Person: Villaseca González, Carlos
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First Name
Carlos
Last Name
Villaseca González
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Petrología y Geoquímica
Identifiers
112 results
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Now showing 1 - 10 of 112
Publication Mineral chemistry of late Variscan gabbros from central Spain: constraints on crystallisation processes and nature of the parental magmas(Universidad Complutense de Madrid, 2015) Orejana García, David; Losantos, E.; Villaseca González, Carlos; Jeffries, T.E.Major and trace element chemistry has been determined in the main minerals (olivine, orthopyroxene, clinopyroxene, plagioclase, amphibole, phlogopite) from the Talavera and La Solanilla gabbroic intrusions (Spanish Central System). The results show a heterogeneous mineral composition illustrative of the chemical evolution of calc-alkaline basic magmas during crystallization. The formation of incompatible element-rich interstitial minerals, such as amphibole, phlogopite and accessory phases (e.g., zircon, apatite), and the presence of zoning patterns in major minerals towards a more evolved composition, point to a progressive differentiation of the parental melt. The chemical variation depicted by trace elements usually incompatible with clinopyroxene (e.g., rare earth elements (REE), Th, Zr, Nb, Ti) implies co-precipitation with phases displaying a compatible behaviour with respect to these elements (e.g., apatite, zircon, amphibole). However, the very high LILE (large ion lithophile elements) and LREE (light REE) shown by clinopyroxene can not be explained exclusively by a closed-system in-situ crystallization process. Several features of the mineral chemistry (e.g. positive correlation of (La/Sm)N with La and Na in clinopyroxene and plagioclase, respectively) support the involvement of an external component (wall-rock assimilation or hybridization with an evolved melt). The petrography and mineral chemistry of the gabbros, in conjunction with bulk rock data from previous studies, favour a calc-alkaline affinity for the parental melts. Thus, metasomatism in the mantle sources related with this basic magmatism might be associated with recycling of crustal components during the Variscan orogeny.Publication Early Proterozoic zircons in Variscan gabbros from central Spain: Evidence of an Icartian magmatic event at mantle depths?(Elsevier Science Ltd, 2009) Villaseca González, Carlos; Orejana García, David; Armstrong, R.A.; Pérez-Soba Aguilar, Cecilia; Merino Martínez, EnriquePublication Caracterización mineral del granito peralumínico de Logrosán (Cáceres, España)(Sociedad Geológica de España, 2011) Chicharro Álvarez, Eva; Villaseca González, Carlos; López García, José Ángel; Oyarzun, RobertoEl granito de Logrosán (Cáceres, España) comprende un complejo stockwork intragranítico de venas de Sn-W y venas de fosfato periféricas encajadas en el Complejo Esquisto Grauváquico (CEG). El emplazamiento del granito de Logrosán tuvo lugar probablemente durante la tercera fase de la Orogenia Varisca. La intrusión del mismo provocó una extensa aureola de metamorfismo que afecta al CEG. El stock de Logrosán se clasifica como un leucogranito peralumínico, rico en fósforo y en flúor con diques de aplita y pegmatitas turmaliníferas. El proceso de fracturación y circulación de los fluidos mineralizados indujo una alteración tipo greisen en el encajante granítico. Los minerales principales son el cuarzo, el feldespato potásico, la plagioclasa, la moscovita, la biotita y el apatito. Se han analizado muestras del granito y del greisen mediante microsonda electrónica con el fin de caracterizar la naturaleza química de la mineralogía principal. [ABSTRACT] The Logrosán granite (Cáceres, SW Spain), shows a complex intragranitic stockwork of Sn-W veins and peripheral phosphate veins hosted by Precambrian slates. The Logrosán pluton emplacement probably took place during the third phase of the Variscan Orogeny. The granite intrusion created an extensive metamorphic aureole which affects the Precambrian slates. The Logrosán stock is classified as a peraluminous, P-rich and F-rich leucogranite, with aplite dikes and tourmaline bearing pegmatites. A greisen alteration was induced during tin-veining in the host granitic rock. The main rock-forming minerals include quartz, K-feldspar, plagioclase, muscovite, biotite and apatite. Samples of granite and greisen veins were analysed and examined by electron microprobe to characterize the chemical nature of the main mineralogy.Publication Mineral chemistry of megacrysts and associated clinopyroxenite enclaves in the Calatrava volcanic field: crystallization processes in mantle magma chambers(Universidad Complutense de Madrid, 2019) Villaseca González, Carlos; Dorado, Olaya; Orejana García, DavidMegacristales de clinopiroxeno, anfíbol y flogopita aparecen en los depósitos piroclásticos ricos en cristales, enclaves y xenolitos, de los volcanes de El Aprisco y Cerro Pelado (campo volcánico de Calatrava). Estos megacristales muestran una composición química similar a los cristales que forman los enclaves clinopiroxeníticos asociados, incluyendo los poco comunes enclaves ricos en flogopita (glimmeritas). El magma volcánico es de textura porfídica, mostrando una compleja población de fenocristales y macrocristales máficos, con núcleos residuales, que sugieren formen una suite cogenética con aquellos. Las estimaciones geobarométricas indican que los megacristales, así como los núcleos de fenocristales y los enclaves clinopiroxeníticos representan acumulados de alta presión, formados entre 12–16 kbar, en el manto litosférico superior (de 35 a 55 km). La variabilidad composicional de estos minerales máficos apunta a un proceso de diferenciación controlado por la cristalización de olivino, clinopiroxeno, anfíbol y flogopita. La cristalización de minerales máficos hidratados en el manto facilitaría la exsolución de CO2 y la subsecuente ebullición del fundido, posibilitando la fragmentación de los márgenes semicristalinos de la cámara magmática y la excavación de la roca mantélica encajante. Esta fragmentación profunda explicaría también la compleja variedad de cristales, enclaves y xenolitos atrapados por los magmas volcánicos. Se han encontrado dos tipos de clinopiroxenos (verde e incoloro) que aparecen como antecristales (núcleos de macrocristales/fenocristales) y también en los enclaves piroxeníticos. La coexistencia de ambos tipos de clinopiroxeno en los zonados cristalinos de las clinopyroxenitas sugiere que deben ser cogenéticos, representando precipitados de fundidos de distinto grado evolutivo, pero posiblemente de un mismo magma fraccionante. Este estudio propone un modelo de ascenso y origen de magmas ricos en cristales y xenolitos que puede ser útil para explicar otros tipos volcánicos que transportan complejos cargamentos de cristales profundos, como ocurre frecuentemente en la provincia volcánica circum-Mediterránea.Publication Geochemistry and geochronology of mafic rocks from the Spanish Central System: Constraints on the mantle evolution beneath central Spain(Elsevier, 2019) Orejana García, David; Villaseca González, Carlos; Kristoffersen, M.The Spanish Central System (SCS) contains several suites of Palaeozoic mafic igneous intrusions with contrasting geochemical affinity: Ordovician tholeiitic metabasites, Variscan calc-alkaline gabbros (Gb1) and microdiorites (Gb2), shoshonitic monzogabbros (Gb3) and alkaline diabases and lamprophyres (Gb4). Not all of these rocks are accurately dated, and several aspects of their genesis are still poorly understood. We present new whole-rock geochemical data (major and trace elements, and Sr–Nd isotopes), U–Pb and Lu–Hf isotopic ratios on magmatic zircons and 40Ar/39Ar amphibole geochronology results in order to establish a precise chronology for the successive events of magmatism in the SCS, and discuss the nature of their mantle sources. Accurate ages have been determined for the Variscan gabbros (305–294 Ma), the microdiorites (299 Ma) and the accompanying felsic porphyries (292 Ma), the shoshonitic monzogabbros (285 Ma), and the alkaline diabases (274 Ma) and monzosyenites (271–264 Ma). According to this information, the Variscan mafic magmatism would be mainly concentrated in the range of 305–294 Ma, with a final manifestation represented by the minor shoshonitic dykes. The alkaline magmatism proved to be slightly older than previously thought and yielded at least two distinct pulses: diabases and lamprophyres–monzosyenites. Zircon Hf isotopes evidence the involvement of depleted and slightly enriched mantle sources. The bulk of the εHf values are in the broad range of −8 to +11, indicative of melting both depleted and enriched mantle regions. The high within-sample Hf isotope variation (up to ~11 epsilon units) shown by samples from the Variscan series (gabbros, microdiorites and monzogabbros) could be explained mainly by hybridisation of magmas derived from heterogeneous lithospheric mantle sources. Pressure estimates indicate that the Variscan mafic magmas were extracted from the lithosphere. The Nd–Hf isotopic composition of these suites of rocks suggests the recycling of pelitic sediments during the Cadomian orogeny. Deeper (asthenospheric) mantle levels were involved in the generation of the alkaline suite, whose anomalous negative εHf values (moderately decoupled with respect to radiogenic Nd) could be associated with subducted oceanic components raised by mantle upwelling associated with lithosphere thinning and extension during the Permian.Publication Petrogenesis of highly fractionated I-type peraluminous granites: La Pedriza pluton (Spanish Central System)(Instituto de Ciencias de la Tierra "Jaume Almera" (Barcelona), 2010) Pérez-Soba Aguilar, Cecilia; Villaseca González, CarlosThe La Pedriza pluton stands out as the most extensively fractionated granite (Rb < 629; Sr < 2 and Ba < 2 ppm) of the Spanish Central System Batholith. These granites show a strong enrichment in some rare metal contents (Nb = 44, Y = 136, Yb = 10.7, U = 17, Ta = 7, Sc = 15 ppm). The petrography and geochemistry (including Sr- Nd isotopes) reveal that the pluton is composed of at least four units. These are classified as I-type peraluminous leucogranites (A/CNK=1.03-1.17), P-poor (P2O5<0.2 wt%) and Na2O-rich (< 4.24 wt%) exhibiting differences in their HFSE and REE contents and εNd compositions. Moreover, the units of the La Pedriza granite display different trends of fractional crystallization. REE spectra of the two most fractionated units suggest the involvement of a fluorine-rich melt in the last stages favouring the crystallization of xenotime and niobotantalates. Intermediate meta-igneous granulite protoliths are proposed as source rocks. The most evolved units of the La Pedriza pluton show chemical features convergent to A-type granites; these are explained by extensive fractional crystallization of a P-poor, I-type granite magma.Publication Aplicaciones geotermobarométricas de los contenidos en elementos trazas de minerales granulíticos: Zr en rutilo y HREE en granate de los xenolitos félsicos de la corteza inferior del Sistema Central Español(Sociedad Geológica de España, 2006) Villaseca González, Carlos; Orejana García, DavidGeothermobarometric estimations based on the trace element concentration of minerals from lower crustal peraluminous felsic granulite xenoliths from the Spanish Central System (SCS) have been performed. Zr in rutile thermometry (Zack et al., 2004) gives a main range of 970 to 1100 ºC whereas HREE in garnet barometry (Bea et al., 1997) yields a pressure range of 7.2 to 9.3 kbar. These new thermobarometric data overlap previous P-T estimates based on conventional metamorphic phase equilibria. Nevertheless, the slightly higher temperature range obtained with rutile thermometry force to future revision of granulite mineral equilibria of the SCS lower crustal xenoliths.Publication Origin, ore forming fluid evolution and timing of the Logrosán Sn–(W) ore deposits (Central Iberian Zone, Spain)(Elsevier, 2016-01) Chicharro, Eva; Boiron, Marie-Christine; López-García, José Ángel; Barfod, Dan N.; Villaseca González, CarlosThe Logrosán Sn–(W) ore deposits in the metallogenic Sn–W province of the European Variscan Belt consist of endoand exogranitic greisen-type and quartz–cassiterite veins associated with a S-type granite. Mineral characterization, fluid inclusion study, isotope geochemistry and Ar–Ar geochronology have been combined in order to reconstruct the conditions for Sn–(W) mineralization. The endo- and exogranitic mineralization must have been developed in a relatively long-lived system (~308–303 Ma), during or soon after the emplacement of the Logrosán relatedgranite (at ca. 308 Ma). The mineralizing fluids are characterized by complex aqueous and volatile (H2O–N2–CO2– CH4–NaCl) fluid inclusions. Microthermometry and Raman analyses indicate that fluid composition evolved from N2–CH4 to N2-rich, followed by CO2-rich fluids, with varying amounts of H2O. The presence of N2 and CH4 suggests the interaction with fluids derived from the nearby metasedimentary host rocks. A model of host-rock interaction, assimilation, and mixing of metamorphic and magmatic fluids, resulting in change of the redox conditions, is proposed for tin deposition. Later sulfide minerals were precipitated as a result of pressure and temperature releasePublication Estimación del régimen térmico y producción de calor de los niveles litosféricos del Sistema Central Español(Sociedad Geológica de España, 2005) Villaseca González, Carlos; Orejana García, David; Pérez-Soba Aguilar, Cecilia; Reyes Andrés, JesúsHeat production of outcropping metamorphic and granitic rocks from the Spanish Central System (SCS) is similar to other surface heat production estimates in Paleozoic provinces (average A value 2.64 mWm-3). However, heat flow range in the SCS is higher than for Paleozoic terranes (70-90 mWm-2 instead of 45-70 mWm-2). Contribution of mantle to the heat budget is estimated to be 27 mWm-2. Thus, a slightly higher mantle heat flow combined with a lower crust with a markedly high heat production (average A value 1.04 mWm-3) may explain the high estimated surface heat flow.Publication Petrografía de rocas ígneas(2008-10-02) Villaseca González, Carlos; Andonaegui Moreno, Pilar; Huertas Coronel, María José; Orejana García, DavidEs un tratado práctico de petrografía de rocas ígneas o magmáticas que cubre diversos aspectos: mineralogía fundamental y accesoria de las rocas magmáticas; fábrica (textura y estructura) de las rocas ígneas; clasificaciones modales y descripción de los principales tipos de rocas y series ígenas, tanto volcánicas como plutónicas.