Transition of Mount Etna lavas from a mantle-plume to an island-arc magmatic source.

Mount Etna lies near the boundary between two regions that exhibit significantly different types of volcanism. To the north, volcanism in the Aeolian island arc is thought to be related to subduction of the Ionian lithosphere. On Sicily itself, however, no chemical or seismological evidence of subduction-related volcanism exists, and so it is thought that the volcanism-including that on Mount Etna itself-stems from the upwelling of mantle material, associated with various surface tectonic processes. But the paucity of geological evidence regarding the primary composition of magma from Mount Etna means that its source characteristics remain controversial. Here we characterize the trace-element composition of a series of lavas emitted by Mount Etna over the past 500 kyr and preserved as melt inclusions inside olivine phenocrysts. We show that the compositional change in primary magmas from Mount Etna reflects a progressive transition from a predominantly mantle-plume source to one with a greater contribution from island-arc (subduction-related) basalts. We suggest that this is associated with southward migration of the Ionian slab, which is becoming juxtaposed with a mantle plume beneath Sicily. This implies that the volcanism of Mount Etna has become more calc-alkaline, and hence more explosive, during its evolution.

Accurate quantification of H, Li, Be, B, F, Ba, REE, Y, Th, and U in complex matrixes: a combined approach based on SIMS and single-crystal structure refinement

A procedure was developed for accurate quantification of REE, actinides, and light elements in complex matrixes of interest in earth and material sciences (hellandite and britholite, the REE analogue of apatite). These minerals show a peculiar chemical composition due to the coexistence of high amounts of LREE, U, Th with variable quantities of H, Li, Be, B, and F. Molecular interferences were resolved, and problems arising from unpredictable matrix effects and lack of reference materials were overcome. X-ray single-crystal structure refinement (SREF), which is not affected by matrix effects and does not require analytical standardization, was used to precisely estimate (by means of both site-scattering value and site geometry) in a wholly independent way the amounts and the distribution of the various groups of elements. The combined SIMS-SREF approach allowed us to obtain results of impact for mineralogy and also allowed the accuracy of SIMS investigation to be fixed. The capabilities of SIMS in the quantification of light (Z <6) and heavy (Z >57) elements as both minor and major constituents (sigmaREE(ox) up to approximately 70 wt % in britholite) are shown. This approach may open new perspectives for the in situ analysis of chemically complex materials.

[Alcoholism and the elderly: the importance of blood chemistry parameters for the diagnosis]. / Alcolismo e anziani: importanza dei parametri ematochimici per la diagnosi.

UNLABELLED: This paper again affirms the epidemiological significance of alcoholism in the elderly. The results of a study on 99 chronic alcoholic patients sixty-year older have been reported. CONCLUSIONS: The laboratory tests for diagnosis normally used for screening of alcoholism are not enough considered in the elderly. In those patients more parameters have to be evaluated.

[Rehabilitation of the elderly alcoholic]. / La riabilitazione dell'anziano alcolista.

The Authors studied 99 over 60 years old alcohol abusers, in view of their enrollment in a programme of rehabilitation. They observed that the treatment was effective, but less than it was in younger alcoholics; however, if subjects are properly selected, the efficacy is similar. In conclusion, the Authors reaffirm the importance, in spite of the difficulty, of a precocious diagnosis of alcoholism in the elderly.