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

The late-Variscan peraluminous Valdepeñas pluton (southern Central Iberian Zone)

The Valdepeñas pluton is the easternmost outcrop of the Cáceres-Valdepeñas magmatic alignment (southern Central Iberian Zone). This massif is constituted by a cordierite-bearing porphyritic monzogranite and may be grouped within the so-called “Serie Mixta” granitoids. The Valdepeñas monzogranite is of magnesian [FeOt/(FeOt+MgO)~0.76], alkali-calcic [(Na2O+K2O)–CaO=7.8–8.5] and peraluminous (A/CNK=1.14–1.20). Multielemental- and REE-normalized patterns are comparable to those of similar rocks in the Nisa- Alburquerque-Los Pedroches magmatic alignment, and slightly differ from those of the Montes de Toledo batholith, both in the southern Central Iberian Zone. The U-Pb zircon age of 303±3Ma is consistent with the late-orogenic character of the intrusion and is in accordance with most of the granitic peraluminous intrusions in the southern Central Iberian Zone.  86Sr/87Sr300Ma ratios (0.707424–0.711253), εNd300Mavalues (-5.53 to -6.68) and whole-rock major and trace element compositions of the studied rocks, suggest that the parental magma of the Valdepeñas monzogranite could derive from a crustal metaigneous source. The U-Pb ages (552–650Ma) of inherited zircon cores found in Valdepeñas monzogranite samples match those often found in Lower Paleozoic metavolcanics and granitic orthogneisses of Central Iberia and, furthermore, point to Upper Neoproterozoic metaigneous basement rocks as possible protoliths at the magma source. Based on the solubility of monazite in peraluminous melts, the estimated emplacement temperature of the studied monzogranite is 742–762ºC. The results obtained in this work would contribute to a better understanding of the origin of the “Serie Mixta” granitoids

The late-Variscan peraluminous Valdepeñas pluton (southern Central Iberian Zone)

The Valdepeñas pluton is the easternmost outcrop of the Cáceres-Valdepeñas magmatic alignment (southern Central Iberian Zone). This massif is constituted by a cordierite-bearing porphyritic monzogranite and may be grouped within the so-called "Serie Mixta" granitoids. The Valdepeñas monzogranite is of magnesian [FeOt /(FeOt +MgO)~0.76], alkali-calcic [(Na2O+K2O)-CaO=7.8-8.5] and peraluminous (A/CNK=1.14-1.20) composition. Multielemental- and REE-normalized patterns are comparable to those of similar rocks in the NisaAlburquerque-Los Pedroches magmatic alignment, and slightly differ from those of the Montes de Toledo batholith, both in the southern Central Iberian Zone. The U-Pb zircon age of 303±3Ma is consistent with the late-orogenic character of the intrusion and is in accordance with most of the granitic peraluminous intrusions in the southern Central Iberian Zone. 86Sr/87Sr300Ma ratios (0.707424-0.711253), εNd300Ma values (-5.53 to -6.68) and whole-rock major and trace element compositions of the studied rocks, suggest that the parental magma of the Valdepeñas monzogranite could derive from a crustal metaigneous source. The U-Pb ages (552-650Ma) of inherited zircon cores found in Valdepeñas monzogranite samples match those often found in Lower Paleozoic metavolcanics and granitic orthogneisses of Central Iberia and, furthermore, point to Upper Neoproterozoic metaigneous basement rocks as possible protoliths at the magma source. Based on the solubility of monazite in peraluminous melts, the estimated emplacement temperature of the studied monzogranite is 742-762ºC. The results obtained in this work would contribute to a better understanding of the origin of the "Serie Mixta" granitoids

Geocronologia y geoquimica isotopica de diferentes unidades de los Complejos Aloctonos de Cabo Ortegal y Malpica-Tuy (NO de EspaNa)

Dissertation Univ. Pais VascoCentro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai

ANALYTICA CHIMICA ACTA ELSEVIER Sequential separation of light rare-earth elements, thorium and uranium by miniaturized extraction chromatography: Application to isotopic analyses of silicate rocks

International audienceA new method for the concomitant separation of the light rare-earth elements (LREEs), thorium and uranium is described, and applied to the determination of '43Nd/'MNd ratios, and concentrations of Sm, Nd, Th and U in silicate rocks, using isotope dilution and thermal ionization mass spectrometry. The proposed scheme is based on two recently introduced extraction chromatographic materials, referred to as TRU.Spec (TRansUranic-element Specific) and Ln.Spec. For most geological samples, the TRU.Spec 'resin' affords a straightforward separation of LREE, U and Th with high yield, good purity and satisfactory blank levels, on a single small (0.25 ml) column. Only Fe3+ was found to have detrimental effects on the LREE yields. For iron-rich samples, this troublesome interference was overcome by pretreatment on a short cation exchange column. Besides, a tandem column arrangement with the Ln.Spec 'resin' enables the isolation of neodymium and samarium from bulk rock solutions be made in a single run. The validity of the method is illustrated by the measurement of Sm. Nd, Th and U concentrations along with '43Nd/144Nd ratios in 15 international standard reference materials

Genesis of pyroxenite-rich peridotite at Cabo Ortegal (NW Spain). Inferences from geochemical, mineral and Pb-Sr isotopic data

International audienc

New petrological data, Rb-Sr geochronology and isotope geochemistry (Sr, Nd) of the Ventosilla pluton (Sierra de Guadarrama, Spanish Central System)

Whole rock Rb-Sr ¡sotopic analyses on granites from Ventosilla pluton yield an age of 346 ± 63 Ma, and intercept at 0.708688 ± 0.00094. This age increases the time-span of the Hercynian plutonism in the area up to 70 Ma. The presence of a complex residual mineralogy and their Sr and Nd isotopic signatures, overlapping the previous isotopic data on peraluminous granites from the Spanish Central.System, suggest melting of mainly crustal sources for the origin of this pluto