The effects of ellipticity and substructure on estimates of cluster density profiles based on lensing and kinematics     

Massimo Meneghetti  Matthias Bartelmann  Adrian Jenkins  Carlos Frenk 《Monthly notices of the Royal Astronomical Society》2007,381(1):171-186

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cD galaxy contribution to the strong lensing cross-sections of galaxy clusters     

Massimo Meneghetti  Matthias Bartelmann  Lauro Moscardini 《Monthly notices of the Royal Astronomical Society》2003,346(1):67-77

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Authenticating the recovery location of meteorites: The case of Castenaso     

Luigi Folco  Massimo D'Orazio  Natale Perchiazzi 《Meteoritics & planetary science》2007,42(3):321-330

Abstract— This forensic work aims to authenticate the recovery location of Castenaso, a 120 g ordinary chondritic (L5) meteorite reportedly found in 2003 along the sandy bank of the Idice Stream, near the village of Castenaso (Bologna, Emilia‐Romagna, Italy). Using the hypothesis that Castenaso was instead a hot‐desert meteorite, we conducted a comparative mineralogical and geochemical study of major weathering effects on European and Saharan ordinary chondrites as potential markers of the environment where Castenaso resided during its terrestrial lifetime. Inductively coupled plasma‐mass spectrometry (ICP‐MS) data reveals that Castenaso is significantly enriched in Sr, Ba, Tl, and U, and suggests geochemical alteration in a hot‐desert environment. The alteration is minor: Castenaso is not coated by desert varnish and does not show significant light rare earth element (LREE) enrichment or loss of Ni and Co. The apparent contrast in size, morphology, and composition between the soil particles filling the external fractures of Castenaso and those from the bank of the Idice Stream observed under the scanning electron microscope (SEM) suggests that Castenaso did not reside at the reported find location. Abraded quartz grains (up to 1 mm in size) in Castenaso are undoubtedly from a hot‐desert eolian environment: they are well‐rounded and show external surfaces characterized by the presence of dish‐shaped concavities and upturned silica plates that have been subject to solution‐precipitation and subsequent smoothing. We therefore conclude that Castenaso is one of the many hot‐desert ordinary chondrite finds, probably from the Sahara, that is currently available on the market. This forensic work provides the scientific grounds for changing the name of this meteorite.  相似文献   

A mafic-ultramafic cumulate sequence derived from boninite-type melts (Niagara Icefalls,northern Victoria Land,Antarctica)     

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   

A refined genetic model for the Laisvall and Vassbo Mississippi Valley-type sandstone-hosted deposits,Sweden: constraints from paragenetic studies,organic geochemistry,and S,C, N,and Sr isotope data     

Nicolas J. Saintilan  Jorge E. Spangenberg  Elias Samankassou  Kalin Kouzmanov  Massimo Chiaradia  Michael B. Stephens  Lluís Fontboté 《Mineralium Deposita》2016,51(5):639-664

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Iron release in aqueous environment by fresh volcanic ash from Mount Etna (Italy) and Popocatépetl (Mexico) volcanoes     

Giancarlo Capitani  Nobuyoshi Miyajima  Roberto Sulpizio  Maria D’Addabbo  Lucia Galimberti  Massimo Guidi  Giovanni B. Andreozzi 《Environmental Earth Sciences》2018,77(13):521

In this study, we performed leaching experiments for timescales of hours-to-months in deionized water on fresh volcanic ash from Mt. Etna (Italy) and Popocatépetl (Mexico) volcanos to monitor Fe release as a function of ash mineral chemistry and size, with the aim of clarifying Fe release mechanisms and eventually evaluating the impact of volcanic ash on marine and lacustrine environments. To define sample mineralogy and Fe speciation, inclusive characterization was obtained by means of XRF, SEM, XRPD, EELS and Mössbauer spectroscopies. For Etna and Popocatépetl samples, glass proportions were quantified at 73 and 40%, Fe₂O₃ total contents at 11.6–13.2 and 5.8 wt%, and Fe³⁺/Fe_Tot ratios at 0.33 and 0.23, respectively. Leaching experiments showed that significant amounts of iron, ~?30 to 150 and ~?750 nmol g^?1 l^?1 for pristine Etna and Popocatépetl samples, respectively, are released within the first 30 min as a function of decreasing particle size (from 1 to 0.125 mm). The Popocatépetl sample showed a very sustained Fe release (up to 10 times Etna samples) all along the first week, with lowest values never below 400 nmol g^?1 l^?1 and a maximum of 1672 nmol g^?1 l^?1 recorded after 5 days. This sample, being composed of very small particles (average particle size 0.125 mm) with large surface area, likely accumulated large quantities of Fe-bearing sublimates that quickly dissolved during leaching tests, determining high Fe release and local pH decrease (that contributed to release more Fe from the glass) at short timescale (hours-to-days). The fractional Fe solubility (Fe_S) was 0.004–0.011 and 0.23% for Etna and Popocatépetl samples, respectively, but no correlation was found between Fe released in solution and either ash Fe content, glass/mineral ratio or mineral assemblage. Results obtained suggest that volcanic ash chemistry, mineralogy and particle size assume a relevant role on Fe release mostly in the medium-to-long timescale, while Fe release in the short timescale is dominated by dissolution of surface sublimates (formed by physicochemical processes occurring within the eruption plume and volcanic cloud) and the effects of such a dissolution on the local pH conditions. For all samples, a moderate to sustained Fe release occurred for leaching times comparable with their residence time within the euphotic zone of marine and lacustrine environments (variable from few minutes to few hours), revealing their possible contribution to increase Fe bioavailability.  相似文献   

Integrated use of archival aerial photogrammetry,GNSS, and InSAR data for the monitoring of the Patigno landslide (Northern Apennines,Italy)     

Cenni  Nicola  Fiaschi  Simone  Fabris  Massimo 《Landslides》2021,18(6):2247-2263

Landslides - The morphological changes of unstable areas can be identified using different methodologies that allow repeated surveys over time. The integration between the data obtained from...  相似文献   

Constraints on metasomatized mantle under Central South America: evidence from Jurassic alkaline lamprophyre dykes from the Eastern Cordillera, NM Argentina     

Natalia Hauser  Massimo Matteini  Ricardo H. Omarini  Márcio M. Pimentel 《Mineralogy and Petrology》2010,100(3-4):153-184

In the Río Grande Valley, NW Argentina, several porphyritic panidiomorphic, ocelli-bearing dykes and sills intrude the Neoproterozoic to lower Paleozoic basement of the Eastern Cordillera. New petrographical and geochemical data permit us to classify these rocks as ocellar-analcime monchiquites, a feldspar-free variety of alkaline lamprophyre composed of Ti-rich-diopside/augite, Ti-rich biotite/phlogopite, forsteritic olivine, titanian-pargasite and analcime, with abundant ocelli filled with analcime/carbonate. In terms of geochemical compositions they are characterized by LILE and LREE enrichment and lack of Nb-Ta and Eu anomalies. The ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd initial ratios range between 0.70377 to 0.70781 and 0.512506 and 0.512716 respectively, and T_DM model ages vary between 0.25–0.64 Ga. A K-Ar age of 163?±?9 Ma suggests that these rocks are related to the pre-rifting stage of the Mesozoic-Cenozoic continental Salta Rift in NW Argentina. Partial melting of a heterogeneous enriched metasomatized lithospheric mantle, magma mixing and fractionation are envisaged to explain the petrographic, geochemical and isotope characteristics of these magmas.  相似文献   

Anatomy of a late Pleistocene clinoformal sedimentary body (Le Castella,Calabria, southern Italy): A case of prograding spit system?     

Massimo Zecchin  Mauro Caffau  Dario Civile  Cesare Roda 《Sedimentary Geology》2010,223(3-4):291-309

The Le Castella marine terrace is the smallest and youngest terrace of the Crotone area (southern Italy), and formed after a rapid marine ingression due to a glacio-eustatic rise outpacing the regional uplift of the area. The most prominent feature of the terrace deposits is a seaward-accreting clinoform about 10 m thick, inferred to be formed during forced regressive conditions. This prograding body is mostly composed of bioclastic material, and shows an internal complexity consisting of alternating oblique and sigmoid elementary units inferred to be produced mainly by changes of accommodation development. Foreset avalancing was due to sediment accumulation by gravity-flow processes, while topsets were characterized by the migration of medium- to large-scale dunes showing a unimodal palaeocurrent pattern, oblique with respect to the dip direction of the large-scale clinoform foresets. The Le Castella clinoform starts to develop from a topographic step on the basement due to tectonics, which also controlled the palaeoshoreline trend.The recognized stratigraphic and facies architectures, the palaeocurrent pattern, and the inferred palaeogeographic setting during deposition, all suggest that the Le Castella clinoform is an example of spit system attached to the mainland and accreted due to longshore transport. The present example contributes to establish criteria allowing the recognition of ancient spit systems, which still are poorly known and rarely documented in the pre-Quaternary geological record.  相似文献   

Degassing, crystallization and eruption dynamics at Stromboli: trace element and lithium isotopic evidence from 2003 ashes     

Federica Schiavi  Katsura Kobayashi  Takuya Moriguti  Eizo Nakamura  Massimo Pompilio  Massimo Tiepolo  Riccardo Vannucci 《Contributions to Mineralogy and Petrology》2010,159(4):541-561

During its 1800-year-long persistent activity the Stromboli volcano has erupted a highly porphyritic (HP) volatile-poor scoriaceous magma and a low porphyritic (LP) volatile-rich pumiceous magma. The HP magma is erupted during normal Strombolian explosions and lava effusions, while the LP one is related to more energetic paroxysms. During the March–April 2003 explosive activity, Stromboli ejected two typologies of juvenile glassy ashes, namely highly vesicular LP shards and volatile-poor HP shards. Their textural and in situ chemical characteristics are used to unravel mutual relationships between HP and LP magmas, as well as magma dynamics within the shallow plumbing system. The mantle-normalized trace element patterns of both ash types show the typical arc-lava pattern; however, HP glasses possess incompatible element concentrations higher than LP glasses, along with Sr and Eu negative anomalies. HP shards are generally characterized by higher Li contents (to ~20 ppm) and lower δ⁷Li values (+1.2 to −3.8‰) with respect to LP shards (Li contents of 7–14 ppm and δ⁷Li ranging between +4.6 and +0.9‰). Fractional crystallization models based on major and trace element compositions, combined with a degassing model based on open-system Rayleigh distillation and on the assumption that ^melt/fluidD_Li > 1, show that abundant (~30%) plagioclase precipitation and variable degrees of degassing can lead the more primitive LP magma to evolve toward a differentiated (isotopically lighter) HP magma ponding in the upper conduit and undergoing slow continuous degassing-induced crystallization. This study also evidences that in March 2003 Stromboli volcano poured out a small early volume of LP magma that traveled slower within the conduit with respect to later and larger volumes of fast ascending LP magma erupted during the April 5 paroxysm. The different ascent rates and cooling rates of the two LP magma batches (i.e., pre- and post-paroxysm) resulted in small, but detectable, differences in their chemical signatures. Finally, this study highlights the high potential of in situ investigations of juvenile glassy ashes in petrologic and geochemical monitoring the volcanic activity and of Li isotopes as tracers of degassing processes within the shallow plumbing system.  相似文献