Trace-element behavior during weathering of leucite in potassic rocks from the Roccamonfina volcano (Campania, southern Italy) and environmental implications     

B. Giannetti  U. Masi 《Lithos》1989,22(4):317-324

Trace-element contents in leucite and its alteration mineral phases from the Quaternary potassic rocks of the Roccamonfina volcano have been determined. The dominant weathering phase of leucite is analcite. In the early stages of the conversion process, it concentrates mainly Rb and Sr with minor amounts of Ba, Ni, V, Zn, La, Ce and Zr. At more advanced stages of the conversion process, only Rb and Y persist, while all other elements (except Cu and Cr that are essentially immobile) are lost, particularly Zn and to a lesser extent La, Ce and Nd. Besides analcite, leucite may also subordinately alter to halloysite. This probably occurs by interaction of waters of low cation/H⁺ ratio. Halloysite concentrates mainly Sr and, to a lower extent, Ba. Environmental implications are significant only for K, as the release of this element to groundwaters increases greatly the fertility of soils.  相似文献   

Geochemical and Sr–Nd isotopic evidence for the genesis of the Late Cainozoic Almopia volcanic rocks (Central Macedonia, Greece)     

G. Eleftheriadis  F. Castorina  T. Soldatos  U. Masi 《Mineralogy and Petrology》2003,78(1-2):21-36

Summary ?Major and trace element contents and Sr–Nd isotope ratios of selected volcanics of Pliocene age from the Almopia area, central Macedonia, Greece, have been determined. These rocks are mainly distinguished as two groups based on geographical, petrological and isotopic data: a) the east–central western group (E–CW) and b) the south western group (SW). The absence of contemporaneous basic volcanics in the Almopia area coupled with the considerable scatter of elements in variation diagrams rule out fractional crystallization as the dominant differentiation process. Instead, disequilibrium textures along with the positive correlation of Sr-isotope ratios with differentiation suggest mixing between a basic and an acid component combined with assimilation and fractionation. The spider diagrams of the most silica-poor volcanics show evidence of subduction-related processes, indicating that the parental magmas may have been derived from partial melting of mantle wedge enriched in LILE and LREE by subducted slab-derived fluids. Previous data on the oxygen isotope composition of the same volcanics are consistent with this genetic hypothesis. Lastly, the relatively high ⁸⁷Sr/⁸⁶Sr and low ¹⁴³Nd/¹⁴⁴Nd ratios (0.7080 and 0.512370, respectively) of the volcanic sample inferred to be compositionally the closest one to the parental magma of Almopia rocks suggest that the incompatible element enrichment of the mantle source is old, probably of Proterozoic age. Received December 12, 2001; revised version accepted June 20, 2002 Published online November 29, 2002  相似文献   

The optical performance of the PILOT instrument from ground end-to-end tests     

R. Misawa  J-Ph. Bernard  Y. Longval  I. Ristorcelli  P. Ade  D. Alina  Y. André  J. Aumont  L. Bautista  P. de Bernardis  O. Boulade  F. Bousqet  M. Bouzit  V. Buttice  A. Caillat  M. Chaigneau  M. Charra  B. Crane  F. Douchin  E. Doumayrou  J. P. Dubois  C. Engel  M. Griffin  G. Foenard  S. Grabarnik  P. Hargrave  A. Hughes  R. Laureijs  B. Leriche  S. Maestre  B. Maffei  C. Marty  W. Marty  S. Masi  J. Montel  L. Montier  B. Mot  J. Narbonne  F. Pajot  E. Pérot  J. Pimentao  G. Pisano  N. Ponthieu  L. Rodriguez  G. Roudil  M. Salatino  G. Savini  O. Simonella  M. Saccoccio  J. Tauber  C. Tucker 《Experimental Astronomy》2017,43(3):211-235

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne astronomy experiment designed to study the linear polarization of thermal dust emission in two photometric bands centred at wavelengths 240 μm (1.2 THz) and 550 μm (545 GHz), with an angular resolution of a few arcminutes. Several end-to-end tests of the instrument were performed on the ground between 2012 and 2014, in order to prepare for the first scientific flight of the experiment that took place in September 2015 from Timmins, Ontario, Canada. This paper presents the results of those tests, focussing on an evaluation of the instrument’s optical performance. We quantify image quality across the extent of the focal plane, and describe the tests that we conducted to determine the focal plane geometry, the optimal focus position, and sources of internal straylight. We present estimates of the detector response, obtained using an internal calibration source, and estimates of the background intensity and background polarization.  相似文献   

Stable isotope systematics in mesozoic granites of Central and Northern California and Southwestern Oregon     

Umberto Masi  James R. O'Neil  Ronald W. Kistler 《Contributions to Mineralogy and Petrology》1981,76(1):116-126

¹⁸O, D, and H₂O⁺ contents were measured for whole-rock specimens of granitoid rocks from 131 localitics in California and southwestern Oregon. With 41 new determinations in the Klamath Mountains and Sierra Nevada, initial strontium isotope ratios are known for 104 of these samples. Large variations in ¹⁸O (5.5 to 12.4), D (–130 to –31), water contents (0.14 to 2.23 weight percent) and initial strontium isotope ratios (0.7028 to 0.7095) suggest a variety of source materials and identify rocks modified by secondary processes. Regular patterns of variation in each isotopic ratio exist over large geographical regions, but correlations between the ratios are generally absent except in restricted areas. For example, the regular decrease in D values from west to east in the Sierra Nevada batholith is not correlative with a quite complex pattern of ¹⁸O values, implying that different processes were responsible for the isotopic variations in these two elements. In marked contrast to a good correlation between (⁸⁷Sr/⁸⁶Sr)_o and ¹⁸O observed in the Peninsular Ranges batholith to the south, such correlations are lacking except in a few areas. D values, on the other hand, correlate well with rock types, chemistry, and (⁸⁷Sr/⁸⁶Sr)_o except in the Coast Ranges where few of the isotopic signatures are primary. The uniformly low D values of samples from the Mojave Desert indicate that meteoric water contributed much of the hydrogen to the rocks in that area. Even so, the ¹⁸O values and ¹⁸O fractionations between quartz and feldspar are normal in these same rocks.This reconnaissance study has identified regularities in geochemical parameters over enormous geographical regions. These patterns are not well understood but merit more detailed examination because they contain information critical to our understanding of the development of granitoid batholiths.  相似文献   

Probabilistic and fuzzy reliability analysis of a sample slope near Aliano   总被引：13，自引：0，他引：13  

C. I. Giasi  P. Masi  C. Cherubini 《Engineering Geology》2003,67(3-4):391-402

Slope stability assessment is a geotechnical problem characterized by many sources of uncertainty. Some of them, e.g., are connected to the variability of soil parameters involved in the analysis. Beginning from a correct geotechnical characterization of the examined site, only a complete approach to uncertainty matter can lead to a significant result. The purpose of this paper is to demonstrate how to model data uncertainty in order to perform slope stability analysis with a good degree of significance.

Once the input data have been determined, a probabilistic stability assessment (first-order second moment and Monte Carlo analysis) is performed to obtain the variation of failure probability vs. correlation coefficient between soil parameters. A first result is the demonstration of the stability of first-order second moment (FOSM) (both with normal and lognormal distribution assumption) and Monte Carlo (MC) solutions, coming from a correct uncertainty modelling. The paper presents a simple algorithm (Fuzzy First Order Second Moment, FFOSM), which uses a fuzzy-based analysis applied to data processing.  相似文献   

Building damage scenarios based on exploitation of Housner intensity derived from finite faults ground motion simulations   总被引：2，自引：2，他引：0  

Leonardo Chiauzzi  Angelo Masi  Marco Mucciarelli  Marco Vona  Francesca Pacor  Giovanna Cultrera  Frantisek Gallovič  Antonio Emolo 《Bulletin of Earthquake Engineering》2012,10(2):517-545

In this paper earthquake damage scenarios for residential buildings (about 4200 units) in Potenza (Southern Italy) have been estimated adopting a novel probabilistic approach that involves complex source models, site effects, building vulnerability assessment and damage estimation through Damage Probability Matrices. Several causative faults of single seismic events, with magnitude up to 7, are known to be close to the town. A seismic hazard approach based on finite faults ground motion simulation techniques has been used to identify the sources producing the maximum expected ground motion at Potenza and to generate a set of ground motion time histories to be adopted for building damage scenarios. Additionally, site effects, evaluated in a previous work through amplification factors of Housner intensity, have been combined with the bedrock values provided by hazard assessment. Furthermore, a new relationship between Housner and EMS-98 macroseismic intensity has been developed. This relationship has been used to convert the probability mass functions of Housner intensity obtained from synthetic seismograms amplified by the site effects coefficients into probability mass function of EMS-98 intensity. Finally, the Damage Probability Matrices have been applied to estimate the damage levels of the residential buildings located in the urban area of Potenza. The proposed methodology returns the full probabilistic distribution of expected damage, thus avoiding average damage index or uncertainties expressed in term of dispersion indexes.  相似文献