1,721,023 research outputs found
SEM-EDS microanalyses of microphenocrysts of Mediterranean obsidians: a preliminary approach to source discrimination
No full textSEM-EDS non-destructive analysis allows the source discrimination of the various microphenocrysts in obsidian rocks
of the Mediterranean. Samples of six Mediterranean sources, Monte Arci (Sardinia), Palmarola, Lipari, Pantelleria, Gyali and
Melos were studied using SEM-EDS non-destructive techniques in order to obtain a data base of their microphenocryst content.
The results demonstrate that provenance of an obsidian can be distinguished on the basis of its petrography, in particular by quantitative
analyses of Fe-Mg microphenocrysts; this information is particularly useful when coupled with data obtained by other nondestructive
techniques such as glass microanalysis of artefacts (Acquafredda et al., 1999). Such investigations, carried out by
SEM, an analytical technique relatively accessible to geoarchaeologists, are relatively rapid, effective and above all non-destructive
Analisi dei disequilibri geoambientali nel "Sistema Urbano" di Bari: un'area metropolitana inserita in un territorio carsico e costiero
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The asbestos pollution in a urban system: an abandoned factory in the town of Bari (Southern Italy)
No full textThe Hercynian evolution recorded in the Calabria-Peloritani Alpine range, southern Italy. An overview
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Gochemical fractionation in migmatitic rocks from Serre granulitic terrane (Calabria, southern Italy
No full textThe Hercynian crustal section in the Serre (southem Italy) is about 20 km thick and includes sub-greenschist to granulite facies metamorphic rocks which have been used to study chemical modifications during metamorphism and migmatization. The rocks studied include: (l) Stilo phyllites and Mammola paragneisses from the upper crustal metasediments; (2) migmatitic paragneisses from the lower crustal segment that contain evidence for multi-stage melting and different degrees of partial melting and extraction of melts. The upper crustal rocks and the uppermost migmatites retain the composition of common shales. Descending to the lower levels the migmatitic metapelites show modified bulk compositions relative to common shales. The degree of chemical modification increases towards the base of the investigated section. The bulk-migmatites and the melanosomes show an enrichment in MgO, FeO*, Ti02, A1203, MnO, Sc, Y, V, Cr and REE and a depletion in Si02, K20, Na20, CaO, Rb, P, U. In the lowermost migmatitic metapelites enrichment of Th and Zr is also evident. Bulk migmatites have negative Eu anomaly which is larger in the residua. The migmatites reflect: i) diverse protolith bulk compositions, ii) the effects of hydrous melting and mica dehydration melting producing both melts crystallizing in situ and melts which were extracted, iii) a different degree of melting and of separation melt-restite, iv) different effects of rehydration on cooling. The overall geochemical features suggest that the lower migmatites were derived from a source similar to the Stilo phyllites, and that the upper migmatites from protoliths similar to the uppermost unmodified Stefanaconi paragneisses. With these assumptions the major element geochemical fractionation between restites, bulk migmatites and melts formed during the multi-stage partial melting has been modelled
Structural evidences of the high-temperature deformation in the upper part of the Hercynian lower crust in the Serre Massif (Calabria, Southern Italy)
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