Petrología y geoquímica de las rocas filonianas de la región Muxia-Finisterre (Galicia, NW España)

Se estudian las rocas filonianas post-tectónicas de la región Muxia-Finisterre. El conjunto de filones se dispone en dos estructuras anulares sub-concéntricas. Su emplazamiento se relaciona con la intrusión de los granitoides de la serie de las "granodioritas tardías". La estructura zonada de los filones y los datos de composición química sugieren el relleno de las fracturas anulares por dos magmas diferentes, el primero similar al magmacalco-alcalino que genera las "granodioritas tardías" y el segundo, más básico, probablemente relacionado con magmas más profundos precursores básicos de composición "gabro-diorítica" encontrados en las mismas

Cambios metasomáticos y evolución metamórfica de las anfibolitas de Finisterre (NW España)

Las anfibolitas de la región de Finisterre (NW España) pueden ser: i) con piroxeno, ii) con granate - piroxeno, iii) con biotita, iv) con anfíbol solamente. Los análisis químicos de roca total sugieren un origen orto-derivado para algunas de estas rocas. En el contacto con los granitos anatécticos las anfibolitas con piroxeno muestran una serie de cambios mineralógicos y texturales que indican la existencia de un metasomatismo a pequeña escala con aporte de K y H20 desde los granitos a las anfibolitas. La presencia de minerales relictos, piroxenos o anfíboles pardos, e. g., sugiere varios episodios de recristaluación. La evolución de la composición química de los anfíboles indica una recristalización inicial en condiciones de la facies de las granulitas o de las anfibolitas de alto grado y por último en condiciones de la facies de las anfibolitas con epidota o incluso de los esquistos verdes. La correlación de estos episodios de recristalización con la evolución metamórfica de las metapelitas y ortopeises de la misma zona presenta diversos problemas ya que en las anfibolitas no se observa un cambio en el gradiente de P-T con el tiempo tal coino se observa en las demás rocas. Se consideran dos hipótesis: a) las paragénesis con hornblenda ferroan-pargasítica son parigdnesis relictas del primer episodio metamórfico, M 1, b)  corresponden al climax metamórfico que tiene lugar durante M2. I:n cualquier caso sólo es observable una evolución metamórfica continua retrógada en condiciones aparentemente de un metamodismo de P intermedia

Ordovician and Silurian igneous rocks and orthogeneisses in the Catalonian Coastel Ranges

These rocks exhibit calc-alkaline affinities and may have originated by partial melting of the crust in a post-collision, anorogenic setting. Orthogneisses derived from biotite-bearing leucogranites occur within aprobably cambrian heterogeneous series. Petrological and geochemical features suggest that they might be genetically related to the ordovician vulcanites. Basic sills and volcanoclastic rocks occur intercalated within a mainly pelitic formation in the lower part of the Silurian sequence. The silurian igneous rocks are alkali basalts and may reflect an extensional regime

Polyphase tectonic reworking of serpentinites and chlorite-tremolite-talc rocks (SW Spain) from the subduction forearc to intracontinental emplacement

The petrostructural and geochronological study of a poorly known ultramafic unit from SW Spain (Badajoz–Córdoba belt) combined with previous structural data permits disclosure of a history of metasomatism, tectono-metamorphism, reworking and isotopic resetting related to a poly-orogenic evolution in different geodynamic scenarios. The heterogeneous ultramafic unit studied contains antigorite-serpentinites and metasomatized ultramafic rocks (chlorite-talc schists, tremolite-talc-chlorite rocks and magnesio-hornblende-chlorite rocks). Mantle-wedge serpentinization was followed by Si and Al pre- to syn-metamorphic/tectonic metasomatism in a subduction realm. Petrofabrics of selected lithologies reveal variable syn-metamorphic crystal-plastic deformation and recrystallization (assisted by other mechanisms) under relative high pressure, concomitant with the conditions recorded by neighbouring tectonic units that were later intruded by Ordovician granites. The resultant ensemble was reworked and isotopically reset much later in an intracontinental ductile shear zone. Syn- to late-tectonic apatite from chlorite-talc schists provides an anchored Tera–Wassenburg isochron radiometric age of 342.8 ± 12.2 Ma that provides evidence for the decoupling between isotopic systems and microstructures. The results are discussed from a twofold perspective: with regard to the likely tectonic context of this ophiolite (the current analogue of the Mariana forearc) and with regard to regional geological implications.Spanish Ministry of Economy, Industry and Competitiveness and the Fondo Europeo de Desarrollo Regional (MINECO/FEDER CGL2015-63530-P; UPV/EHU (GIU20/010 and GIU15/05)

IBERLID: A lead isotope database and tool for metal provenance and ore deposits research

[EN] Although sometimes controversial, the use of Pb isotope data in geological research of ore deposits and metal provenance studies in archaeology has proved a useful tool for investigation of the relations between ore sources and raw materials used by humans. Users of this kind of information have often asked for complete datasets that would include not only numerical values of isotope ratios but also mineralogical and geological information about the samples analysed so as to allow for conscientious data comparison. The IBERLID database here presented has been designed to include available information for nearly 3000 samples from the Iberian Peninsula and Balearic Islands in a unique, complete to the extent possible, upgradable dataset using standardized variables. This allows to compare data and establish groups based upon isotopic ratios, mineralogy and other geological characteristics of the samples. The database is available through an online interactive public tool (www.ehu.eus/ibercron/iberlid) that provides for data search, comparison and graphics design, and may be furthermore exported for enhanced statistical treatment. By direct use of the proposed standardized variables, the compiled results allow to discern among 3 main mineralization events within the Iberian realm, while interpolation of Pb isotope data allow to draw the first maps of model age, mu and kappa parameters. The problem of radiogenic lead in some compiled data requires additional analyses of elemental concentrations, which so far has been generally neglected.Financial support was provided by the Spanish Ministry of Economy, Industry and Competitiveness, and the European Regional Development Fund (MINECO/ERDF CGL2015-63530-P) , and by the UPV/EHU (GIU15/05) . The authors are grateful to Sabine Klein and two anony-mous reviewers for constructive comments which improved this manuscript, and to Huayong Chen for suggestions and editorial handling

Metamorphism and geothermobarometry of the Yunquera Unit in Casarabonela (Alpujárride Complex, Málaga)

The rocks of the Yunquera Unit (Alpujárride Complex) record two stages, at least, of recrystallization at different P-T conditions defined by the mineral associations: a) Grt + Pl + Ms + St + Ky + Qtz, and b) Grt + Pl + Sill + Qtz ± Bt. The metamorphic peak for the first stage has been estimated at ca. 1200-1300 MPa and 560-695 ºC through conventional thermobarometry. The second mineral association was equilibrated at 600 MPa and 700 ºC. These data support the existence of an initial high-pressure metamorphic stage followed by a pressure drop and final cooling during the Alpine exhumation of the Uni

Masa-espektrometria bidezko prozedura analitiko berrien garapena Geokimika Isotopikoan eta haien aplikazioa presio altuko arroka metamorfikoen azterketan

Geokimika Isotopikoak/Geokronologiak azken hamarkadetan izan duen bilakaerak hainbat teknika analitikoren hobekuntza eragin du, gerriko metamorfikoen tektonikaren gaineko informazioan iraultza eraginez. Euskal Herriko Unibertsitatea (UPV/EHU) berariazko tresneria analitikoaren jabe da, munduan gehien erabiltzen di-ren metodo geokronologikoen inplementazioa eta hobekuntza ahalbidetuz. Lan hone-tan, Rb-Sr eta Lu-Hf sistemak MC-ICP-MS bidez analizatzeko metodologia garatu da alde batetik, eta Hf-Hf eta U-Pb sistemak LA-ICP-MS bidez neurtzeko teknikak beste-tik. Teknika horiek Iberiar mendigunearen ipar-mendebaldeko Malpica-Tui eta Cabo Ortegal Konplexu Aloktonoetako presio altuko arroka metamorfikoen dataziorako eta trazaketarako erabili dira.; The development of Isotope Geochemistry/Geochronology has triggered many technical improvements in the past decades and has revolutionised the potential information available on the tectonics of metamorphic belts. The University of the Basque Country (UPV/EHU) has acquired the specific analytical equipment, which has allowed the implementation and improvement of several of the worldwide most used geochronological methods. In the present work, techniques for Rb-Sr and Lu-Hf analy-sis by MC-ICP-MS, and Hf-Hf and U-Pb analysis by LA-ICP-MS have been devel-oped. These techniques have been employed to date and trace the origin of high-pres-sure rocks from the Malpica-Tui and Cabo Ortegal Allochthonous Complexes of the NW Iberian Massif

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 gold of the Carambolo Treasure: New data on its origin by elemental (LA MS) and lead isotope (MC-ICP)

The Carambolo Treasure (Seville, Spain), is a key collection of materials from the 1st Millennium BC Mediterranean. Besides the uniqueness, technical complexity and beauty of this assemblage of gold associated with the mythical name of Tartessos, the treasure has been at the epicentre of debates over the last 50 years regarding the Phoenician presence in the west and the origin of the first great western civilization. However, the absence of a precise archaeological context and systematic analyses aimed at identifying the source of the supply of gold have led to diverse and conflicting interpretations in terms of its functionality (ritual from a Phoenician temple versus ostentation of a palatial royalty), and origin (Atlantic vs Eastern Mediterranean). New chemical (by LA-ICP-MS) and isotopic data (Pb by MC-ICP-MS) are presented in this work, which provide an alternative interpretation. The results suggest that the origins of the gold may not be thou- sands of kilometres away, in the Atlantic or the Mediterranean, but rather in the same region. We highlight geochemical similarities with the gold of the preceding 3rd Millennium BC civilization, with its main political and economic hub at Valencina de la Concepcio n, located just 2000 m from the Carambolo itself.This work is the result of the PIGMALION Projects (HAR-2010- 16210 & HAR 2017-82966-P). We are grateful to the Regional Council for Culture of Andalusia for providing access to the goldsmithing products analysed in this work and, likewise, for their graphic documentation. Our thanks also to Francisco Nocete Peramo for the photographs and figures, and to Ian Emmett for translating and proofreading this paper.Departamento de Historia II y Geografí

Achneliths generated in lava fountains of the Campo de Calatrava Volcanic Field (Ciudad Real, Spain)

We describe and discuss the origin of achneliths that occur within ash and lapilli tephra emitted by the Las Herrerías volcano of the Campo de Calatrava Volcanic Field (CCVF, Ciudad Real, Spain). These ash-size pyroclasts exhibit fluidal shapes (spheric, Pele´s tears or elongated) and an usually smooth, bright glassy surface. They are hyalocrystalline with olivine and, to a lesser extent, clinopyroxene phenocryst, embedded in a variably vesicular microlithic matrix. The finest Pele´s tears are aphiric and poorly vesicular. The pyroclasts studied are similar to those produced by the solidification of lavaspray in present-day lava fountains (e.g., Kilauea Iki eruption, 1959)Se describen y se discute la génesis de los achnelitos presentes en tefra de ceniza y lapilli emitida por el volcán Las Herrerías en la Región Volcánica de Campo de Calatrava (RVCC, Ciudad Real, España). Se trata de piroclastos de tamaño ceniza que presentan formas fluidales (esféricas, lágrimas de Pele, o elongadas) y una superficie vítrea y brillante, a menudo lisa. Los achnelitos son hialocristalinos, con fenocristales de olivino y en menor proporción de clinopiroxeno, inmersos en una matriz microlítica, variablemente vesicular. Las lágrimas de Pele más pequeñas son afíricas y escasamente vesiculares. Los piroclastos estudiados son similares a los generados por la solidificación de aeorosoles de lava en fuentes de lava actuales (p.ej., erupción Kilauea Iki, 1959