. The REE contents of apatite decrease with the evolution of their hosting rocks. The REE patterns show in general strong tetrad effects that are probably not related to the fluids’ activity in the system. On the contrary, the fluids likely drive the non-CHARAC behavior of apatite from the most evolved granitic and pegmatitic units. Low fO2 conditions seem to be related to strong Eu anomalies observed for most of the apatites associated with different granitic units, barren and P-rich pegmatites. The positive Eu anomalies in some apatites from leucogranites and Li-rich pegmatites could reflect their early character, prior to the crystallization of feldspars. The increase in the Sr content in apatite from Li-rich pegmatites and B-P±F-rich leucogranites could be related to problems in accommodating this element in the albite structure, favoring its incorporation into apatite. The triangular plots ΣREE-Sr-Y and U–Th–Pb of apatites, as well as the Eu anomaly versus the TE1,3 diagram, seem to be potentially good as petrogenetic indicators, mainly for pegmatites and, to a lesser extent, for granites from the CIZFinancial support was provided by the European Commission’s Horizon 2020 Innovation Programme (grant agreement No 869274, project GREENPEG: New Exploration Tools for European Pegmatite Green-Tech Resources); by Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación (Project RTI2018-094097-B-100, with ERDF funds, A way of making Europe); and by the University of the Basque Country UPV/EHU (grant GIU18/084). The work was also supported by Portuguese National Funds through the FCT–Fundação para a Ciência e a Tecnologia, I.P., with projects UIDB/04683/2020 and UIDP/04683/2020-ICT (Institute of Earth Sciences)

Petrography, mineralogy and origin of the rare element granitic aplopegmatites from Tres Arroyos (Badajoz, Spain)

278 p.El sistema granito-aplopegmatitas de Tres Arroyos (Badajoz) se localiza en las proximidades del batolitode Nisa-Alburquerque. Según su mineralogía y sus características petrográficas y geoquímicas, se handescrito cinco facies, dos graníticas (monzogranito y granito marginal) y tres aplopegmatíticas (estériles,intermedias y enriquecidas en Li), todas ellas encajadas en materiales metamórficos. La mineralogía delos cuerpos aplopegmatíticos se hace más compleja al aumentar su distancia al granito, paralelamente alaumento de su contenido en Li, con lepidolita como principal portador de este elemento. Los distintosindicadores geoquímicos de fraccionamiento tanto en minerales (p. ej. K/Rb en micas y feldespato, Al/Tiy Ge/Ti en cuarzo), como en roca total (p. ej. aumento progresivo en Li, Rb, Cs, Ta, F), indican que elgrado de fraccionamiento aumenta desde el monzogranito hasta las aplopegmatitas más alejadas de este,enriquecidas en Li. Los resultados de la modelización geoquímica (cristalización fraccionada tipoRayleigh) también sugieren que el sistema de Tres Arroyos se originó según una única línea dediferenciación, con un 50% de fraccionamiento para la facies granítica marginal y un 99,9% para losdiques más evolucionados, a partir de una composición similar a la del monzogranito de Nisa-Alburquerque. Además, la edad de este granito está en el rango de la calculada para las aplopegmatitas(301±10 ma, por el método U-Th-Pb en columbita). El desarrollo de texturas unidireccionales (cristalesde feldespato ¿en peine¿ y bandeados rítmicos), la falta de zonación interna de los diques y su carácteraplítico, se atribuyen al fuerte subenfriamiento de los fundidos pegmatíticos al entrar en contacto con laroca de caja más fría, y a la posible exsolución de una fase fluida debida a la pérdida de presión sufridapor el fundido al inyectarse en las fracturas abiertas en las que aparecen encajados los diques

Petrography, mineralogy and origin of the rare element granitic aplopegmatites from Tres Arroyos (Badajoz, Spain)

278 p.El sistema granito-aplopegmatitas de Tres Arroyos (Badajoz) se localiza en las proximidades del batolitode Nisa-Alburquerque. Según su mineralogía y sus características petrográficas y geoquímicas, se handescrito cinco facies, dos graníticas (monzogranito y granito marginal) y tres aplopegmatíticas (estériles,intermedias y enriquecidas en Li), todas ellas encajadas en materiales metamórficos. La mineralogía delos cuerpos aplopegmatíticos se hace más compleja al aumentar su distancia al granito, paralelamente alaumento de su contenido en Li, con lepidolita como principal portador de este elemento. Los distintosindicadores geoquímicos de fraccionamiento tanto en minerales (p. ej. K/Rb en micas y feldespato, Al/Tiy Ge/Ti en cuarzo), como en roca total (p. ej. aumento progresivo en Li, Rb, Cs, Ta, F), indican que elgrado de fraccionamiento aumenta desde el monzogranito hasta las aplopegmatitas más alejadas de este,enriquecidas en Li. Los resultados de la modelización geoquímica (cristalización fraccionada tipoRayleigh) también sugieren que el sistema de Tres Arroyos se originó según una única línea dediferenciación, con un 50% de fraccionamiento para la facies granítica marginal y un 99,9% para losdiques más evolucionados, a partir de una composición similar a la del monzogranito de Nisa-Alburquerque. Además, la edad de este granito está en el rango de la calculada para las aplopegmatitas(301±10 ma, por el método U-Th-Pb en columbita). El desarrollo de texturas unidireccionales (cristalesde feldespato ¿en peine¿ y bandeados rítmicos), la falta de zonación interna de los diques y su carácteraplítico, se atribuyen al fuerte subenfriamiento de los fundidos pegmatíticos al entrar en contacto con laroca de caja más fría, y a la posible exsolución de una fase fluida debida a la pérdida de presión sufridapor el fundido al inyectarse en las fracturas abiertas en las que aparecen encajados los diques

The Tres Arroyos Granitic Aplite-Pegmatite Field (Central Iberian Zone, Spain): Petrogenetic Constraints from Evolution of Nb-Ta-Sn Oxides, Whole-Rock Geochemistry and U-Pb Geochronology

Abundant Li-Cs-Ta aplite-pegmatite dykes were emplaced in the western Central Iberian Zone of the Iberian Massif during the Variscan Orogeny. Their origin and petrogenetic relationships with the widespread granitoids have led to a currently rekindled discussion about anatectic vs. granitic origin for the pegmatitic melts. To deal with these issues, the aplite-pegmatite dykes from the Tres Arroyos area, which constitute a zoned pegmatitic field related to the Nisa-Alburquerque granitic batholith, have been studied. This work comprises a complete study of Nb-Ta-Sn oxides’ mineralogy, whole-rock geochemistry, and U-Pb geochronology of the aplite-pegmatites that have been grouped as barren, intermediate, and Li-rich. The most abundant Nb-Ta-Sn oxides from Tres Arroyos correspond to columbite-(Fe), columbite-(Mn) and cassiterite. Niobium-Ta oxides show a marked increase in the Mn/(Mn+Fe) ratio from the barren aplite-pegmatites up to the Li-rich bodies, whereas variations in the Ta/(Ta+Nb) ratio are not continuous. The probable factors controlling fractionation of Mn/Fe and Ta/Nb reflected in Nb-Ta oxides may be attributed to the crystallization of tourmaline, phosphates and micas. The lack of a progressive Ta/Nb increase with the fractionation may be also influenced by the high F and P availability in the parental pegmatitic melts. Most of the primary Nb-Ta oxides would have crystallized by punctual chemical variations in the boundary layer, whereas cassiterite formation would be related to an undercooling of the system. Whole-rock composition of the distinguished lithotypes reflects similar tendencies to those observed in mineral chemistry, supporting a single path of fractional crystallization from the parental Nisa-Alburquerque monzogranite up to the most evolved Li-rich aplite-pegmatites. The age of 305 ± 9 Ma, determined by LA-ICP-MS U-Pb dating of columbite-tantalite oxides, reinforces the linkage of the studied aplite-pegmatites and the cited parental monzogranite