1,814 research outputs found
Platinum-group-element distribution in subcontinental mantle: evidence from the Ivrea zone (Italy) and the Betic-rifean cordillera (Spain and Morocco)
No full textThe six platinum-group elements (PGE’s) Os, Ir, Ru, Rh, Pt, and Pd and Au were analyzed by instrumental neutron-activation analysis after nickel sulfide fire assay, in peridotites and dyke rocks from the orogenic ultramafic massifs of the Ivrea Zone in the Italian western Alps (Baldissero, Balmuccia, Finero) and the Betico—Rifean cordillera in southern Spain and northern Morocco (Ronda, Beni Bousera). The peridotites are considered as variably depleted, and reenriched low lithosphere, whereas the dyke rocks represent polybaric derivatives of basaltic melts (pyroxenites and gabbros), most coming from the underlying asthenosphere. The peridotites have total PGE content in the range 8.6—54.7 ppb, while mantle-normalized patterns generally grade from nearly flat and PGE rich, in less depleted lherzolites, to negative and PGE poor, in residual harzburgites and dunites. Dyke rocks have total PGE’s in the range 5.4—250 ppb and positive mantle-normalized patterns. Negative anomalies of Ir—Pt are frequently observed in dykes, indicating that both metals were probably retained in the mantle source of these melts. Most of the peridotites display positive anomaly of Au, and in some case are enriched in Ru, Rh, and Pd, but exhibit the same negative anomalies in Ir and Pt as the dykes. These features are ascribed to réintroduction of noble metals into the residual mantle by reaction with the basaltic melts that generated the dykes, or alternatively by recycling of “dyke material” during further partial melting of the host mantle. The role of the sulfide phase as carrier of the recycled PGE is stressed by clear interelemental correlation in peridotites from the Ivrea Zone. Present data provide evidence that zones of PGE enrichment can originate this way in the subcontinental mantle, and may constitute a potential reservoir for noble metal fertile volcanism in continental rift systems
Neutron Activation analysis of Platinum Group Elements and Gold in Reference Materials: A comparison of two methods
No full textNAA of Platinum Group Elements and Gold in Reference Materials: A comparison of two methods
No full textTwo methods have been developed for the determination of platinum group elements (PGEs) and gold in four geological reference materials: one using radiochemical neutron activation analysis and the other using nickel sulphide fire assay, followed by instrumental neutron activation analysis. The results from ten multiplicate measurements have been discussed in terms of precision and accuracy. The average precision for both methods is about 5%, Comparing the reported data with existing values in the literature, the accuracy of the proposed methods is good agreement in most cases. Detection limits in the range 0,001 -0,015 ng have been derived for both methods under the operational conditions
Crack patterns induced by foundation settlements: Integrated analysis on a renaissance masonry palace in Italy
No full textThis study presents some numerical results related to the analysis of the structural damage of a historic masonry building, Palazzo Gulinelli, in Ferrara, Italy. A detailed analysis of the inhomogeneities of the facade, historic documentation, and recent restoration interventions carried out in an adjacent building, suggest that the Palace underwent various modifications both on the structural configuration and on the borne loads. Such modifications might be the main cause of some differential settlements and of the consequent significant crack pattern on the load-bearing walls. Therefore, in the present paper the occurrence of a crack pattern on the facade is simulated by carrying out standard linear and non-linear finite element (FE) homogenized models; differential settlements are applied in order to reproduce the structural changes occurred over time. Previous experiences of the authors (for example, Acito and Milani in 2012 and Mallardo et al. in 2008), the current crack pattern of the building (of its facade in particular) and the monitoring data referring to some of them are the main references for the analysis carried out. The structural survey, the numerical results, and the data monitoring suggest two main conclusions: 1) a good correlation between numerical results and monitoring data is assessed, therefore the cracks can be reasonably related to past differential settlements; and 2) the cracks/damage that occurred as a consequence of differential foundation settlements reduce the ability of the facade to resist seismic actions
Recuerdos de Massimo.
No full textEl presente ensayo recuerda la rica relación personal e intelectual entre Massimo Pavarini e Iñaki Rivera Beiras desde que el segundo conoció siendo muy joven a Pavarini. En ese sentido, el trabajo recuerda los inicios de su fecunda relación en la ciudad de Bologna cuando Iñaki Rivera acudía a presentar a Massimo Pavarini los desarrollos de lo que sería su tesis doctoral. Las contribuciones de Pavarini al proceso de aprendizaje de Rivera, en el terreno de una epistemología crítica en la penología contemporánea, son analizados como un homenaje a la memoria y a la obra del autor italiano, tras su fallecimiento en septiembre de 2015.This paper recalls the rich personal and intellectual relationship between Massimo Pavarini and Iñaki Rivera Beiras. In that sense , the work recalls the beginning of his fruitful relationship in the city of Bologna when Iñaki Rivera came to present Massimo Pavarini’ developments in what would be his PhD thesis. Pavarini contributions to the learning process of Rivera, on the ground of a critical epistemology in contemporary penology , are analyzed as a tribute to the memory and to the work of Italian author, after his death in September 2015 .El presente ensayo recuerda la rica relación personal e intelectual entre Massimo Pavarini e Iñaki Rivera Beiras desde que el segundo conoció siendo muy joven a Pavarini. En ese sentido, el trabajo recuerda los inicios de su fecunda relación en la ciudad de Bologna cuando Iñaki Rivera acudía a presentar a Massimo Pavarini los desarrollos de lo que sería su tesis doctoral. Las contribuciones de Pavarini al proceso de aprendizaje de Rivera, en el terreno de una epistemología crítica en la penología contemporánea, son analizados como un homenaje a la memoria y a la obra del autor italiano, tras su fallecimiento en septiembre de 2015
Predoni a casa nostra e il geografo solidale: Massimo Quaini tra terra e acqua
No full textIn accordance with the main goals of this collection of essays in honour of Massimo Quaini, the text focuses on a peculiar character of the Ligurian geographer’s sensibility, his attention to landscape protectionresearch activity developed in the context of the humanistic geography. Starting from a personal narrative based on his own reminiscences and neglected memories, the author tries to shed light on the relationships between civil commitment and cultural reflection which characterize environmental sensitivity, bringing together his interests with Quaini’s emotional geographies. Finally, some of Quaini’s everyday practicalities are highlighted as the easiest doorway to improve the cognitive procedures of cultural geography
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