692 research outputs found
Geometria e modellazione di un sistema di retro-scorrimenti attivosulla base di dati di geofisica marina ad alta risoluzione:la Dorsale di Amendolara (Golfo di Taranto).
Nuovi dati sismici ad alta (Sparker) ed altissima (Subbottm Chirp) risoluzione, acquisiti durante la
Campagna Oceanografica “Teatioca_2010”, integrati da dati sismici multicanale ad alta penetrazione,
pubblici disponibili sul sito www.videpi.com, calibrati con pozzi profondi, batimetrici multifascio e
carotaggi, rivelano che la dorsale di Amendolara, estensione sottomarina della zona frontale del sistema a
thrust dell’Appennino meridionale, è stata controllata nel Quaternario da un sistema di retro-scorrimenti e
faglie transpressive (ATFS) che dislocano verso SW la catena mio-pliocenica NE-vergente.
Il pacco di sequenze deposizionali attribuito, sulla base della facies sismica e della presenza di
discordanze controllate dalle oscillazioni glacio-eustatiche, al Pleistocene medio-superiore risulta piegato in
maniera consistente con le strutture desumibili dai profili multicanale. I dati morfometrici e sismici
documentano che la dorsale, orientata NW-SE, è formata da 3 banchi lunghi ~10-20 km, cresciuti sopra
rampe di sovrascorrimenti ciechi (~2 km) disposti en-echelon a formare un sistema segmentato. Sono stati
individuati e modellati i segmenti di Amendolara a NW e Cariati a SE, collegati da una più piccola rampa
laterale (segmento di Rossano). La modellazione numerica calibrata sui dati batimetrici e sismici indica che
le rampe hanno inclinazione di ~45° e sono radicate a ~10 km di profondità a possibili scollamenti o strutture
maggiori. I tassi di scorrimento negli ultimi 4-500 ka, calcolati per i segmenti sulla base degli strati di
crescita nei bacini sin tettonici variano da 0.5-0-9 mm/a per il segmento di Amendolara a 0.35-0.5 mm/a per
quello di Cariati.
L’ATFS coincide con una fascia di moderata sismicità (Mw<4.7) con meccanismi focali inversi o
transpressivi. L’orientazione degli assi di strain incrementale (sismico) e finito (geologico, come
documentano i dati a terra) suggerisce per i segmenti dell’ATFS un movimento da inverso a obliquo sinistro.
In base alla dimensione dei segmenti di faglia, nell’ipotesi di deformazione puramente elastica, si stima una
magnitudo potenziale massima per l’ATFS di M~6.1-6.4, ma è verosimile che buona parte della
deformazione sia asismica o microsismica. L’epicentro macrosismico del terremoto del 1988 (Mw=4.9)
ricade su un tratto del segmento di Cariati che mostra rotture a fondo mare e possibile risalita di fluidi
localizzata lungo strutture attive. La crescita dell’ATFS è stata verosimilmente controllata da un interfaccia
meccanica tra la spessa crosta apula e la crosta ionica assottigliata o in parte oceanica, quando in tempi
recenti la convergenza Adria-Europa ha prevalso sull’arretramento della cerniera della subduzione ionica
Morfologia e morfometria del settore ionico del Golfo di Taranto.
Il versante Ionico del Golfo di Taranto \ue8 caratterizzato dalla presenza di alti strutturali e bacini che
rappresentano l\u2019espressione morfologica di sistemi di faglie pleistoceniche transpressive. La dorsale di
Amendolara si estende per 45 Km in direzione N130\ub0E, ed \ue8 caratterizzato dalla presenza di tre alti
batimetrici minori (denominati Amendolara, Rossano e Cariati). Verso NE, la dorsale di Capo Spulico si
estende per 40 Km in direzione !N115\ub0E.
Durante la Campagna Oceanografica \u201cTeatioca\u201d sono stati acquisiti 1100Km2 di dati batimetrici
multibeam e profili sismici monocanale ad alta (Sparker) ed altissima risoluzione (Subbottom Chirp).
L\u2019analisi integrata dei nuovi dati ha consentito di ottenere una sintesi morfostrutturale preliminare dell\u2019area
sud-orientale del Golfo di Taranto [Santoro et al., 2012].
L\u2019insieme dei dati morfometrici evidenzia un ruolo chiave nell\u2019attivit\ue0 traspressiva della faglia che borda
a SW la dorsale di Amendolara, in quanto la regolarit\ue0 dei pendii rivolti a S \ue8 legata alla deformazione e
sollevamento dei versanti, che tende a superare l\u2019effetto dei processi erosivi (versanti a controllo morfostrutturale).
Il processo di basculamento guidato dall\u2019azione della faglia sembra essere all\u2019originedei processi
responsabili dell\u2019erosione gravitazionale canalizzata sui pendii esposti a nord (versanti a controllo morfosedimentario).
Sette ordini di terrazzi sono stati riconosciuti sul top del Banco di Amendolara, attraverso tecniche di
analisi dei picchi nel diagramma di distribuzione delle quote [Passaro et al., 2011]. Tale dato e le statistiche
sui profili estratti dal DTM testimoniano la presenza di tassi differenziali di sollevamento ed un complessivo
tilt (verso E) del settore frontale ionico dell\u2019Appennino Meridionale, in accordo con quanto suggerito in
letteratura [Ferranti et al., 2009].
Bibliografia
Ferranti, L., Santoro, E., Mazzella, M.E., Monaco, C., Morelli, D., (2009). Active transpression in the
northern Calabria Apennines, southern Italy. Tectonophysics, 476 (1-2), 226-251.
Passaro, S., Ferranti, L., de Alteriis, G., (2011). The use of high resolution elevation histograms for mapping
submerged terraces: a test from the Eastern Tyrrhenian Sea and the Eastern Atlantic Ocean. Quat. Int.,
232, 1-2, 238-249.
Santoro, E., Ferranti, L., Passaro, S., Burrato, P., Morelli, D., (2012). Morphometric analysis in the offshore
of the southern Taranto Gulf: unveiling the structures controlling the Late Pleistocene-Holocene
bathymetric evolution. Rend. On. Soc. Geol. It., 21 (2), 1132-1135
An active oblique-contractional belt at the transition between the Southern Apennines and Calabrian Arc: The Amendolara Ridge, Ionian Sea, Italy
High-resolution, single-channel seismic and multibeam bathymetry data collected at the
Amendolara Ridge, a key submarine area marking the junction between the Apennine collision belt and
the Calabrian subduction forearc, reveal active deformation in a supposedly stable crustal sector. New data,
integrated with existing multichannel seismic profiles calibrated with oil-exploratory wells, show that middle
to late Pleistocene sediments are deformed in growth folds above blind oblique-reverse faults that bound a
regional pop-up. Data analysis indicates that ~10 to 20 km long banks that top the ~80 km long, NW-SE
trending ridge are structural culminations above en echelon fault segments. Numeric modeling of bathymetry
and stratigraphic markers suggests that three 45\ub0 dipping upper crustal (2\u201310km) fault segments underlie the
ridge, with slip rates up to ~0.5mm/yr. Segments may be capable with M~ 6.1\u20136.3 earthquakes, although an
unknown fraction of aseismic slip undoubtedly contributes to deformation. The fault array that bounds the
southern flank of the ridge (Amendolara Fault System) parallels a belt of Mw<4.7 strike-slip and thrust
earthquakes, which suggest current left-oblique reverse motion on the array. The eastern segment of the array
shows apparent morphologic evidence of deformation and might be responsible for Mw 64 5.2 historic events.
Late Pliocene-Quaternary growth of the oblique contractional belt is related to the combined effects of stalling
of Adriatic slab retreat underneath the Apennines and subduction retreat of the Ionian slab underneath
Calabria. Deformation localization was controlled by an inherited mechanical interface between the thick
Apulian (Adriatic) platform crust and the attenuated Ionian Basin crust
Earthquake statistics and fractal faults
We introduce a Self-affine Asperity Model (SAM) for the seismicity that
mimics the fault friction by means of two fractional Brownian profiles (fBm)
that slide one over the other. An earthquake occurs when there is an overlap of
the two profiles representing the two fault faces and its energy is assumed
proportional to the overlap surface. The SAM exhibits the Gutenberg-Richter law
with an exponent related to the roughness index of the profiles. Apart
from being analytically treatable, the model exhibits a non-trivial clustering
in the spatio-temporal distribution of epicenters that strongly resembles the
experimentally observed one. A generalized and more realistic version of the
model exhibits the Omori scaling for the distribution of the aftershocks. The
SAM lies in a different perspective with respect to usual models for
seismicity. In this case, in fact, the critical behaviour is not Self-Organized
but stems from the fractal geometry of the faults, which, on its turn, is
supposed to arise as a consequence of geological processes on very long time
scales with respect to the seismic dynamics. The explicit introduction of the
fault geometry, as an active element of this complex phenomenology, represents
the real novelty of our approach.Comment: 40 pages (Tex file plus 8 postscript figures), LaTeX, submitted to
Phys. Rev.
Chemical characterization and economic evaluation of the coal fly ash pre-washing and carbonation process
In the present laboratory-scale study, the combination of washing and carbonation processes was examined to evaluate the feasibility to reduce the environmental impact of coal power plants. Three different washing solutions (tap, distilled and sea water) were used to pre-treat coal fly ash and the corresponding effect on direct gas-solid carbonation and final metal leaching was evaluated. Finally, a preliminary economic evaluation of the process was performed. In terms of captured CO2, the results have shown that significant amounts can be captured, although, as expected, the leaching of soluble salts in water such as Ca and Mg reduce the CO2 uptake. In terms of heavy metal's leaching, the application of pre-washing and carbonation treatment significantly affected the metal immobilization on the final residue. The pre-washing with sea water allowed to reach a sensible improvement since only selenium, chlorides and sulphates resulted outside the range for disposing of the carbonated residue in landfill for non-hazardous waste
An in situ intercomparison exercise on passive samplers for the monitoring of metals, polycyclic aromatic hydrocarbons and pesticides in surface water
An intercomparison exercise on passive samplers (PSs) was organized in summer 2010 for the measurement of selected metals, polycyclic aromatic hydrocarbons (PAHs) and pesticides in surface waters. Various PSs were used and compared at 2 rivers sites and one marine lagoon. A total of 24 laboratories participated. We present selected significant outputs from this exercise, including discussion on quality assurance and quality control for PSs, the interlaboratory variability of field blanks, time weighted average water concentrations and its uncertainties, the representativity of DGT samples, the ability of PSs to lower limits of detection, PAH fingerprints in various PSs compared with spot samples, and the relevance of the permeability reference compounds (PRC) approach for POCIS with pesticides. These in situ intercomparison exercises should enable to progress on the harmonization of practices for the use of passive sampling, especially for priority chemical monitoring and regulatory programs in compliance with the Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD)
Identification of na\uefve HCV-1 patients with chronic hepatitis who may benefit from dual therapy with peg-interferon and ribavirin
Background & Aims The pool of HCV genotype 1 patients likely to be cured by peg-interferon and ribavirin remains to be quantified. Methods In 1045 patients treated with peg-interferon and ribavirin, two therapeutic strategies were confronted: the first one evaluated only baseline variables associated with sustained virological response (SVR), and the second one included the rapid virologic response (RVR) in addition to baseline predictors. An 80% SVR rate was the threshold to retain a strategy as clinically relevant. Results Overall, 414 patients (39.6%) attained SVR. In the first strategy, the hierarchy of features independently associated with SVR was IL28B CC genotype (OR 5.082; CI 3.637-7.101), low (80% SVR threshold. Only 26.6% of no-RVR patients attained SVR. Among the 255 RVR patients, the likelihood of SVR was 61.8% in those with unfavorable predictors, 80% in the presence of a single predictor, and 100% when both predictors were present. By using this model, 200 patients (19.1%) were predicted to have an 80% chance of being cured with dual therapy. Conclusions A consistent subset of na\uefve HCV-1 patients, identified by some baseline characteristics and RVR, may benefit from dual treatment with peg-interferon and ribavirin. \ua9 2013 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved
Wanted dead or alive : high diversity of macroinvertebrates associated with living and ’dead’ Posidonia oceanica matte
The Mediterranean endemic seagrass Posidonia
oceanica forms beds characterised by a dense leaf canopy
and a thick root-rhizome ‘matte’. Death of P. oceanica
shoots leads to exposure of the underlying matte, which
can persist for many years, and is termed ‘dead’ matte.
Traditionally, dead matte has been regarded as a degraded
habitat. To test whether this assumption was
true, the motile macroinvertebrates of adjacent living
(with shoots) and dead (without shoots) matte of
P. oceanica were sampled in four different plots located
at the same depth (5–6 m) in Mellieha Bay, Malta
(central Mediterranean). The total number of species
and abundance were significantly higher (ANOVA;
P<0.05 and P<0.01, respectively) in the dead matte
than in living P. oceanica matte, despite the presence of
the foliar canopy in the latter. Multivariate analysis
(MDS) clearly showed two main groups of assemblages,
corresponding to the two matte types. The amphipods
Leptocheirus guttatus and Maera grossimana, and the
polychaete Nereis rava contributed most to the dissimilarity
between the two different matte types. Several
unique properties of the dead matte contributing to the
unexpected higher number of species and abundance of
motile macroinvertebrates associated with this habitat
are discussed. The findings have important implications
for the conservation of bare P. oceanica matte, which
has been generally viewed as a habitat of low ecological
value.peer-reviewe
Microspatial variability in community structure and photophysiology of calcified macroalgal microbiomes revealed by coupling of hyperspectral and high-resolution fluorescence imaging
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