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Rationale: Control over accuracy and precision in isotope geochemical analysis is highly necessary for reliable results. Use of reference materials in Sr and Nd isotope geochemistry provides a means of validating optimal sample preparation and instrument configurations. Methods: A comprehensive data set of Sr and Nd isotope analyses of BHVO-2 reference material was obtained by thermal ionization mass spectrometry (TIMS). The intention is to assist other researchers in evaluating isotopic analyses of geological samples with similar chemical matrix. Results: 87Sr/86Sr isotope ratios analyzed in BHVO-2 reference material over 88 replicas from 2015 to the present provide an average value of 0.703485 ± 0.000024. In turn, 143Nd/144Nd isotope ratios in 62 replicas show an average value of 0.512978 ± 0.000012. The high number of analyses here presented ensures a high reproducibility over time in a non-certified material for isotopic analysis of these two elements. Conclusions: This high precision and reproducibility of Sr and Nd analysis by TIMS provide a basis for validation of analytical processes in the absence of certified reference materials and support the correlation of isotopic results between laboratories and the overall improvement in the interpretation of isotope results for geological, environmental and archeological samples., Unidad de Geocronología (CAI de Ciencias de la Tierra y Arqueometría - UCM), Unidad de Geocronología, CAI Ciencias de la Tierra y Arqueometría, TRUE, pub

Aluminosilicate/silicate and carbonate materials (pure and industrial) interacted with natural Acid Mine Drainage (AMD) under ambient conditions for different time periods in order to elucidate the chemical processes at the aluminosilicate and carbonate mineral-AMD interface. More precisely, powdered materials were subjected to macroscopic neutralization experiments (using on-line pH-measurements, Inductively Coupled Plasma Optical Emission Spectroscopy, Powder X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy), whereas interacted mm-sized single crystals were examined by means of nanoscale microscopic (in-situ Atomic Force Microscopy) and surface & bulk spectroscopic techniques (X-ray Photoelectron Spectroscopy, 12C-Rutherford Backscattering Spectroscopy, Solid-State 29Si and 27Al Magic-Angle-Spinning Nuclear Magnetic Resonance). The carbonates were proven to be more effective for neutralization of AMD, related to adequate removal of metals from the contaminated aqueous medium, but they are readily dissolved. The application of aluminosilicate/silicates showed that the removal of metals is considerably lower, and the pH stabilized at lower values, but they are more resistant. The investigation of interacted zeolite and calcite crystals revealed changes to the macrotopography, microtopography and nanotopography of surfaces. It was indicated that coupled dissolution and sorption (surface precipitation/co-precipitation, nucleation/crystal growth, adsorption or even absorption-including solid-state diffusion) phenomena occur simultaneously. Based on the experimental results, two generalized models -in nano(molecular)-scale- can be suggested regarding interaction of AMD with aluminosilicate and carbonate mineral surfaces., Ministerio de Ciencia e Innovación (MICINN), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

La aplicación de los resultados de un análisis de racemización de aminoácidos en geocronología ofrece importantes ventajas respecto a otras técnicas, al ser esta más rápida y económica. Sin embargo, como con cualquier otra técnica, la racemización no está exenta de fuentes de incertidumbres que deben ser analizadas previamente a la interpretación. En este trabajo se exponen los resultados obtenidos del análisis de racemización de un grupo de 25 gasterópodos continentales fósiles hallados en una excavación de investigación paleosismológica en el municipio de Alhama de Murcia. En particular se compara la ratio entre aminoácidos con estructura dextrógira y levógira (relación D/L) de los ácidos aspártico y glutámico. En primer lugar, se revisan las principales fuentes de incertidumbre que afectan a la racemización. Seguidamente se muestra la metodología empleada para descartar muestras y, finalmente, se aborda una interpretación preliminar de los resultados en relación con la estratigrafía local y la paleosismología., The use of the amino acid racemization technique in geochronology offers a great advantage compared to other techniques, as racemization analyses are usually much faster and cheaper. However, as in any other technique, amino acid racemization is subject to a number of uncertainties, which have to be thoroughly analysed previously to any interpretation of the data. In this work, we present. the results obtained in a group of 25 continental gastropods found in a paleoseismological trench in Alhama de Murcia (Betic Range, Spain). We carry out the comparison of dextrorotatory and levorotatory configuration (relation D/L) of the aspartic and glutamic acids. First, we review the different sources of uncertainty in the racemization process. Subsequently we show the methodology followed for discarding samples and, finally, we interpret in preliminary terms the results in relation to the local stratigraphy and paleoseismology, Ministerio de Ciencia e Innovación (MICINN), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

In this contribution we present a succinct overview of the role of Geochemistry in the Earth Sciences. Our idea is to offer a “bird’s eye” perspective of the advent of Geochemistry and its historical development and the advances and milestones in analytical techniques that led Geochemistry to its actual place in the context of Earth Sciences. Finally, we offer a summary of some relevant applications of Geochemistry in the study of a variety of geological problems., En esta contribución presentamos una visión sucinta del papel de la Geoquímica en el panorama de las Ciencias de la Tierra. Nuestra idea es mostrar una perspectiva del origen de la Geoquímica y su desarrollo histórico, así como de la evolución de las técnicas analíticas que han llevado a esta disciplina a ocupar un papel relevante en las Ciencias de la Tierra. Finalmente, ofrecemos un comentario sobre alguna de las aplicaciones más significativas de la Geoquímica en el estudio de diversos problemas geológicos., Ministerio de Ciencia e Innovación (MICINN), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

In recent years there is growing evidence of the importance of the Smithian-Spathian (Early Triassic) ecological crisis to explain the delayed recovery of life after the Permian-Triassic Boundary mass extinction. This study focuses on sedimentary continental rocks of middle Permian to Middle Triassic age from four different Peritethys basins in subequatorial latitudes. Similar distribution patterns of aluminum phosphate-sulfate (APS) minerals contents in these rocks in the four studied basins provide evidence of increased acidity during the Smithian-Spathian transition, coinciding with a lack of indicators of organic activity in the same interval. Thus, this period of high acidity on land, may have been one of the causes of this biological crisis. Based on the quantification of APS minerals in the studied sedimentary sequences, we propose that it was not until acidity in the environment diminished, that biotic recovery was possible. APS data may also be useful to interpret other past biotic crises., Ministerio de Economía y Competitividad (MINECO), Consejo Superior de Investigaciones Científicas (CSIC), Universidad Complutense de Madrid, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

En el sur de la isla de Tenerife, en el Edificio Roque del Conde, se encuentran estructuras en forma de domo denominadas “Roques”, formadas por rocas intrusivas sálicas de composiciones ácidas e intermedias, fuertemente y moderadamente alcalinas: traquiandesitas, fonolitas y traquitas. Algunos de los roques son homogéneos composicionalmente, mientras que otros varían de composición de unas zonas a otras. Las traquiandesitas siguen pautas composicionales lineales con las rocas más básicas del edificio Roque del Conde y parecen haberse formado por un proceso de cristalización fraccionada relativamente sencillo y continuo. Las traquitas y las fonolitas siguen pautas composicionales diferentes a las anteriores. Están también esencialmente controladas por procesos de cristalización fraccionada, en los que las plagioclasas y los feldespatos potásicos, en diferentes proporciones según los casos, son las fases principales extraídas. Las fases accesorias, como la titanomagnetita, la esfena y el apatito, y el anfíbol han tenido también un papel importante en estos procesos., In Roque del Conde Old Edifice at the south of Tenerife Island there are domatic structures called “roques” that are formed by intrusive salic rocks of acidic and intermediate compositions, and alkaline and strongly alkaline: trachyandesites, phonolites and trachytes. Some of the roques are compositionally homogeneous whereas others have a compositional variation in different zones. Trachyandesites follow a lineal pattern with the most basic rocks of Roque del Conde edifice and have been formed by a process of fractional crystallization. Trachytes and phonolites follow different patterns from the former. They are essentially controlled by fractional crystallization processes, where plagioclase and K-feldspars are the main removed phases. Accessory phases like Ti-magnetite, sphene and apatite, or amphibole have also an important role in these processes., Ministerio de Ciencia e Innovación (MICINN), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The North African section of the Gondwana margin was the site of voluminous, arc-related magmatism during the Late Neoproterozoic (Avalonian–Cadomian orogen). The lower (and older) metasedimentary sequence that constitutes the Basal Units of the Allochthonous Complexes of NW Iberia was deposited in that setting. In these units, sedimentation was followed by the intrusion of tonalites and granodiorites in the late Cambrian (ca. 493–489Ma). In the Late Paleozoic, the collision of Gondwana and Laurussia (Variscan orogeny) deformed and metamorphosed the whole ensemble. New whole rock geochemical analysis performed in seven samples of metatonalites and fourteen samples of metagranodiorites are characterized by: i) slight enrichment in incompatible elements (Rb, Ba, Th, U), ii) negative anomalies in Nb, Ta, P, and Ti, and iii) negative anomalies in Eu. These chemical features are in agreement with a subduction-related setting for the genesis of both types of magma, which is also supported by chemical discrimination using tectonic setting diagrams. Positive anomalies of Pb suggest a crustal component. The new geochemical data reveal that the convergent orogen that ruled the paleogeography of the Gondwana periphery during the Neoproterozoic (Cadomian orogen) remained active beyond the Neoproterozoic-Cambrian transition, up to at least late Cambrian times., Ministerio de Economía y Competitividad (MINECO), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The upper allochthonous units of NW Iberian Massif montain an extensive Cambrian magmatism (c. 500 Ma), that generated large massifs of granitic rocks and gabbros with calc-alkaline and tholeiitic compositions, respectively. Petrological and geochemical features of these massifs are characteristic of volcanic arcs. The plutons intruded siliciclastic series deposited in the periphery of the West Africa Craton. U-Pb/Hf isotopic compositions of detrital zircon in the siliciclastic series, indicate arc activity between c. 750 Ma and c. 500 Ma. It was characterized by a large variety of isotopic sources, including from very old continental input, even Archean, to the addition of a significant amount of juvenile mafic material. These isotopic sources experienced an extensive mixing that explains the composition and isotopic features of the represented Cambrian plutons. The Cambrian igneous rocks of the upper units of NW Iberia can be related to the latest activity of the Avalonian-Cadomian arc. From Middle Cambrian times, arc activity in the periphery of Gondwana was replaced by pronounced extension associated with continental rifting, which finally led to separation of the microcontinent Avalonia. Subsequent drifting of Avalonia to the North caused progressive opening of one of the main Paleozoic ocean, the Rheic Ocean., Las unidades alóctonas superiores del NW del Macizo Ibérico contienen un extenso magmatismo Cámbrico (c. 500 Ma), que generó grandes macizos de rocas graníticas y gabros, con composiciones calcoalcalinas y toleíticas, respectivamente. Las características petrológicas y geoquímicas de estos macizos son típicas de arcos volcánicos. Los plutones intruyen en series siliciclásticas depositadas en la periferia del Cratón del Oeste de África. Las relaciones isotópicas U-Pb/Hf de circones detríticos de las series siliciclásticas, indican que el arco fue activo entre c. 750 y c. 500 Ma. Originó una gran variedad de fuentes isotópicas, que incluyen desde fuentes continentales muy antiguas, incluso Arcaicas, hasta la participación de una gran cantidad de material máfico juvenil. Estas fuentes isotópicas experimentaron un amplio mixing que explica la composición y características isotópicas de los plutones Cámbricos investigados. El magmatismo Cámbrico del NW de Iberia puede relacionarse con la última actividad del arco Avaloniense-Cadomiense. A partir del Cámbrico medio, la actividad del margen activo peri-Gondwánico fue reemplazada por extensión asociada a un episodio de rifting continental, que finalmente dio lugar a la separación del microcontinente Avalonia. La deriva posterior de Avalonia hacia el norte originó la apertura progresiva de uno de los principales océanos Paleozoicos, el Océano Rheico., Ministerio de Economía y Competitividad (MINECO), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

El estudio combinado de microtermometría de inclusiones fluidas, geoquímica isotópica y petrología de las múltiples fases de dolomitización y cementación de calcita y dolomita que afectan a la Formación Reocín (Aptiense superior, noroeste de la cuenca Vasco-Cantábrica), ha permitido reconstruir la evolución de los fluidos durante la diagénesis de enterramiento y posterior exhumación orogénica de la cuenca. Durante la diagénesis temprana tuvo lugar la primera fase de dolomita (D1) y de cementos de calcita (C1, C2), a partir de fluidos meteóricos evolucionados o mezcla de fluidos. El segundo evento importante de flujo de fluidos durante el enterramiento dio lugar a la formación de dolomía de reemplazamiento (D2) y de recristalización (D3) y a cementos saddle de dolomita (D4, D5), que muestran un amplio rango de salinidades y temperaturas de nucleación relativamente bajas, lo que sugiere la interacción de fluidos que varían entre aguas marinas evolucionadas hasta salmueras altamente evaporadas. Este evento estuvo relacionado con la precipitación de sulfuros (mineralizaciones de Zn-Pb). El tercer evento de fluidos causó la precipitación de calcita (C3) que muestra muy bajas salinidades y las temperaturas de entrampamiento más altas, lo que sugiere precipitación a partir de la circulación de un fluido meteórico calentado en profundidad. La última fase diagenética está relacionada con un fluido frío, no-salino y oxidante, que causó la precipitación de calcita (C4), recristalización de la dolomita a calcita (dedolomita) y oxi-hidróxidos de Fe., Combined microthermometry of fluid inclusions, isotope geochemistry (18O, 13C, 87Sr/86Sr) and petrography of multiple phases of replacive dolomite and calcite and dolomite cements from the Upper Aptian Reocín Formation (northwestern Basque-Cantabrian basin) has allowed to reconstruct the fluid evolution during burial diagenesis and subsequent orogenic uplift of the basin. The oldest replacive dolomite (D1) and calcite cements (C1, C2) occurred during early stages of diagenesis under evolved meteoric or mixed fluids. The second important fluid event occurred during intermediate-late burial. It was accompanied by pervasive dolomitization (D2), dolomite recrystallization (D3) and saddle dolomite cements (D4, D5), which exhibit a wide range of salinities and relatively low trapping temperatures, suggesting the interaction of fluids ranging from evolved sea-water to evaporated brines. This event was accompanied by sulfide precipitation (Zn-Pb deposits). The third fluid event was accompanied by precipitation of calcite (C3) that displays very low salinities and the highest trapping temperatures, suggesting precipitation from a hot, deep-circulating meteoric fluid. Finally, the last diagenetic stage was caused by a cool, nonsaline and oxidizing fluid. This fluid precipitated calcite (C4), recrystallized dolomite to calcite (dedolomite) and formed Fe-oxyhydroxides., Ministerio de Economía y Competitividad (MINECO), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The present paper reports the first detailed petrographical and geochemical studies of hydrothermal dolomites related to MVT Zn-(FeePb) deposits in the Riopar area (Mesozoic Prebetic Basin, SE Spain), constraining the nature, origin and evolution of dolomitizing and ore-forming fluids. Mapping and stratigraphic studies revealed two stratabound dolostone geobodies connected by other patchy bodies, which replace carbonate units of Upper Jurassic to Lower Cretaceous ages. These dolostones are associated to the WeE trending San Jorge fault, indicating a main tectonic control for fluid flow. Seven different dolomite types were identified: i) matrix-replacive planar-s (ReD-I); ii) matrix-replacive planare (ReD-II); iii) planar-e sucrosic cement (SuD); iv) non-planar grey saddle dolomite cement (SaD-I) predating Zn-(FeePb) sulfides; v) non-planar milky to pinkish saddle dolomite cement (SaD-II) post-dating Zn-(FeePb) ores; vi) ore-replacive planar-e porphyrotopic (PoD); and vii) planar-s cloudy cement (CeD). Meteoric calcite types were also recognized. The different dolomite types are isotopically characterized by: i) depleted d18O (from þ25.1 to þ27.6‰ V-SMOW) and d13C (from 2.3 to þ0.9‰ V-PDB) values compared to Upper Jurassic to Lower Cretaceous limestone signature (d18O: þ27.6 to þ30.9‰ V-SMOW; d13C: þ0.5 to þ3.2‰ V-PDB); and ii) 87Sr/86Sr ratios for the main dolomitization phases (ReD and SuD: 0.70736e0.70773) close to the Jurassic and Cretaceous carbonate values (0.70723e0.70731) whereas more radiogenic values (0.70741e0.70830) for saddle dolomites (SaD) related to the Zn-(FeePb) sulfide mineralization prevailed after fluid interaction with Rb-bearing minerals. Microthermometrical studies on two-phase liquid and vapor fluid inclusion populations in planar and non-planar dolomites and sphalerite show homogenization temperatures between 150 and 250 C. These data indicate that both planar and non-planar dolomite textures formed at high-temperatures under hydrothermal co, Ministerio de Economía y Competitividad (MINECO), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Las Unidades Basales de los complejos alóctonos de Galicia incluyen rocas metamórficas paraderivadas que alternan con abundantes rocas ortoderivadas con edades comprendidas entre 500 y 470 Ma. Por su composición, tanto mineralógica como química de roca total, las rocas ortoderivadas se dividen en dos grandes grupos: uno de gneises graníticos s.l. (tonalíticos, granodioríticos y graníticos), con una composición química que transita de tipos magnesianos-cálcicos meta-aluminosos, hasta tipos férricos calcoalcalinos y alcalino-cálcicos peralumínicos; y otro segundo grupo de gneises alcalinos y peralcalinos con una composición férrico alcalina que varía de términos peralcalinos a meta-aluminosos, llegando a tener un carácter per-alumínico los tipos más diferenciados. Los gneises graníticos s.l. presentan anomalías negativas en Nb y Ta, sugiriendo su relación con un margen continental activo, mientras que las rocas alcalinas y peralcalinas están enriquecidas en elementos traza incompatibles y presentan altos contenidos en Th, Ga y Nb, característicos de magmas asociados a un régimen extensional. Esta evolución geoquímica probablemente refleja el tránsito desde un régimen geodinámico convergente caracterizado por un sistema de arcos magmáticos hacia un rifting intracontinental., The Basal Units of the allochthonous complexes of Galicia include para-derived metamorphic rocks alternating with abundant ortho-derived rocks with protolith ages ranging between 500 and 470 Ma. According to their whole-rock chemical and mineralogical composition, the ortho-derived rocks are divided in two major groups: one consisting of granitic gneisses s.l. (tonalitic, granodioritic, and granitic) with a chemical composition ranging from magnesian calcic metaluminous types to ferroan calc-alkalic and alkali-calcic peraluminous types, and a second group including alkaline and peralkaline terms, with ferroan alkalic and peralkaline to metaluminous composition, some of the most differentiated terms reaching also a peraluminous composition. The granitic gneisses s.l. show negative Nb and Ta anomalies, typical for rocks formed in an active margin, whereas the alkaline and peralkaline rocks are rich in incompatible trace elements and show a high content of Th, Ga and Nb, as expected for crustal extension-related magmas. This geochemical evolution probably reflects the switch from a convergent geodynamic setting featured by magmatic arcs to an intracontinental rifting., Ministerio de Economía y Competitividad (MINECO), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The Cameros Basin is a paleo-petroleum system formed in the north-eastern Iberian Peninsula. The basin formed during the Mesozoic Iberian Rift and was later inverted during the Alpine orogeny. Hydrothermal events took place during the post-extensional and inversion stages, producing an important impact on the thermal history of the basin. In order to determine the source rock of the petroleum system of the basin, organic matter characteristics, the petroleum generation potential and the maturity of the basin infill are determined by means of petrology and geochemical analyses. Several organic rich units of the stratigraphic record of the basin are potential source rocks for hydrocarbons generation, although their characteristics differ depending on their location. Organic matter content in the northern sector is scarce and limited to vitrinite, inertinite and solid bitumen particles. The residual total organic carbon (TOC < 1%), the low hydrocarbon potential (S2 < 0.3 mg HC/g rock, HI < 50 mg HC/g TOC), the mature to overmature thermal stages (%Ro from 1.7 to 4.6) and the presence of solid bitumen particles indicate that hydrocarbons have been already generated by these rocks. In contrast, the southern sector of the basin is characterized by abundant organic matter remnants (TOC from 2 to 17%) and immature to early oil-window thermal conditions (0.38e0.75%Ro), indicating a high hydrocarbon potential for these rocks (S2 from 11 to 123 mg HC/g and HI values from 23 to 715 mg HC/g TOC). The different evolution of the source rocks in the basin is the result of the combination of differential subsidence rates, which determine different thermal histories and of the circulation of hydrothermal fluids in the northern-central sector during the evolution of the basin., Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid, Comunidad de Madrid, Instituto Nacional del Carbón (INCAR) del Consejo Superior de Investigaciones Científicas, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The objective of this study was to determine the As and Sb contents in soils from the Murcia Region of Spain and the possible relationship between the mineralogical composition, soil properties, and As and Sb concentrations. In this study, 490 samples were selected from areas with different characteristics in order to study As and Sb variability. Results show that As and Sb concentrations are positively correlated with the phyllosilicate and quartz content but negatively correlated with the calcite content. The generic reference level (GRL) for these elements was determined according to the Spanish legislation. Established GRL values vary according to the established mineralogical groups, suggesting that GRL has to be determined considering the lithological characteristics of the study area, Spanish Ministerio de Ciencia e Innovación, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, FALSE, pub

Basajaún Etxea Cave, North Spain, contains a wide morphological and colour variety of speleothems. Most of them are composed of aragonite, but calcite speleothems are also found. Their most common colour is white, but there are also pink, green and turquoise speleothems, in different areas of the cave. Mg-rich dissolution waters from the cave's crystalline dolostone and magnesite host rock favour aragonite precipitation and drive important diagenetic changes. In this paper we will discuss how diagenesis modifies speleothem texture, mineralogy and geochemistry, causing significant changes in the colour. We also discuss how speleothems that have undergone diagenesis may also be useful indictors of paleoclimatic conditions. Our work shows that diagenesis changes the colour of the speleothems because of the mobility of the chromophore elements during this process. Along with this elemental alteration comes the loss of the primary isotopic signals of speleothems. Detailed petrological studies of speleothems should precede their analysis for palaeoclimatic reconstruction so that influence of areas affected by diagenesis can be eliminated. In addition, diagenetic signals also contain valuable information on the changes of the waters within the cave, and the overall evolution of speleothems and the cave itself., Ministerio de Ciencia e Innovación (MCINN), Gobierno de Navarra, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Mechanical compaction is the main porosity-reducing process in sandstones, including high-reservoir-quality rigid-grain sandstones. For such sandstones, the extrapolation of theoretical or experimental compaction algorithms needs calibration with rocks having well constrained burial histories. Evaluating the compaction of these rocks is achieved by comparing current intergranular volume (IGV) with depositional IGV, which is strongly dependent on sorting. However, because sandstone sorting is difficult to measure accurately, its impact on depositional porosity and compaction state is largely underestimated. We use the quartzarenites of the Oligocene Carbonera Formation in the subsurface of the hydrostatically-pressured Llanos basin to illustrate the importance of sorting when evaluating the compaction of rigid-grain sandstones. IGV and sorting were measured in core samples using a combination of transmitted-light and cathodoluminescence images, resulting in improved accuracy over standard procedures. The compaction state of clean quartzarenites at given depths is best described using IGV-versus-sorting plots, which are used to derive compaction curves for specified sorting values. The IGV-versus-sorting trends are displaced to lower IGV values with increasing burial depth. The differences in IGV caused by differences in sorting exceed the differences in IGV resulting from 1000 m of burial, illustrating the high impact of sorting when evaluating compaction. Contrasting with published experimental results, the compaction of the Llanos basin ductile-grain-poor quartzarenites is independent of grain size, and grain rearrangement is the main compaction mechanism during the first ∼1.6 km of burial. Based on the Llanos data, we have generated IGV-versus-depth curves for clean pure quartzarenites of specific sorting, which can be used to predict their maximum primary porosity up to moderate burial depths. Differences with other published burial curves are probably related to, Fundación General de la Universidad Complutense de Madrid, Cepcolsa, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Banyoles (42°08′N, 2°45′E) is the largest and deepest lake of karstic–tectonic origin in the Iberian Peninsula. The lake comprises two basins and six sub-circularly shaped sub-basins fed by subaquatic springs. Periods of intense groundwater inflow in the deepest sub-basins lead to the fluidization and re-suspension of previously deposited sediments and subsequent settling forming homogenite deposits on the southern basin intermediate platforms. The multiproxy analysis of sediment cores combined with high resolution seismic stratigraphy (3.5 kHz pinger and multi-frequency Chirp surveys) allows a precise reconstruction of depositional environments and related hydrological variability and groundwater inflow during the last ca. 7.6 cal kyr BP. According to the age model based on 137Cs, 210Pb and AMS 14C dating, homogenite deposition occurred between 7.2 and 5.5 cal kyr BP, stopped during the middle Holocene (5.5–2.8 cal kyr BP) and greatly increased during the last two millennia with a total of 17 homogenite layers individually up to 75 cm-thick. The onset of this unique sedimentation mode at ca. 3 cal kyr BP coincides with an increase in lake level, evidenced by the onlapping of fine-grained, distal sediments over coarser massive, carbonate-rich, littoral deposits. A detailed, multidisciplinary study of the homogenites (sedimentology, physical properties, high-resolution elemental geochemistry, mineral composition, grain-size, organic matter content and SEM) combined with seismic stratigraphy demonstrates that the fluidization events triggering the formation of the homogenites were caused by higher and more intense local groundwater inflow, related to increased rainfall during the Late Holocene and likely intensified by land use changes during the last millennium., Ministerio de Economía y Competitividad (MINECO), Universidad de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Phosphogypsum (PG) is a waste product of the phosphoric acid production process and contains, generally, high activity concentrations of uranium series radionuclides. This study is a contribution towards a risk assessment in areas affected by phosphate industry in SW Spain, integrating information from soil physicochemical characteristics, total and soluble potentially toxic elements (Zn, Pb, Cd, Cu, As and Fe), mineralogical composition and ecotoxicological evaluation. The applied bioassays confirmed the soil toxicity categorisation and then, it is highly recommended to complement the results from environmental chemistry with results from bioassays, in order to provide a more complete and relevant information on the bioavailability of contaminants and to characterise the risk of contaminated areas., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

This work presents a methodology to assess the environmental potential risk of soils when submitted to different conditions. The potentially toxic element (PTE) behaviour was evaluated by single chemical extractions in order to simulate four conditions: PTEs leaching under actual rainfall conditions; acid mine drainage; and an anoxic and an oxic environment. Soil pollution assessment was carried out using the contamination factor (CF) and the pollution load index (PLI) for total contents and indicators of mobility were established for each extraction: natural mobility indicator (NMI), acid mine drainage mobility indicator (AMI), oxic mobility indicator (OMI) and anoxic mobility indicator (ANMI). The total PTE content in the samples was high, and this content decreased when the distance of the sampling site to the source of contamination increased. The results obtained after the extractions suggested that the highest PTE content was extracted in the acidic medium. The mineralogical composition is an important factor that should be taken into account in the evaluation of PTE mobility, firstly because the mineral phases react differently in the proposed situations depending on their chemical nature, and secondly, because the presence of a particular phase (with different degree of reactivity) depends on the degree of weathering. The most reactive materials under oxic conditions are, in the study area, the most modern. The proposed indices may constitute a first attempt to define areas with high potential environmental risk, where urgent action is needed. In addition, the proposed methodology could be a valuable tool to prioritise these interventions., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Carbonates are the main components of Iberian Quaternary lake sediments. In this review we summarize the main processes controlling carbonate deposition in extant Iberian lakes located in Mesozoic and Tertiary carbonate-dominated regions and formed through karstic activity during the Late Quaternary. The lakes, relatively small (1 ha to 118 ha) and relatively shallow (Zmax = 11 to 40 m) provide examples of the large variability of sedimentary facies, depositional environments, and carbonate sources. Hydrology is dominated by groundwater inflow except those directly connected to the fluvial drainage. Nine lakes have been selected for this review and the main facies in palustrine, littoral and profundal environments described and interpreted. Clastic carbonates occur in all Iberian lakes due to the carbonate composition of the bedrocks, surface formations and soils of the watersheds. Low temperatures and dilute meteoric waters seem responsible for the low carbonate content of sediments in high elevation lakes in the glaciated terrains in the Pyrenees and the Cantabrian Mountains. Clastic carbonates are dominant in small karst lakes with functional inlets where sediment infill is dominated by fining upward sequences deposited during flood events. Re-working of littoral carbonates is common in shallow environments and during low lake level stages. In most lakes, endogenic carbonate production occurs in two settings: i) littoral platforms dominated by Chara and charophyte meadows and ii) epilimnetic zone as biologically-mediated calcite precipitates. Continuous preservation of varves since the Mid-Holocene only occurs in one of the deeper lakes(Montcortès Lake, up to 30 m) where calcite laminae textures (massive, fining upward and coarsening upward) reflect seasonal changes in limnological conditions. However, varves have been formed and preserved in most of the lakes during short periods associated with increased water depth and more frequent meromictic conditions. Most, Ministerio de Economía y Competitividad (MINECO), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Spinel lherzolite and wehrlite xenoliths from the Cenozoic Calatrava volcanic field carry the geochemical imprint of metasomatic agents that have affected the subcontinental lithospheric mantle beneath Central Iberia. Some xenoliths (mainly wehrlites) were enriched in REE, Sr, P, and CO2 by silicic-carbonate-rich metasomatic melts/fluids, while others record the effects of subduction-related hydrous silicate fluids that have precipitated amphibole and induced high Ti/Eu in primary clinopyroxene. The petrographic observations and geochemical data suggest that interstitial glass in the xenoliths represent the quenched products of Si-rich melts that infiltrated the mantle peridotite shortly before the entrainment of the xenoliths in the host magmas that erupted ca 2 million years ago. During their infiltration, the metasomatic melts reacted with peridotite, resulting in silica enrichment, while remobilizing grains of iron-rich monosulfide solid solution (Fe-rich Mss) initially enclosed in, or intergranular to, primary olivine and pyroxenes. In situ laser ablation inductively coupled plasma-mass spectrometry analysis of single sulfide grains reveals that the Fe-rich Mss in glass shows platinum-group element (PGE) patterns and 187Os/188Os compositions identical to the Fe-rich Mss occurring as inclusions in, or at grain boundaries of primary silicates. Moreover, independent of its microstructural position, Fe-rich Mss exhibits PGE and 187Os/188Os signatures typical of Mss either residual after partial melting or crystallized directly from sulfide melts. Our findings reveal that young metasomatic melt(s)/fluid(s) may carry remobilized sulfides with PGE and Os-isotopic signatures identical to those of texturally older sulfides in the peridotite xenolith. These sulfides thus still provide useful information about the timing and nature of older magmatic events in the subcontinental mantle., Ministerio de Ciencia e Innovación (MICINN), Junta de Andalucía, Australian Research Council Centre of Excellence, Fundación Caja Madrid, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The objective of this work was to evaluate processes affecting waters from Portman Bay by way of stable isotopic analysis, particularly H and O stable isotopes from water and S and O from dissolved sulfates. In addition, surface waters from Sierra Minera were examined for the purpose of determining if these waters are affected by similar processes. The results obtained indicate that Portman Bay waters are meteoric, and marine infiltration only takes place in the deepest layers near the shore or if water remains stagnated in sediments with low permeability. The main source of sulfate was the oxidation of sulfides, resulting in the liberation of acid, sulfate and metals. In order to assess the mechanism responsible for sulfide oxidation, the stoichiometric isotope balance model and the general isotope balance model were tested, suggesting that the oxidation via Fe3+ was predominant in the surface, and controlled by Acidithiobacillus ferrooxidans, while at depth, sulfate reduction occurred., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Palynological, sedimentological and geochemical analyses performed on the Villarquemado paleolake sequence (987 m a.s.l, 40°30′N; 1°18′W) reveal the vegetation dynamics and climate variability in continental Iberia over the last 13,500 cal yr BP. The Lateglacial and early Holocene periods are characterized by arid conditions with a stable landscape dominated by pinewoods and steppe until ca. 7780 cal yr BP, despite sedimentological evidence for large paleohydrological fluctuations in the paleolake. The most humid phase occurred between ca. 7780 and 5000 cal yr BP and was characterized by the maximum spread of mesophytes (e.g., Betula, Corylus, Quercus faginea type), the expansion of a mixed Mediterranean oak woodland with evergreen Quercus as dominant forest communities and more frequent higher lake level periods. The return of a dense pinewood synchronous with the depletion of mesophytes characterizes the mid-late Holocene transition (ca. 5000 cal yr BP) most likely as a consequence of an increasing aridity that coincides with the reappearance of a shallow, carbonate wetland environment. The paleohydrological and vegetation evolution shows similarities with other continental Mediterranean areas of Iberia and demonstrates a marked resilience of terrestrial vegetation and gradual responses to millennial-scale climate fluctuations. Human impact is negligible until the Ibero-Roman period (ca. 2500 cal yr BP) when a major deforestation occurred in the nearby pine forest. The last 1500 years are characterized by increasing landscape management, mainly associated with grazing practices shaping the current landscape., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Ciencia e Innovación (MICINN), Gobierno Vasco, Consejo Superior de Investigaciones Científicas (CSIC), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Neoproterozoic metasedimentary units from central Spain and the northern Central Iberian Zone (CIZ) show distinctive geochemical signatures with respect to the Schist-Greywacke Complex, which is dominant in the southwestern part of the CIZ. Significant differences occur in major and trace element composition and initial Nd isotope ratios, which cannot be explained in terms of metamorphic grade and/or anatexis in some layers of these metasedimentary sequences. ɛNd540 values from metapelites of central Spain range from −5.6 to −10.4 whereas those from the Schist-Greywacke Complex span a narrower and higher range of −0.8 to −3.1. This difference suggests different source regions. The presence of two contrasting Early Ordovician magmatic belts in both subzones reinforces the idea of different Precambrian basement terranes in the CIZ. These data are crucial for pre-Variscan paleogeographic reconstructions of the westernmost European terranes and for checking the validity of current subdivisions of the Iberian Massif., Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Trace element analysis of fossil bone and enamel constitutes a useful tool to characterize the paleoecological behavior of mammals. Up to now, most trace element studies have focused on Plio-Pleistocene fossils. Here, we show that paleodietary inferences based on trace element analyses can be also obtained from ~14Ma old Miocene mammals, in a period of time when important paleoclimatic changes took place due to the development of the East Antarctic ice sheet. Trace element ratio (Ba/Ca, Sr/Ca) analyses have been performed on herbivore tooth enamel (gomphothere Gomphotherium angustidens, equid Anchitherium cf. A. cursor, suid Conohyus simorrensis and ruminants) across three stratigraphic levels from the Somosaguas site (Middle Miocene, Madrid Basin, Spain). Previous scanning electron microscope, rare earth element and stable isotope analyses suggested minimal diagenetic alteration of the tooth enamel samples. Trace element analyses reported here show different paleoecological behavior among the studied fossil taxa. Anchitherium cf. A. cursor shows higher Ba/Ca and Sr/Ca ratios than Gomphotherium angustidens, indicating the equid was a mixed-feeder, while the gomphothere was a browser. The enrichment in Ba/Ca and Sr/Ca ratios in the ruminants is attributed to differences in their gastrointestinal tracts and to a more grazing diet. A high variability in trace element values characterizes the suid Conohyus simorrensis, which is believed to be connected to some degree of omnivory., Ministerio de Ciencia e Innovación (MICINN), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

En el Mioceno de la cuenca de Madrid las rocas silíceas (sílex, ópalos y sílex opalinos) son relativamente abundantes y se han utilizado durante el Paleolítico y el Neolítico para la elaboración de utensilios líticos. En el presente trabajo se establecen características químicas que sirven para definirlas y caracterizarlas de acuerdo con su localización geográfica, explicando las causas mineralógicas, petrológicas y geoquímicas que les dan su identidad. Esta caracterización resulta de gran utilidad a la hora de definir fuentes de suministro de utensilios líticos durante la Prehistoria. La caracterización mineralógica y petrológica fue realizada mediante microscopía óptica de luz transmitida, difracción de RayosX y espectrometría Raman. Los análisis químicos de elementos mayores, menores y tierras raras fueron llevados a cabo mediante espectrometría de emisión y espectrometría de masas, ambas con plasma inductivamente acoplado. En el Mioceno de la cuenca de Madrid, la mayor parte de las rocas silíceas se han generado por el reemplazamiento de rocas sedimentarias del relleno de la cuenca. Este proceso supone la disolución de la roca previa (caliza, dolomía, yeso, arcillas, etc.) y la precipitación de los minerales de SiO2 (cuarzo, fases opalinas y moganita). La composición química de los relictos de las rocas previas, junto con los elementos químicos que aportan las fases opalinas, generan una impronta geoquímica característica de cada zona muestreada (grupo de muestras), sirviendo por lo tanto para definirlas y caracterizarlas en función de su localización geográfica. El estudio estadístico de los datos obtenidos fue realizado mediante análisis bivariado (coeficientes de correlación) y multivariado (componentes principales y función discriminante). Todos los elementos químicos analizados tienen importancia en mayor o menor medida, porque cuando se plantean análisis discriminantes con menos elementos (incluso cuando sólo se eliminan aquellos de menor peso en la funció, The Miocene of the Madrid basin includes relatively abundant silica rocks (cherts, opals and opaline cherts), which were used during the Palaeolithic and Neolithic to make lithic tools. This work establishes the chemical characteristics that can be used to classify those silica rocks on the basis of their geographical location, explaining at the same time their mineralogical, petrological and geochemical features. The geographical classification of silica rocks is very useful to define the source areas of lithic tools made during the Prehistory. The mineralogical and petrological classification was made using transmitted light optical microscopy, X–Ray diffraction and Raman spectrometry. Chemical analyses of major, minor and rare elements were performed using Inductively Coupled Plasma (ICP) mass and emission spectrometry. Most of the silica rocks from the Miocene of the Madrid basin were formed by the replacement of sedimentary rocks that constitute the infill of the basin. Thisprocess implies the dissolution of the host rock (limestone, dolostone, gypsum, clays, etc.) and the precipitation of silica minerals (quartz, opalinephases and moganite). Both, the chemical composition of the host rock relicts and the elements incorporated by the opaline phases, constitutes a characteristic geochemical signature from each sampled zone (sample group). Therefore, this signature can be used to define and characterize silica rocks on the basis of their geographical location. The study of the data was carried out using bivariate analysis (i.e. correlation coefficients) and multivariate analysis (i.e. main components and the discriminant function). All the chemical elements analyzed are important in the discriminant analysis, because when fewer elements are taken into account (even when only those elements with a lower weight in the discriminant function are removed), the number of samples that can be included in the groups decreases importantly., Ministerio de Ciencia e Innovación (MICINN), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

(The original publication is available at www.springerlink.com), This work presents the results of a geochemical and geophysical characterization of the Monte Romero and La Naya mine ponds, belonging to the Cueva de la Mora and Riotinto mine districts, respectively, based on mineralogical, geochemical and geophysical techniques. In order to obtain a representative environmental characterization, two deposits showing different mineralogies, physico-chemical parameters, chemical compositions of tailings and pond conditions were selected. Monte Romero mine tailings showed an upper level mainly composed of silicates and a deeper level mainly composed of sulfides and barite. The toxic metal content was different in both levels but high enough to exceed the regional legal concentration limits for agricultural soils. An electrical resistivity tomography survey revealed a homogeneous upper unit (3 m thickness), which displayed low resistivity values, corresponding to water-saturated silt and clay materials with an abundance of sulfides which was interpreted as the pond infilling. The La Naya mine pond presented a homogeneous mineralogical composition made up of quartz as the main mineral and chlorite-smectite and jarosite as accessory phases. The absence of sulfide phases and the low contents of metal elements are directly related to the reworking processes of the sludge dumped in this pond. The geophysical survey revealed that the pond infilling did not have a constant thickness, but ranged between 15 and 20 m. An inner groundwater flow in the infilling was recognized. The low resistivity values allowed the presence of acid waters and related subsurface flows to be identified in both mine ponds, but no acid water drainage occurred across their vessels. When compared to the Aznalcóllar tailings spill, the La Naya pond is large enough to release a similar amount of sludge, but of a very low metal content. The Monte Romero sludge displays a similar, potentially toxic metal content to the Aznalcóllar sludge, but its size is significantly sm, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

A large suite of Fe–Mn nodules (561 samples) were recovered during the Anastasya 2001 cruise (TASYO project) along the continental margin of the Gulf of Cadiz (Eastern Central Atlantic), at the confluence of the Mediterranean Sea with the Atlantic Ocean, where extensive nodule fields were discovered. Based on wide previous studies that included swath bathymetry, multi-channel and very high-resolution seismic reflection, gravimetry, magnetism, heat flow probes and underwater photography surveys, nodules were collected at water depths ranging from 850 to 1000 m, associated with hydrocarbon-derived Mg-calcite, ankerite and dolomite chimneys and crusts. Forty-six selected samples among the various morphological types were used for the laboratory analysis of physical properties (morphology, color, surface texture, sphericity, weight and size), mineralogy (XRD, optical and electronic microscopy), geochemistry (XRF, AAS, ICP-MS, ICP-AES, EPMA, and GC-MS) and stable isotopes. The nodules show a wide range of sizes, densities, weights and morphologies. They are formed by multiple millimeter-thick layers of Fe and Mn oxyhydroxides surrounding the nucleus composed of Early–Middle Miocene plastic marl and sediment, which were derived from underlying units by fluid venting. Massive, laminated, detrital and mottled to dendritic textural features were developed by the Fe and Mn oxyhydroxide layers. The main components are Goethite, lepidocrocite, Mn oxides (7 Å manganates and 10 Å manganates), quartz, and phyllosilicates. Accessory minerals are calcite, dolomite, siderite, rhodochrosite, kutnahorite, pyrite, chalcopyrite, potassium feldspar, zircon, rutile, ilmenite and chlorite. Fe–Mn carbonates from the siderite–rhodochrosite continuous series are the principal constituent of the nuclei. Framboidal, filamentous and globular textures are observed in Fe–Mn oxides and pyrite, suggesting biogenic origin. The nodules show a high mean abundance of Fe (38.6%), moderate Mn (6.0%) and lo, European Science Foundation's EuroCORE–EuroMARGINS, Spanish Interministry Commission of Science and Technology (CICYT), Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The enigmatic Arequipa Massif of southwestern Peru is an outcrop of Andean basement that underwent Grenville-age metamorphism, and as such it is important for the better constraint of Laurentia–Amazonia ties in Rodinia reconstruction models. U–Pb SHRIMP zircon dating has yielded new evidence on the evolution of the Massif between Middle Paleoproterozoic and Early Paleozoic. The oldest rock-forming events occurred in major orogenic events between ca. 1.79 and 2.1 Ga (Orosirian to Rhyacian), involving early magmatism (1.89–2.1 Ga, presumably emplaced through partly Archaean continental crust), sedimentation of a thick sequence of terrigenous sediments, UHT metamorphism at ca. 1.87 Ga, and late felsic magmatism at ca. 1.79 Ga. The Atico sedimentary basin developed in the Late-Mesoproterozoic and detrital zircons were fed from a source area similar to the high-grade Paleoproterozoic basement, but also from an unknown source that provided Mesoproterozoic zircons of 1200–1600 Ma. The Grenville-age metamorphism was of low-P type; it both reworked the Paleoproterozoic rocks and also affected the Atico sedimentary rocks. Metamorphism was diachronous: ca. 1040 Ma in the Quilca and Camaná areas and in the San Juán Marcona domain, 940 ± 6 Ma in the Mollendo area, and between 1000 and 850 Ma in the Atico domain. These metamorphic domains are probably tectonically juxtaposed. Comparison with coeval Grenvillian processes in Laurentia and in southern Amazonia raises the possibility that Grenvillian metamorphism in the Arequipa Massif resulted from extension and not from collision. The Arequipa Massif experienced Ordovician–Silurian magmatism at ca. 465 Ma, including anorthosites formerly considered to be Grenvillian, and high-T metamorphism deep within the magmatic arc. Focused retrogression along shear zones or unconformities took place between 430 and 440 Ma., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

En La Gomera son frecuentes los materiales de composición sálica procedentes de diversos momentos de actividad, incluyendo depósitos piroclásticos cuya edad se desconoce. Dos coladas basálticas, intercaladas entre niveles de tobas sálicas, datadas en 6,2 ± 0,2 Ma en Jaragán y 6,6 ± 0,3 Ma en Punta Llana (mediante K-Ar), datan esa actividad piroclástica félsica del Este de la isla, permitiendo correlacionarla con el segundo episodio félsico (el más moderno) del Edificio Antiguo (Rocas Sálicas de Vallehermoso). Por otra parte, la edad obtenida mediante el método 40Ar-39Ar en el feldespato potásico de uno de los piroclastos sálicos del centro de La Gomera es de 7,90 ± 0,08 Ma, por lo que, en este caso, estos depósitos estarían relacionados con el primer episodio sálico del Edificio Antiguo (Rocas Sálicas del Este). Estas nuevas edades ponen de manifiesto que gran parte de estos materiales félsicos se emitieron durante la actividad del Edificio Antiguo y no durante el Reciente como se pensaba., Felsic materials from several activity stages are frequent in La Gomera, including pyroclastic deposits whose age is unknown. Two basaltic flows, alternated with in felsic pyroclastic fall deposits, dated in 6,2 ± 0,2 Ma in Jaragán and 6,6 ± 0,3 Ma in Punta Llana (by K-Ar method) date this felsic pyroclastic activity from East La Gomera Island, allowing us to correlate it with the second felsic episode (the youngest) of the Old Edifice (named Vallehermosos Felsic Rocks). On the other hand, the age obtained by the 40Ar-39Ar method in potassic felspars from one of the felsic pyrolcastic deposits of the central area of La Gomera is 7,90 ± 0,08 Ma, so that these deposits should be related with the first felsic episode of the Old Edifice (Eastern Felsic Rocks). These new ages reveal that most of the felsic materials were emitted during the activity of the Old Edifice and not during the Young Edifice as it was thought., Universidad Complutense / Comunidad de Madrid, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

El almacenamiento geológico profundo (AGP) es una de las iniciativas que, en el ámbito internacional, está cobrando mayor relevancia para reducir las emisiones antropogénicas de CO2 a la atmósfera. En territorio español, el estudio de las posibilidades de AGP de CO2 se está canalizando a través del Proyecto Singular Estratégico “Tecnologías avanzadas de generación, captura y almacenamiento de CO2” del MEC y, como una parte de este proyecto, se han estudiado las posibilidades que ofrece la Cuenca del Ebro de cara al almacenamiento definitivo de CO2, mediante la reinterpretación de la información de sondeos del Archivo Nacional de Hidrocarburos, gestionado por el IGME. Se han seleccionado una serie de formaciones que, por sus características relativas a disposición, extensión, profundidad y porosidad, podrían constituir un futuro almacenamiento, prestando también especial atención a las formaciones sello, que garantizarían la estanqueidad de los diferentes almacenes. Se proporciona una estimación de la capacidad de almacenamiento de cada formación, que si bien es aproximada, si puede ser un dato útil para la toma de decisiones futuras., Deep geological storage (DGS) is one of the more relevant international initiatives in order to eliminate or reduce the anthropogenic CO2 emissions to the atmosphere. The study of the possibilities of DGS of CO2 inside Spanish territory is being performed through the Strategic Singular Project “CO2 generation,capture and storage advanced technologies”, of the MEC. The potential final storage of CO2 in Ebro Basin, has been studied through reinterpretation of deep boreholes information from the National Hydrocarbons Archive, managed by IGME. A number of formations have been selected that, by their position, extent, depth and porosity, could be a future storage. The study has also been conducted considering the characteristics of the geological formations above the CO2 storage formations so as to guarantee the sealing of the storage. The study includes the approximate estimation of the storage capacity for each formation, which can be useful in future decision making., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

This research provides an ancient analogue for biologically mediated dolomite precipitation in microbial mats and biofilms, and describes the involvement of highly structured extracellular polymeric secretion (EPS) templates in dolomite nucleation. The structure of EPS is shown to match the hexagonal– trigonal lattice geometry of dolomite, which favoured the epitaxial crystallization of dolomite on the organic substrate. This structure of EPS also matches the arrangement of silica nanospheres in opal, which further accounts for the organically-templated formation of opal enabling the nonreplacive co-existence of dolomite and silica. The study is focused on a 50 m thick dolomite succession that is exposed in central areas of the Tertiary Duero Basin and was deposited in a mudflat-saline lake sedimentary complex during the Middle to Late Miocene (9 to 15 Ma). In the intermediate intervals of the succession, poorly indurated dolomite beds pass gradually into silica beds. On the basis of sedimentological, compositional, geochemical and petrographic data, silica and dolomite beds have been interpreted as mineralized microbial mats. The silica beds formed in marginal areas of the lake in response to intense evaporative concentrations; this resulted in the rapid and early precipitation of opal. Silicification accounted for the exceptional preservation of the microbial mat structure, including biofilms, filamentous and coccoid microbes, and EPS. Extracellular polymeric secretions have a layered structure, each layer being composed of fibres which are arranged in accordance with a reticular pattern, with frequent intersection angles at 120 and 60 . Therefore, the structure of EPS matches the lattice geometry of dolomite and the arrangement of silica nanospheres in opal. Additionally, EPS binds different elements, with preference to Si and Mg. The concurrence of suitable composition and surface lattice morphologies in the EPS favoured the crystallization of dolomite on the su, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Detrital zircons from Devonian and Carboniferous synorogenic flysch deposits occurring in an imbricate stack have been dated by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) to: (1) obtain a maximum depositional age to constrain the maximum age limit for thrusting of exotic terranes in the NW Iberian Massif; (2) correlate the zircon age populations with published ages in nearby units to establish their possible source areas. The maximum depositional ages are Late Devonian for rocks high in the structural nappe pile (Gimonde Formation), in accordance with palynomorph dating, and around the Devonian–Carboniferous boundary for structurally lower samples (San Vitero Formation). Used in conjunction with previously published ages, the new ages are interpreted in terms of the advance of the thrust system responsible for the emplacement of exotic terranes upon the Iberian autochthon during the Variscan collision. Early Variscan zircon population ages indicate the exotic terranes as the source of synorogenic sediments, whereas their scarcity suggests derivation from the Iberian autochthon. One of the samples analysed lacks Variscan detrital zircons; this feature, together with the absence of an Early Palaeozoic zircon age population, puts into question its synorogenic character and suggests that the sample may be representative of the preorogenic parautochthon., Spanish Ministerio de Educacio´n y Ciencia, Project IGCP 497, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

This research focuses on the development of metal pollution in sediment cores from three estuaries in Northwest Spain: Viveiro, Ortigueira and Barqueiro. Pb, Cu, Co, Cr, Cd and Zn and total organic carbon were assessed using principal component analysis (PCA) in order to obtain background values, measure pollution levels and identify pollution sources. Results were interpreted by considering the local industrial history, grain size and C/N relationship. The pollution levels obtained bear a strong resemblance to those documented for of a moderately industrialised area. PCA identifies factors that reflect mainly temporal associations with metals. Sedimentation rates between 0.9 and 1.1 cm/year were determined. In Viveiro core levels of Cr pollution are associated with tanneries. In Ortigueira, high core levels of Cu and Co are linked to mining, and Cr levels to adjacent ultramafic rocks. Erosion of Holocene sediment causes high values of Co and Cr in the Barqueiro core. Cu increase in the three estuaries is related to fungicide use since 1910. Sea level rise appears to be affecting the marine characteristics of the sediments in Barqueiro. In Viveiro, the nature of the sediment reflects engineering work and land reclamation., Ministerio de Educación y Ciencia, International Geological Correlation Programme, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Aguablanca (southwest Spain) is the first economic Ni-Cu-(PGE) deposit found in southern Europe. Two features make it an unusual example of magmatic sulfide ore: it is related to the development of an Andeantype continental magmatic arc, and it is hosted by a subvertical magmatic breccia. The structural style and the geodynamic context of the deposit contrast with most plutonic Ni-Cu-PGE deposits elsewhere, which occur at specific levels of layered mafic intrusions in rift environments. The Ni-Cu deposit is hosted by the Aguablanca intrusion, a mafic body composed of gabbronorite and minor quartz-diorite, gabbro, and norite. Sulfides are concentrated in a gabbronorite matrix along a subvertical (dipof 70º–80º N), funnel-like magmatic breccia that contains barren or slightly mineralized ultramafic-mafic cumulate fragments. Modal compositions of the fragments reflect a wide variety of rock types, including peridotite (hornblende-rich werhlite, dunite, and hornblende-rich harzburgite), pyroxenite (ortho- and clinopyroxenite), gabbro (gabbro, gabbronorite, and hornblende gabbro), and anorthosite. The primary silicate assemblage includes olivine (Fo91–Fo79), orthopyroxene (Mg no. 0.85–0.73), clinopyroxene (Mg no. 0.93–0.62), plagioclase (An99–An38), amphibole (Mg no. 0.87–0.68) and phlogopite (Mg no. 0.89–0.64). The wide range of rock types and the Fe-enrichment trends in the primary ferromagnesian silicates suggest magmatic differentiation processes from the parent melts, with the fragments representing different stages of cumulate formation. The ore-bearing breccia contains both semimassive and disseminated sulfides in the gabbronorite matrix. Textures vary between meso- and orthocumulate, and the rock-forming magmatic silicates are orthopyroxene (Mg no. 0.83–0.74), clinopyroxene (Mg no. 0.89–0.78), plagioclase (An50-An77), and intercumulus amphibole (Mg no. 0.86–0.70), phlogopite (0.84–0.69) and minor quartz. The gabbronorite in the matrix of the breccia is petrograph, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

A geochemical characterization (major, trace and rare earth element abundances) of the Lower Cretaceous sandstones of the Maestrat Basin has been carried out, in order to discriminate samples from different formations and assess their provenance and weathering conditions. All the studied sandstones are arkoses and subarkoses characterized by a multi-elemental diagram showing enrichment in Rb, U, La, Nd, Zr and Y, and depletion in Ba, Nb, Sr, P and Ti, which is typical of calc-alkaline igneous rocks. This pattern suggests an input from igneous rocks directly from the source area or by recycling. The low chemical index alteration values do not reflect intense weathering conditions in the source region. Sandstones from the studied formations were discriminated using a Rb versus Y+Nb plot. This plot shows a progressive Rb enrichment and Y+Nb depletion toward the uppermost sandstones (Camarillas Tm). Rb versus K20 indicates a good positive correlation, which is consistent with the observed Kfeldspar abundance increase towards the Camarillas sandstones. The higher SREE and Y+Nb ratios in Mora Em. sandstones suggest a slight difference in provenance, which can be explained by the contribution of Paleozoic shales and metasediments., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

The uppermost unit in Cabo Ortegal complex is composed of ultramafic rocks that crop out in three massifs: Herbeira, Limo and Uzal. Herbeira massif shows two different areas separated by a NNE-SSW fault zone. The western area is formed by a layered complex of dunites and pyroxenites which lies on top of a basal harzburgite. Amphibole-bearing peridotites and hornblendites; with aluminous spinels (Cr#<0.4), are the main lithologies in the eastern area. Hornblende is invariably present in all types of ultramafic rocks in the Herbeira massif, but the eastern peridotites mostly contain more than 15% of amphibole. Almost all ultramafic units show light rare earth elements (LREE) enriched patterns, however the basal harzburgite shows LREE-depleted patterns with negative slope while the rocks from layered complex are LREE enriched. Both ultramafic rocks from Herbeiia present marked significant Nb and Zr negative anomalies. The mineral chemistry, the REE abundances, geological and petrological data for Herbeira suggest a open-system melting to explain the formation of ultramafic rocks. The appropriate geodynamic scenario is a mantle wedge above a supra-subduction zone where the influx of an exotic fluid/melt generated in the upper parts of the subducting slab produces melting and melt extraction in the overlying mantle wedge., Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The carbonate rocks of the upper part of the Gavilán Fm from the Eastern Subbetic are studied. They have been dated as Early Pliensbachian (carixian) in age and they were deposited in a carbonate platform. The stratigraphic and facies analysis show that the general scheme proposed by Ruiz-Ortiz et al. (2004) for the middle and upper member of the formation, each of them interpreted as a depositional sequence, can be easily applied. Moreover, a third sequence can be differentiated from the unusual record of upper Carixian sediments in some of the studied sections. The evolution of the content in b,3C, b180 and 87Sr/86Sr, is also analyzed from belemnites rostra. The values of these isotope ratios range between their characteristic values for the Pliensbachian according to different authors. Some critical variations can be correlated with those proposed for equivalent ages by other authors., Grupo de Investigación RNM-200 (Junta de Andalucía), Ministerio de Ciencia y Tecnología, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

The area of Garrotxa (also known as the Olot area) represents the most recent (700,000–11,500 y) and better preserved area of magmatic activity in the NE Volcanic Province of Spain (NEVP). This region comprises a suite of intracontinental leucite basanites, nepheline basanites and alkali olivine basalts, which in most cases represent primary or nearly primary liquids. The geochemical characteristics of these lavas are very similar to the analogous petrologic types of other Cenozoic volcanics of Europe, which are intermediate between HIMU, DM and EM1. Quantitative trace element modeling, suggests derivation from an enriched mantle source by degrees of melting that progressively increased from the leucite basanites (,4%) to the olivine basalts (,16%). However, the relatively more variable Sr–Nd–Pb isotope signature of the magmas suggests the participation of at least two distinct components in the mantle source: (1) a sublithospheric one with a geochemical signature similar to the magmas of Calatrava (Central Spain) and other basalts of Europe; and (2) an enriched lithospheric component with a K-bearing phase present. The geochemical model proposed here involves the generation of a hybrid mantle lithosphere source produced by the infiltration of the sublithospheric liquids into enriched domains of the mantle lithosphere, shortly before the melting event that generated the Garrotxa lavas. The available geological data suggest that the first enrichment event of the mantle lithosphere under the NEVP could be the result of Late Variscan mantle upwelling triggered by the extensional collapse of the Variscan orogen during the Permo-Carboniferous. By Jurassic/Cretaceous time, large-scale NNE-directed sublithospheric mantle channeling of thermally and chemically anomalous plume material was placed under the Iberian Peninsula and Central Europe. However, the geodynamic conditions in the NEVP did not favor magmatism, which could not take place until the Cenozoic after extension, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub