Search results for "LCA"

Appunti per una storia dell'emigrazione albanese in Italia (secc. XIII-XVIII)

2010

The Calabrian Stage redefined

2008

The name Calabrian was introduced in the geological literature by the French stratigrapher Maurice Gignoux in 1910, and later described in his important monograph (633 pages) "Les formations marines pliocènes et quaternaires de l'Italie du sud et de la Sicile" published in 1913. Detailed data were provided on several sections (Santa Maria di Catanzaro, Caraffa, Monasterace, Palermo) and on their fossil content. The Calabrian Stage has commonly been used for over fifty years as the oldest subdivision of the Quaternary, notably in the time scales of Berggren & van Couvering (1974) and Haq & Eysinga (1987). However, after the GSSP for the Pliocene/Pleistocene boundary (P/P) was approved by INQ…

Il travertino nella costruzione muraria ad Alcamo

2022

This study describes construction features typical of masonry buildings in the historic centre of Alcamo, Sicily. This local context is significant for the extent of the historic building stock and for the large use of travertine as traditional masonry material. The local availability of this rock is a peculiarity of Alcamo, in comparison with the rest of Sicily, and its use explains the originality of several construction details. The analysis exposed in this study is part of a wider research, aimed at developing a Sicilian database of mechanical and hygrothermal data for masonry tipologies. The historic tonewalls of Alcamo have been described by means of four masonry categories, whose mai…

Euphorbia Nurae P. Fraga & Rosselló (Euphorbiaceae), a New Species from Minorca (Balearic Islands)

2011

Abstract FRAGA-ARGUIMBAU, P. & J. A. ROSSELLO (2011). Euphorbia nurae P. Fraga & Rossello (Euphorbiaceae), a new species from Minorca (Balearic Islands). Candollea 66: 181–190. In English, English and French abstracts. Euphorbia nurae P. Fraga & Rossello (Euphorbiaceae sect. Cymatospermum (Prokh.) Prokh.) is described as a new species from coastal sites of Minorca (Balearic Islands). Morphological features suggest that Euphorbia exigua L., Euphorbia dracunculoides Lam. and Euphorbia sulcata Loisel. are the most closely related taxa, but the new species can be easily discriminated by several morphological characters.

Earth Degassing in Tectonically Active Regions: New Evidences from Southern Italy and the Balkans

2022

Evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at Mount Etna (Italy): Assessment of the magmatic reservoir p…

2003

[1] Five gas discharges in the area of Mount Etna volcano (Italy) and in the near Hyblean plateau have been monitored since 1996. All the emissions displayed low contributions from crustal fluids, whereas magmatic gases were the main component. Selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled, allowing us to calculate the original composition of the magma-released gases. The inferred composition of the magmatic gases exhibits synchronous variations of He/Ne and He/CO2 ratios, which are coherent with the magma degassing process. On the basis of numerical simulations of volatile degassing from Etnean basalts we have computed the initial and final…

GEOCHEMICAL CONSTRAINTS ON THE ORIGIN OF CALCALKALINE AND ALKALINE MAGMAS OF THE EASTERN TRANS-MEXICAN VOLCANIC BELT

1988

Se presentan datos de elementos mayores, elementos trazas y tierras raras de rocas calco-alcalinas y alcalinas de la parte este del cinturón volcánico transmexicano (TMVB), así como conclusiones acerca de su origen y de su significado tectónico. Las andesitas y dacitas muestran características geoquímicas que descartan su derivación de los magmas basálticos por el proceso de cristalización fraccionada. Las distribuciones gráficas de los elementos LIL y HFS son interpretadas como indicadoras de la formación de magmas en el manto superior modificado por procesos de subducción. Las riolitas se interpretan como resultado de la fusión parcial de la corteza continental.

Syn- and post-eruptive mechanism of the Alaskan Ukinrek Maars in 1977

2008

The two alkali olivine basaltic Ukinrek Maars (East Maar and West Maar) and one scoria cone within East Maar erupted within eleven days (March 30–April 9, 1977) on the Alaskan Peninsula, 13 km north of Mt. Peulik, an andesite volcano of the Aleutian Range. The East Maar, with a diameter of 300 m, is located within a small graben system striking N 1100 E, oblique to the Aleutian trench in a distance of 350 km. On these tensional faults two eruption centres occur: The East Maar and a scoria cone on the southeastern margin of its crater bottom. The scoria cone was active more or less during the whole eruption activity of East Maar. The West Maar, with a diameter of 140 m, is located just west …

The radiogenic isotope composition of the high-latitude North Atlantic mantle

1997

New Sr, Nd, and Pb isotope data on North Atlantic high-latitude (about 69°30'N to 76°30'N) intraplate and ridge volcanic rocks, together with published data, are used to evaluate the mantle sources contributing to Iceland and the surrounding ridges. Considerable overlap between Icelandic lavas and depth-filtered North Atlantic mid-oceanic-ridge basalts (MORBs) in all isotope plots confirm that a MORB asthenosphere-plume mixing model can explain the ranges of isotope compositions found on Iceland. Regional isotope patterns north of lat 53°N show two distinct mantle domains. Lavas forming a low-radiogenic-Pb, high-radiogenic-Sr array occur north of central Iceland, whereas volcanic rocks form…

MORB-type neon in an enriched mantle beneath Etna, Sicily

1997

Abstract Noble gas elemental and isotopic compositions were determined for five CO 2 –CH 4 samples collected around Etna, Sicily, to investigate the geochemical features of the mantle beneath the volcano. The samples contain mantle-derived noble gases. The measured helium isotopic ratios ( 3 He/ 4 He) vary between 5.9 and 6.4 times atmospheric ratio ( R a =1.4×10 −6 ), which are comparable to the ratios of olivines (6.1–8.2 R a ) in the lavas of the same volcano [1]. Neon in the samples is enriched in both 20 Ne and 21 Ne ( 20 Ne/ 22 Ne 9.95–10.7, 21 Ne/ 22 Ne 0.030–0.037), indicating derivation from the mantle. The δ ( 20 Ne/ 22 Ne)/ δ ( 21 Ne/ 22 Ne) values are identical with that of mid-…