Contribution to the study of the Apulian microplate geodynamics

The fragmentation of the collisional border between the African and European plates has also originated the Apulian (Adriatic) microplate. Recent studies show the possibility of a non-unitary geodynamic evolution of this microplate: palaeomagnetic data from North-Western Greece and Southern Apulia indicate a different rotational behaviour. Between 41' and 43' latitude North, regional strike-slip fault systems cut crosswise the Adriatic basin, breaking the Adriatic block in at least two minor elements. The intense seismicity points out an active defonnational area. In the same region also other geophysical data identify a transitional zone

Geochemistry and petrology of three granitoid rock cores from the Nicaraguan Rise, Caribbean Sea : implications for its composition, structure and tectonic evolution

The Nicaraguan Rise is a major submarine structure of poorly known origin. Its lithologies have been studied from dredge hauls and land outcrops on the Greater Antilles and Central America and its structure from geophysical data. In this paper we present the first geochemical analyses for granitoids that were recovered during the 1970s from cores drilled on the Nicaragua Rise for oil prospecting. The three Nicaraguan Rise rocks are calk-alkaline granitoids, and lie in the high-K field for Caribbean granitoids similar to the Above Rocks, Jamaica and Terre Neuve, Haiti intrusions. All of these intrusions are considered to be of Late Cretaceous - Paleocene age. Key elements abundances - K, La, Ce, Nd, Hf, Zr and Sm - indicate that the three Nicaraguan Rise rocks present more affinity with mature oceanic arc rocks similar to other granitoids from the Greater Antilles rather than mature continental arcs. The Pb, Nd and Sr isotope data show no evidence of a continental component, thus indicating that the more eastern and northern submarine area of the Northern Nicaraguan Rise is not underlain by continental crust of the Chortis block. Although of similar age, the Nicaraguan Rise samples are different from the more depleted Cuban granitoids of the Sierra Maestra, though both show strong similarities in their 207Pb/204Pb composition. We postulate that the Northern Nicaraguan Rise was most likely a Caribbean oceanic arc system that may have interacted only at its margin with the continental blocks bounding the region to the west in the area of the Northern Honduran borderland

Rocas volcánicas de las series Inferior y Media del Grupo El Cobre en la Sierra Maestra (Cuba Oriental): volcanismo generado en un arco de islas tholeiítico

A set of 11 samples of igneous rocks from the lower and middle Cobre Group of the Sierra Maestra (SE Cuba) were analyzed. These rocks are volcanic and hypoabyssal bodies with porp hyritic texture and predominantly plagioclase phenocrystals. Their composition ranges from basalt to dacite and shows a tholeiitic trend with low K contents. The REE concentrations are low and, when normalized to chondrite, show a flat pattern with no relative enrichment in either LREE or HREE. In addition, these rocks present a slight enrichment in LILE and a strong Nb negative anomaly, typical of island arc tholeiites. Because of their geochemistry, the rocks of the Sierra Maestra are comparable to those of the Ke rmadec arc in the SW Pacific. Finally, the low REE content, the flat REE pattern, as well as the low uncompatible element contents, are similar to the IAT Series present in the Caribbean Volcanic Arcs. All these new data on the Pa l e ogene volcanism suggest that the tectonic models proposed for the origin of the Sierra Maestra Arc should be revised

Foreland deformational pattern in the Southern Adriatic Sea

Two major deformation belts occur in the portion of the Adriatic Sea offshore the Gargano Promontory. Although these two belts display similar characters on seismic profiles, they are different in other respects. The NE-SWtrending Tremiti Deformation Belt, located north of the Gargano Promontory, originated during the Plio-Quaternary, while the E-W-trending South Gargano Deformation Belt, located south of the Gargano Promontory, formed in a time span that goes from Eocene to early Pliocene. On the ground of structural and stratigrafic evidence these deformation belts are interpreted as originated by tectonic inversion of Mesozoic extensional faults. This inversion tectonics, of Tertiary age, can be related to the evolution of the fold-and-thrust belts that surround the Adriatic Sea. A moderate seismic activity, recorded around the Tremiti Island, and historical seismological data suggest that the whole of study area is, at present, seismically active. Therefore, this portion of the Adriatic block still represents a preferental site of deformation

Foreland tectonics in the southern Adriatic Sea

Two major deformation belts occur in the portion of the Adriatic Sea offshore the Gargano Promontory. The NE-SW - trending Tremiti Deformation Belt, located north of the Gargano Promontory, originated during the Plio- Quaternary, while the E-W-trending South Gargano Deformation Belt, located south of the Gargano Promontory, formed in a time span from Eocene to Early Pliocene. These deformation belts may have originated by tectonic inversion of Mesozoic extensional faults. This inversion tectonics, of Tertiary age, can be related to the evolution of the fold-and thrust belts surrounding the Adriatic Sea. The whole of the study area is, at present, seismically active and represents a preferential site of deformation

Pensiero Musicale e pensiero visivo: l'organizzazione visuale dello spazio nella composizione musicale

This article discusses the relationships between visual elements and compositional structures in music of the twentieth century. Starts from Debussy and Schönberg, to get to the avant-garde, examining some examples of Morton Feldam, Philip Glass and Aldo Clementi

Le Variazioni di Domenico Guaccero: un tentativo di sintassi nella musica aleatoria

prospettive della musica aleatoria e nuove semiografie sono esaminate attraverso al costruzione formale delle tre Variazioni, composte da Domenico Guaccero tra il 1967 e il 1968