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

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 ∑REE2O3contents 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) hydrothermal uraninite, which yields an age of 295±2Ma, dates a strong alkali mobilization and early tungsten deposition and ii) a later hydrothermal process, 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

Strategic raw materials for the energy and digital transition in Spain

[EN] One of the main concerns of the European Commission is critical raw materials (CRM), necessary for daily life in a wide range of goods and applications. The EU's industry and economy depend on international markets for many important raw materials, which are produced and supplied by third countries. These CRMs are closely linked to clean technologies, technological progress and quality of life. Concern about access to CRMs led the European Commission to draw up a first list of critical raw materials (CRM) in 2011, and to schedule its review and update every three years, the last being in 2020.Peer reviewe

A GIS-supported Multidisciplinary Database for the Management of UNESCO Global Geoparks: the Courel Mountains Geopark (Spain)

[Abstract] The management of a UNESCO Global Geopark (UGGp) requires a vast wealth of miscellaneous scientific knowledge that can be successfully organised using a Geographical Information System (GIS). This paper presents a pragmatic GIS database to assist in the suitable governance of the Courel Mountains UGGp (2017) in Northwest Spain. The database is structured in 66 coverages compiled from public sources and previous works or produced through traditional mapping (combining fieldwork and photointerpretation) and GIS tools. The acquired data was later homogenised and validated by a multidisciplinary team and archived in independent coverages. Forty thematic maps illustrate the broad range of cartographic information included in the GIS database. Among them, 25 basic maps provide an overview of the UGGp and 15 new maps focus on crosscutting and technical issues. All maps illustrate the huge potential of GIS to create new resources combining coverages and adapting the legend according to their purpose and audience. The database facilitates the suitable publishing of consistent outputs (e.g., brochures, books, panels, webpages, web serves), as well as the elaboration of technical data to assist the park management. The database furnishes information on the design of education actions, touristic routes, activities and Geopark facilities. The GIS database is also a supportive tool for scientific research and provides the necessary knowledge to conduct geoconservation actions based on land use, geological hazards and the occurrence of natural and cultural heritages. Altogether, the GIS database constitutes a powerful instrument for policy-making, facilitating the identification and evaluation of alternative strategy plans.This work was developed in the framework of the Scientific Program of the Courel Mountains UGGp with the cooperation of tourism agents (A.M. Arza and A. López), roofing slate quarries (Pizarras de Villarbacú, Pizarras de Quiroga) and local people (M. Reinosa, G. Díaz, O. Álvarez). We are deeply grateful to J.R. Martínez Catalán (Universidad de Salamanca), A. Pérez-Alberti and J. Guitián (both from Universidade de Santiago de Compostela), J.R. Gutiérrez-Marco (ICOG, Universidad Complutense de Madrid/CSIC), J. Vegas (IGME-CSIC), L. González-Menéndez (IGME-CSIC), J.M. García Queijeiro (Universidade de Vigo), L. Santos and A. Grandal-D’Anglade (both from Universidade da Coruña) for their assistance supplying information involved in the database. We thank also E. de Boer for proofreading the article. DB is grant holder of Plan Andaluz de Investigación, Desarrollo e Innovación 2021, funded by Junta de Andalucí

The Courel Mountains UNESCO Global Geopark: An Amazing Geological History Extended Along 600 Million Years

[EN] The Courel Mountains UNESCO Global Geopark (2019) stands out in SW of Europe because of its geoheritage, its biodiversity and its cultural heritage, all of it considered of international interest. These aspects shape the local development economic and cultural improvement and development. The geoheritage is the result of three geological cycles since the Proterozoic, involving the Cadomian-Avalonian-Pan-African orogeny, the opening of the Rheic Ocean and the Variscan orogeny, and finally the Permian-Mesozoic continental expansion and the Alpine orogeny. The geological history of Courel Mountains is one of singular rocks, huge recumbent folds, valuable metallic mineralization, and invertebrate fossils preserved within metamorphic rocks. This long history is recorded in an exceptional Variscan basement that we can ravel thanks to the exhumation during the Alpine uplifting, when the present-day Courel Mountains were built.Peer reviewe

The Importance of Spanish Data (BDMIN & PANORAMA MINERO) in the European Raw Materials Knowledge Base (EURMKB)

[EN] The IGME has an extensive experience in the field of mineral resources and the main source of information is the Mineral Resources Database (BDMIN) that integrates the geological‐mining information on occurrences, mines and exploitations (active and inactive) of metallic, nonmetallic and industrial minerals, and rocks in Spain. In addition, since 1981, the Panorama Minero has been carried out with the aim of providing reliable data on Spanish mining production, based on the Spanish Mining Statistics (MITERD). This information includes data on the national production of minerals, in tonnage and value, metallurgical production, foreign trade, etc. Other sources include the National Mining Cadastre and Foreign Trade statistics from the Tax Agency.Peer reviewe

Design of a GIS-database for the management of the Courel Mountains UNESCO Global Geopark (Spain)

X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - GasteizSe ha desarrollado una base de datos en un sistema de información geográfica (SIG) para la gestión del Geoparque Mundial de la UNESCO Montañas do Courel (NO de España). El SIG incluye 66 capas de información topográfica, geológica, minera, biológica, arqueológica y etnográfica, que pueden ser combinadas entre sí para elaborar mapas temáticos adaptados a la finalidad y al usuario. Los mapas generados son empleados en actividades de divulgación, en el diseño de cartografías técnicas de apoyo a los gestores del Geoparque, en el desarrollo de estudios científicos y en acciones de geoconservació

Las fuentes primarias de arsénico y otros elementos traza en las aguas subterráneas del sur de la Cuenca del Duero

Jornada de Geología Médica en España (1ª. 2016. Salamanca). - Texto en español, con resumen y palabras claves en español e inglésEn algunos manantiales y sondeos del sur de la Cuenca del Duero (CD) se han detectado niveles de arsénico, y de otros elementos traza (Cr y V), que exceden los límites de potabilidad del agua. El origen de estos elementos en las aguas subterráneas es geogénico y está presente en las rocas sedimentarias de la cuenca, pero las fuentes primarias no se conocen. Con el fin de saber si las mineralizaciones hidrotermales y el conjunto ígneometamórfico pueden ser áreas fuente de estos elementos, se ha llevado a cabo un estudio químico-mineralógico de las fases minerales que los constituyen. Las mineralizaciones de WAs y Sb-As-Au presentes en filones de cuarzo con direcciones NE-SO muestran los contenidos en As más altos. Los análisis de microsonda revelan que los silicatos ferromagnesianos que constituyen el Dique de Messejana-Plasencia (DMP) presentan As, Cr y V en su composición, siendo las enstatitas-ferrosilitas las que muestran mayor contenido en As, con valores máximos del 0,6 % en peso en As2O3. Los sulfuros de las venas de cuarzo mineralizadas y los piroxenos del DMP pueden ser considerados fuentes primarias potenciales de los contenidos elevados en As, Cr y V de las aguas subterráneas de la CD. = High levels of arsenic, and other trace elements (Cr and V), which are above the drinking-water limits, have been observed in springs and boreholes of the Duero Basin (DB). The source of these elements in groundwater is geogenic and it is present in the sedimentary rocks of the basin, but the primary sources remain unknown. In order to know if the hydrothermal mineralization and the igneous-metamorphic rocks could be some of the multiples sources of these elements, a mineralogical-chemical study of their mineral phases was realized. The highest As content has been detected in the W-As and Sb-As-Au-bearing quartz veins deposits with NE-SO regional structural trend. Microprobe analyses reveal that ferromagnesian silicates from the Messejana-Plasencia dyke (MPD) contain As, Cr and V. Highest As content has been found in Mg-Fe pyroxene of the enstatite-ferrosilite series, with values up to 0.6 wt. % As2O3. The sulfide mineralization in quartz veins and the pyroxenes from the MPD can be considered as some of the potential primary sources of the elevated As, Cr and V in groundwater of the DB.Unidad de Salamanca, Departamento de Investigación en Recursos Geológicos, Instituto Geológico y Minero de España, Españ

Isótopos Estables (O, H) en los Depósitos de Wolframio de Los Santos-El Cabaco (Salamanca)

Reunión Científica de la Sociedad Española de Mineralogía (36ª. 2017. Oviedo)Algunas de las mineralizaciones hidrotermales de wolframio más importantes de la Península Ibérica, están asociadas a las rocas graníticas peralumínicas de edad varisca de la Zona Centro Ibérica. Concretamente, las que se encuentran en el Sistema Central, en el Dominio del Complejo Esquisto Grauváquico (CEG). El skarn de scheelita de Los Santos y las venas de cuarzo con sulfuros, scheelita y oro de El Cabaco, ambos en el sur de Salamanca (España), constituyen un buen ejemplo de ello. A pesar de la importancia económica de este tipo de mineralizaciones, hay pocos estudios orientados a la caracterización de la actividad hidrotermal en este sector del Sistema Central. En este trabajo, se discuten los datos de isótopos estables junto con los petrológicos, mineralógicos, químicos y de inclusiones fluidas de estas mineralizaciones, con el objetivo de conocer si forman parte del mismo sistema hidrotermal enriquecido en W.Unidad de Salamanca, Instituto Geológico y Minero de España, EspañaDepartamento de Geología, Universidad de Salamanca, Españ

Caracterización mineralógica y textural de las mineralizaciones de Cu-Au de las áreas de Cuevas del Sil y Andarraso (León, España)

Comunicaciones del Congreso SEM 2023, XL Reunión Científica de la Sociedad Española de Mineralogía; Madrid, 16 de junio de 2023.[ES] Las mineralizaciones de Cu-Au estudiadas están encuadradas en las áreas de Cuevas del Sil y Andarraso, en las minas de Peña Negra y Santibáñez de la Lomba, respectivamente, en el NO de la provincia de León (Fig. 1A). La primera fue explotada hasta 1958 para la obtención de Cu y Au y la segunda hasta los años 20 para el Cu, el Pb y el Au. Han sido objeto de exploración para el Au por la Junta de Castilla y León en 1986 y por SIEMCALSA en 1997, realizándose una investigación posterior, en el año 2002, en el marco del Proyecto de Investigación FEDER. En este trabajo se describen las características morfológicas, mineralógicas, texturales y geoquímicas de estas mineralizaciones, con el objeto de determinar la secuencia paragenética y la distribución del oro.Peer reviewe

Enriquecimiento de arsénico en niveles limosos de la Cuenca del Duero

Jornada de Geología Médica en España (1ª. 2016. Salamanca). - Texto en español, con resumen y palabras claves en español e inglésEl estudio mineralógico y geoquímico de once muestras tomadas en diferentes niveles de un sondeo, de 500 m de profundidad, en sedimentos neógenos del sector sur de la Cuenca del Duero, ha permitido establecer que dichos sedimentos están constituidos fundamentalmente por porcentajes variables de cuarzo, feldespato potásico, plagioclasa y filosilicatos (illita, caolinita y esmectita). Los niveles más limosos y/o arcillosos y con mayores porcentajes en filosilicatos presentan contenidos en As más elevados, siendo estos contenidos localmente anómalos en los niveles más limosos. El As se encuentra asociado a diferentes minerales: filosilicatos, óxidos de Fe y/o Ti y de Mn y, de forma ocasional, sulfuros. = mineralogical and geochemical research work was carried out on eleven samples collected from a borehole 500 m deep performed in the neogene sediments of the southern sector of the Duero Basin. This study has allowed to establish these sediments contain variable amounts of quartz, K-feldspar, plagioclase and phyllosilicates (illite, kaolinite and smectite). Silt- and/or clay-rich beds, with higher percentages of phyllosilicates, show the highest levels of As. These silty beds locally contain anomalous concentrations of As. As is mainly associated with phyllosilicates, Fe and/or Ti and Mn oxides, and sometimes with sulphides.Departamento de Geología, Universidad de Salamanca, EspañaUnidad de Salamanca, Departamento de Investigación en Recursos Geológicos, Instituto Geológico y Minero de España, Españ