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REE and Nd-isotope evidence for the origin of siderite from the Jebel Awam deposit (Central Morocco)
No full textREE contents and Nd-isotope ratios were determined in siderite ores from the "Filon du Signal" and the "Filon Sud" of the Pb-Zn-Ag mineralization of the Jebel Awam deposit, central Morocco. The deposit was formed by the intrusion of granites into the Lower Paleozoic metasedimentary basement probably by 280 Ma. The REE contents in the siderites allow for discrimination between the two veins, likely reflecting different concentrations in the mineralizing fluids. All siderites display positive Eu anomalies, indicating that the parent fluids were meta morphogenic. Assuming a common origin of the fluids, the higher REE contents and higher LREE/HREE ratios of FS siderites compared to FdS siderites suggest that the FS fluids were hotter and more acidic. The epsilon(Nd) and the Sm-147/Nd-144 ratios of the siderites range from -5.97 to -7.74, and from 0.172 to 0.183, respectively, and are statistically irrespective of sample provenance. The homogeneous isotopic data prevent use of the data forage-determination purposes, but they support the common origin of the mineralizing fluids. Moreover, since the siderites exhibit epsilon(Nd) (280 Ma) comprised between the values of the basement schists and the granites, this supports a hydrothermal origin for the mineralizing fluids. which acquired Sm and Nd by leaching both lithotypes. These conclusions, corroborating earlier information provided by Sr isotopes, demonstrate the potential of Nd isotopes and REE as geochemical tracers in the study of hydrothermal deposits. C) 2008 Elsevier B.V. All rights reserved
Sr geochemical evidence on the origin of celestite-barite deposit at Pian dell' Organo in the Tolfa Mountains area (Latium, central Italy)
No full textSr isotopic evidence for studyng the salinization of soils : an example from the San Vitale Pinewood (Ravenna)
No full textIn the frame of a multidisciplinary project of research on the San Vitale Pinewood ecosystem, north of Ravenna, the Sr isotope study of a soil profile developed on an old coastal dune aiming at detecting the effect of salinization is presented. The Sr isotope ratios of the bulk soil samples decreased significantly from upper (0.717) to lower (0.712) horizons because of the abundant marine salts deposited by the brackish water present in the deep soil. While the main source of Sr in the upper horizons is the silicates, especially the feldspaths contained in the old dune sediments; in contrast, Sr in the lower horizons is significantly also of evaporitic origin (0.707-0.709). This latter is dominantly the strontium bio-available to the plants
The Sr-isotope composition of soils: A case study from Muravera (Se Sardinia, Italy)
No full textThis paper presents a case study of applying Sr-isotope geochemistry to a soil, located near the coast in the island of Sardinia, Italy. Therefore, we have measured the Sr-isotope ratios of bulk samples from the three soil horizons as well as correlated acid extracts and insoluble residue obtained by sequential attack of bulk samples. The results indicate that the Sr isotopic compositions of acid extracts vary with depth (“vertical” isotopic trend) as well as within each horizon (“chemical” isotopic trend). Both trends can be explained assuming that bulk Sr in the soil proceeds from two reservoirs: one internal represented mainly by plagioclase of the parent rock, and the other external represented by minerals and salts carried by rainwater and winds. Calculations may provide a quantitative approach to the case study here presented
Sr isotopes and italian wines: an attempt to characterize traceability for the wine origin and marketing
No full textThe assignment of geographical origin of highly valuable products such as wine, is of considerable importance within the European Union. Conventional chemical methods of analysis are not always able to evaluate unambiguously the regional provenance of wine. Therefore, stable isotope ratio of bioelements such as C, N, O, S and isotope ratios of heavy elements (Pb and Sr) have been also applied to provide additional information of wine regional origin. The application of Sr isotopes to the characterization of wine dates as back as the ‘90s (Horns et al., 1993). In these two decades, however, no clear-cut evidence has been achieved on the thoroughly usefulness of Sr isotopes for wine characterization. In fact, isotopic ambiguity has been found for wines from certain areas throughout the world (e.g. Vorster et al., 2010). The first data of Sr-isotope ratios of Italian wines were carried out by Wolff-Bönisch et al. (1998), who reported analyses of wines from the Vesuvius and Etna volcanic districts, finding obvious differences. Recently, Mercurio et al. (2011) have determined the isotopic composition of wines from the Phlegrean Fields area, and Castorina and Masi (2011) have carried out a study of wines from Romagna. In this work, we present the Sr isotopic composition of several Italian wines aimed at evaluating the potential of this geochemical tracer of provenance. Although a larger database is needed, nevertheless, the results obtained with this study confirm that Sr isotopes can be used as a valuable tool for constraining the geographical origin of wine, at least combined with the application of other isotopic systematics and/or multi-element analysis
Caratteristiche geochimiche di acque sorgive e di pozzo della zona della piana del Fucino (L'Aquila, Italia centrale)
No full textAbundance and significance of REE's in diopside and salite clinopyroxenes from basic rocks of the Roccamonfina volcano (Roman region, Italy)
No full textThe Nd-isotope composition of siderite and its bearing for ore genesis : the case study of the Jebel Awam polymetallic deposit (central Morocco)
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Strontium geochemistry of barite from the lower Palaeozoic deposits from Tennessee and Nevada (USA)
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