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151.
Lorenzo Fedele Alberto Zanetti Vincenzo Morra Michele Lustrino Leone Melluso Riccardo Vannucci 《Contributions to Mineralogy and Petrology》2009,158(3):337-356
Trace element partition coefficients between clinopyroxenes and associated glassy matrix (Cpx/L
D) have been determined for 13 REE, HFSE4+,5+, U, Th, Sr, Pb, Sc and V from combined LA-ICP-MS/EMP analyses in selected trachytes and trachyphonolites from Campi Flegrei.
Composition of clinopyroxene and glass is pretty homogeneous in the trachyphonolites, pointing to an overall attainment of
the equilibrium conditions. In trachytes, conversely, phases show some compositional heterogeneity (due to the presence of
clinopyroxene xenocrysts) that requested a more careful petrographic and geochemical inspection of the samples to assess the
equilibrium clinopyroxene composition. In the trachyte clinopyroxenes, REE are compatible from Nd to Lu (Cpx/L
D up to 2.9), like Y, Ti, Sc and V. The Cpx/L
D for Eu is lower than those of the adjacent REE, highlighting Eu2+ contribution. High D values are also shown by U, Th, Pb, Zr, Hf, Nb and Ta relatively to basaltic and andesitic systems, whereas the D
Sr is roughly similar to that found for less evolved magmas. Trachyphonolites are characterized by an overall decrease of the
Cpx/L
D for highly-charged cations (with the exception of V), and by a slight increase of D
Sr. REE are still compatible from Nd to Lu (Cpx/L
D up to 2.1), like Ti, Y, Sc and V. This variation is also predicted for REE and Y by models based on the elastic strain theory,
being consistent with the slightly lower polymerization degree estimated for the trachyphonolites. However, the observed Cpx/L
D
(REE,Y) are matched by the modelled ones only considering very low T (≤825°C), which are believed unlikely. This mismatch cannot be attributed to effects induced by the water-rich composition
of the trachyte–trachyphonolite suite, since they would lower the observed Cpx/L
D
(REE,Y). Moreover, the anomalous inflections of measured Cpx/L
D for HREE suggests some crystal-chemical control, such as the entrance of these elements in a site distinct from M2. It is
concluded that the large Cpx/L
D determined for trachytes and trachyphonolites are likely induced by hitherto unconstrained changes of the Z3+ activities related to the composition of melt and/or solid. All these considerations strongly highlight the importance of
a direct characterization of trace element partitioning in natural samples from magmatic systems poorly characterized by experimental
studies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
152.
Fabrizio Murgia Riccardo Biddau Alessandro Concas Roberto Demontis Luca Fanfani Zeno Heilmann Cristian Lai Giuditta Lecca Eva Lorrai Marino Marrocu Vittorio Alessandro Marrone Laura Muscas Elisaveta Peneva Andrea Piras Massimo Pisu Gabriella Pusceddu Guido Satta Daniela Theis Andrea Vacca Paolo Valera Ana Melina Vallenilla Ferrara Ernesto Bonomi 《Earth Science Informatics》2009,2(1-2):5-21
GRIDA3 (Shared Resources Manager for Environmental Data Analysis and Applications) is a multidisciplinary project designed to deliver an integrated system to forge solutions to some environmental challenges such as the constant increase of polluted sites, the sustainability of natural resources usage and the forecast of extreme meteorological events. The GRIDA3 portal is mainly based on Web 2.0 technologies and EnginFrame framework. The portal, now at an advanced stage of development, provides end-users with intuitive Web-interfaces and tools that simplify job submission to the underneath computing resources. The framework manages the user authentication and authorization, then controls the action and job execution into the grid computing environment, collects the results and transforms them into an useful format on the client side. The GRIDA3 Portal framework will provide a problem-solving platform allowing, through appropriate access policies, the integration and the sharing of skills, resources and tools located at multiple sites across federated domains. 相似文献
153.
Hydrogeochemical surveys were carried out in SW Sardinia (Italy) to investigate the impact of past mining activities on the quality of groundwater. The chemistry of waters from flooded galleries, adits and dumps has been compared with that of springs and wells in the same area at sites relatively far from any mine legacy. A feature, common to all waters, is the circumneutral pH, since the carbonate formations in the area neutralise the acidity produced by the oxidation of Fe-bearing sulphide minerals in the mine impacted water. However, groundwater interacting with mine workings is degraded in quality; it shows high dissolved SO4, Zn, Cd and Pb contents. In some cases groundwater exceeds the limit established by the guidelines of the World Health Organization for Pb content in drinking water, so that groundwater is mixed before entering the local aqueducts. Results from this study suggest that more attention needs to be paid to the impact on the streams from contaminated water flowing out from some mine areas because during the dry season these streams are only fed by mine groundwater. We recommend focusing efforts to reduce the chemical contamination prior to discharge. 相似文献
154.
155.
The dynamics and the surface evolution of a post‐LGM debris‐flow‐dominated alluvial fan (Tartano alluvial fan), which lies on the floor of an alpine valley (Valtellina, Northern Italy), have been investigated by means of an integrated study comprising geomorphological field work, a sedimentological study, photointerpretation, quantitative geomorphology, analysis of ancient to modern cartography and consultation of historical documents and records. The fan catchment meteoclimatic, geological and geomorphological characteristics result in fast rates of geomorphic reorganization of the fan surface (2 km2). The dynamics of the fan are determined by the alternation of low‐return period catastrophic alluvial events dominated by non‐cohesive debris flows triggered by extreme rainstorms which caused aggradation and steepening of the fan and avulsion of its main channel, with periods of low to moderate streamflow discharge punctuated by low‐ to intermediate‐magnitude flood events, causing slower but steady topographic reworking. The most ancient parts of the fan surface date back at least to the first half of the 19th century, but most of the fan surface has been restructured after 1911, mainly during the debris‐flow‐dominated events of 1911 and 1987. Phases of rapid fan toe incision and fan degradation have been recognized; since the 1930s or 1940s, the Tartano fan has been subjected to a state of deep entrenchment and narrowing of the main trunk channel and distributary area. Post‐Little Ice Age climate change and present‐day surface uplift rates have been considered as possible explanations for the observed geomorphic evolution, but tectonic or climatic controls cannot account for the order of magnitude of the erosional pace. Anthropogenic controls plausibly override the natural ones: in particular, the building of a dam in the late 1920s, about 2 km upstream of the fan, seems to have triggered fan dissection, having altered the sediment discharge through sediment retention. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
156.
Tephrochronological study in the quaternary Val d’Agri intermontane basin (Southern Apennines,Italy)
Irene Zembo Pietro Vignola Sergio Andò Riccardo Bersezio Luigina Vezzoli 《International Journal of Earth Sciences》2011,100(1):173-187
In the south-eastern depocentre of the Val d’Agri basin (Southern Apennines), a volcanic ash layer crops out interbedded within
poorly structured alluvial fan deposits of Late Pleistocene age. Textural, depositional and pedological features of this weathered
layer suggest a primary deposition from a pyroclastic fall-out of volcanic ash. Chemical analyses of feldspars show an alkali
trachytic composition and accessory minerals association allow to correlate this tephra layer with the regionally dispersed
Y-7 marine tephra layer (Tufo Verde Epomeo eruption, Ischia volcano), dated at 56 ± 4 ka. The Val d’Agri tephra here described
for the first time was deposited during MIS Stage 3. Its recovery and characterization permit to contribute to regional correlation
of the Mediterranean climatic and volcanic events from marine to continental successions and to describe landscape evolution
of the Southern Apennines during glacial–interglacial cycles. 相似文献
157.
AN ION PROBE CONTRIBUTION TO RARE EARTH ELEMENT INVESTIGATION OF GABBRO GOG-1 USING SECONDARY ION MASS SPECTROMETRY 总被引:1,自引:0,他引:1
Luisa OTTOLINI Piero BOTTAZZI Riccardo VANNUCCI Massimo ODDONE 《Geostandards and Geoanalytical Research》1992,16(1):13-19
An updated REE measurement of Gabbro GOG-1 was carried out by means of secondary ion mass spectrometry (SIMS). The availability of high amount of rock powder allowed the sample to be well ground and homogenized before analysis. Fused glass pellets were employed for SIMS investigations. REE data were compared with new ICP-AES and NAA analyses. REE results from all employed analytical techniques show good agreement and are consistent with in-situ SIMS measurements of REE in major mineral phases forming GOG-1. Extensive homogeneity tests seem to confirm the possibility to using this rock as a reference material for earth sciences. 相似文献
158.
Riccardo Tribuzio Massimo Tiepolo Stefania Fiameni 《Contributions to Mineralogy and Petrology》2008,155(5):619-633
The layered sequence from Niagara Icefalls (northern Victoria Land, Antarctica) is related to the Cambrian-Early Ordovician
Ross Orogeny. The sequence consists of dunites, harzburgites, orthopyroxenites, melagabbronorites and gabbronorites of cumulus
origin. The Mg# of olivine, spinel, orthopyroxene and clinopyroxene from these rocks yields positive correlations, thus indicating
formation from melts that mainly evolved through fractional crystallisation. The following fractionation sequence was identified:
olivine (up to 94 mol% forsterite) + Cr-rich spinel → olivine + orthopyroxene ± spinel → orthopyroxene → orthopyroxene + anorthite-rich
plagioclase ± clinopyroxene. Clinopyroxenes retain the peculiar trace element signature of boninite melts, such as extremely
low concentrations of HREE and HFSE, and LILE enrichment over REE and HFSE. U–Pb isotope data on zircons separated from a
gabbronorite have allowed us to constrain the age of emplacement of the Niagara Icefalls sequence at ∼514 Ma. The occurrence
of inherited zircons dated at ∼538 Ma indicates that the boninitic melts experienced, at least locally, crustal contamination.
The Niagara Icefalls sequence can be related to a regional scale magmatic event that affected the eastern margin of the Gondwana
supercontinent in the Middle Cambrian. We propose that the formation of the sequence was associated with the development of
an embryonic back-arc basin in an active continental margin.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
159.
Mancini Giulia Briganti Riccardo McCall Robert Dodd Nicholas Zhu Fangfang 《Ocean Dynamics》2021,71(1):1-20
Ocean Dynamics - The mutual feedback between the swash zone and the surf zone is known to affect large-scale morphodynamic processes such as breaker bar migration on sandy beaches. To fully resolve... 相似文献
160.
Maria Rosaria Renna Riccardo Tribuzio Roberto Braga 《Contributions to Mineralogy and Petrology》2013,165(6):1073-1085
The Lower Permian complex from Bocca di Tenda (Corsica island, France) consists of a gabbroic sequence crosscut by chilled dykes ranging in composition from basalt to trachyandesite and peralkaline rhyolite. The gabbroic sequence is mostly composed of olivine gabbronorites, quartz gabbronorites/diorites locally displaying high ilmenite amounts, and hornblende-rich tonalites. The quartz gabbronorites/diorites and the hornblende-rich tonalites have similar initial εNd values (+0.9 to ?1.1) and record a fractional crystallization process driven by separation of plagioclase, pyroxene, and ilmenite. The olivine gabbronorites have slightly higher initial εNd than the quartz gabbronorites/diorites and the hornblende-rich tonalites, thereby documenting that the early evolution of the melts that gave rise to the gabbroic sequence was controlled by concomitant fractional crystallization and crustal assimilation. The trachyandesite dykes are rare and rich in dark mica. The selected trachyandesite has initial εNd of +0.4, which is slightly lower than the εNd of the basalt dykes. The basalt and the trachyandesite dykes are most likely genetically related through a process of fractional crystallization controlled by segregation of plagioclase, clinopyroxene and minor ilmenite, and assimilation of crustal material. The peralkaline rhyolites have initial εNd values ranging from +0.3 to ?0.3. Whole-rock chemical variations and trace element compositions of Na-amphibole (arfvedsonite) indicate that the peralkaline rhyolite dykes record a process of fractional crystallization mainly controlled by separation of alkali feldspar and minor ilmenite and arfvedsonite. A plausible petrogenetic hypothesis for the genesis of the peralkaline rhyolite melts implies a protracted process of fractional crystallization from the trachyandesitic melts. This fractionation process would be initially ruled by separation of plagioclase, dark mica, and minor ilmenite. An alternative hypothesis for the origin of the peralkaline rhyolite melts implies partial melting of nearly coeval amphibole-rich mafic intrusives, which formed by crustally contaminated mantle-derived melts. The genesis of the peralkaline rhyolites is in any case correlated with mantle-derived melts that experienced extensive crustal contamination. 相似文献