1,721,040 research outputs found
Petrogenesis and tectonic setting of volcanic rocks from the Subpelagonian ophiolitic mélange in the Agoriani area (Othrys, Greece)
No full textIn the northwestern end of the Othrys Massif, the lowermost unit of the Othrys ophiolitic complex is represented by the Agoriani Mélange, which is a typical tectono-sedimentary mélange developed at a convergent margin, and comprises ophiolite-derived turbidites and debris flow deposits including, in turn, various oceanic-crust lithotypes. The volcanic rocks recorded in the Agoriani Mélange are represented by chemically distinct rock groups.
Group 1 is characterized by MOR-type basalt and basaltic andesite, showing high-Ti geochemical affinity, and flat HFSE patterns, as well as mild LREE depletion (LaN/SmN = 0.48-0.69) coupled with an overall enrichment for HREE. The chemistry of these rocks is compatible with about 20% partial melting of an undepleted MORB-type mantle source.
Group 2 is represented by basalts whose geochemical characteristics are intermediate between typical low-Ti island arc tholeiites and pure high-Ti MORBs. Nonetheless, the strong depletion of Th, Nb, and LREE (LaN/SmN = 0.02-0.20) and the mild depletion of HFSE are consistent with the compositions of magmas generated in supra-subduction zone settings from partial melting of refractory mantle sources. In particular, these rocks are compatible with about 10% partial melting from a mantle source that had experienced about 20% previous MORB melt extraction.
Group 3 includes basaltic andesites and andesites showing chemical features typical of very low-Ti (boninitic) rocks: that is, strong depletion of HFSE and depleted, U-shaped REE patterns. The chemical features displayed by Group 3 rocks are compatible with 10 - 20% partial melting of mantle sources (enriched in LILE and LREE by subduction-derived fluids), representing the residua after Group 2 primary melt extraction.
One sample is represented by alkaline basalt, as testified by the incompatible elemental ratios, as well as the marked LILE and LREE enrichments. The overall chemical features are comparable to those of typical ocean island basalts (OIBs), and are consistent with ca. 5% partial melting of a theoretical plume source.
According to the regional reconstruction of the Neo-Tethys, the volcanic lithologies included in the Agoriani Mélange are consistent with the magmatic activities that occurred in the Pindos oceanic basin from the Permian-Triassic rifting stage and Triassic-Jurassic oceanization (including seamounts) to the Middle-Late Jurassic intra-oceanic subduction.
Group 2 basalts, in particular, correspond to basalts with peculiar chemistry sporadically found in both north and south Albania. The genesis and tectono magmatic significance of these basalts is discussed in this paper on the bases of three possible models
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Trace and ultratrace elements in grapes: Possible applications for geographical traceability
No full textIn the last decades the demand of information and criteria,
suitable for connecting products to their production regions, is
becoming more urgent in order to protect the qualitative high
level productions by forgery. Wine is one of the products that
could benefit of a scientific system of analysis able to define
its production area. Features of the association between wine
and territory is not only related to pedological but also to
geographical aspects. Currently several studies to define
markers, such as isotopic ratios of O, C, and N, able to
identify types of wine has been carried out, but they are not
suitable to univocally define a specific type of wine in
particular due to the high variability of some factors
(temperature, age of vineyard, period of such us isotopic...).
The aim of this work is to identify grape’s characteristic
parameters in the Euganei Hills area (NE of Italy) considering
that they have to be directly related to in soils and than in
vines. Euganei Hills are an ideal test site because in this zone
there is a high quantity of vines farms in soils with an high
geochemical heterogeneity.
Concentration of major (Si, Ti, Al, Fe, Mn, Mg, Ca, Na,
K, P) and trace elements (Ba, Ce, Co, Cr, La, Nb, Ni, Pb, Rb,
Sr, Th, V, Y, Zn, Zr, Cu, Ga, Nd, S, Sc) on 20 samples of soils
(collected in a range of 30-40 cm of depth) and corresponding
20 samples of grapes has been analyzed by XRF. Moreover
ICP-MS analysis has been carried out on wine grapes samples,
with more attention on rare earth elements.
In the investigated areas the grapes have shown typical
concentration ratios of some trace and ultratrace elements
suitable to identify the production areas
Geochemical and petrological study of eastern limb of Rustenburg Layered Suit (Bushveld mafic complex)
No full textSouth Africa’s Bushveld Complex is the most significant and important example of layered mafic complex in the world. It is an iconic geological site, where many generation of geologists were ventured to understand the phenomenology of intrusive magma crystallization process. The interst in Bushveld Compelex expanded
since the discovery (Merensky, 1925) of the world’s large reserve of platinum (and platinum elements group). The Complex comprises four exposed sectors - the eastern limb, the western limb, the far western limb and the northern limb, with a fifth limb, the southeastern Bethal limb, obscured by younger sediments. These sectors are formed by mafic-ultramafic layered suite at the base, a granite suite and a sequence of heterogeneous predominantly felsic volcanic rocks of the Rooiberg Group. Both extrusive and intrusive Bushveld magmatism occurred with a time span of a few million years around 2057±3 (Mungall et al., 2016). The majority of the
ore deposits are, however, restricted to the intervening group of ultramafic-mafic rocks, or Rustenburg Layered Suite. The Rustenburg layered Suite comprises a package of rocks which range in composition from dunite to diorite. This layered suite is subdivided into marginal, lower (LZ), critical (CZ), main (MZ) and upper (UZ)
zones, although their exact boundaries have been the subject of much debate (e.g. Kruger, 2005). Despite the countless published papers since the Twenties of the previous century, there is no consensus yet on the details of its mode of formation. However, it is generally assumed that the layered rocks represent an upward-aggrading pile of crystals deposited on the floor of a vast, long-lived and repeatedly replenished magma chamber (e.g. Mungall et al., 2016). In 1998 the field excursion poposed by the programme of four-yearly International Vocanic Congress (IAVCEI), held in Cape Town (SA), was focused on the eastern limb of the Rustenburg Layered Suite. Petrologists of the Unviersity of Ferrara (Luigi Beccaluva and Franca Siena) attended the field excursion and collected 31 samples representing all the main rock types of each zone (dunites, orthpyroxenites, pyroxenites, anorthosites). This rock collection remained unworked for many years and just recentely were resumed by
the authors of this contribution. Here, the initial stage of a geochemical and petrological study of eastern limbof Rustenburg Layered Suite is presented. On the basis of preliminary bulk geochemistry (major and trace elements) and mineral modal distribution, the majority of the samples are cumulates: dunites, orthopyroxenites,
peridotites norite, anorthosites, gabbros; a few metasedimentary rocks of the Transvaal basement are also included. The general order of appearance (and disappearce) of cumulus minerals suggests a multiple a crystallization processes in an open melt-filled chamber.
Kruger F.J. (2005) - Filling the Bushveld Complex magma chamber: lateral expansion, roof and floor interaction, magmatic unconformities, and the formation of giant chromitite, PGE and Ti-V-magnetitite deposits. Miner. Deposita,
40, 451-472.
Merensky H. (1925) - How we discovered platinum. Mining Ind. Mag. South. Africa, 1, 265-266.
Mungall J.E. et al. (2016) - U-Pb geochronology documents out-of-sequence emplacement of ultramafic layers in the
Bushveld Igneous Complex of South Africa. Nat. Commun., 7, 13385
Geographical origin of Vitis vinifera cv. Cannonau established by the index of bioaccumulation and translocation coefficients
No full textGeochemical fingerprints in grape require an identification of major and trace elements that show correlations between concentrations in soil and in plant tissues: these correlations are relevant to discriminate grapes according to geographical origin. The Vitis vinifera cultivar Cannonau is used to produce the renowned Italian controlled designation of origin (DOC) wine Cannonau from Sardinia. Two Cannonau vineyards located in Sardinia Region were studied to establish the relationship between geochemical features of vineyard soil and chemical composition of leaves and grape berries. Major and trace elements were determined by X-ray fluorescence and inductively coupled plasma-mass spectrometry in soil, leaf, and grape berry samples. The index of bioaccumulation and the translocation coefficients were also calculated for all elements. Data from the two study areas were compared by a non-parametric test and multivariate statistics (principal component analysis). The results showed a specific assimilation of these elements in leaf and grape berry from vine in two different soils. Moreover, geochemical characterization and statistical analysis enabled to discriminate the cultivar Cannonau according to geographical origin. The results showed that the elements that could establish a reliable correlation between the soil vineyard and leaves and grape berries from the two study areas were B, Sr, and Zr. These elements may therefore be used as geochemical fingerprints to identify the geographic origin of V. vinifera cv. Cannonau in the two study areas
Outdoor science experiments, hands-on learning in nature: the Nirano Mud Volcano (NMV, Fiorano Modenese, Italy) open-field laboratory
No full textMud volcanoes (MVs) are part of the “sedimentary volcanism” due to their morphological resemblance
to igneous volcanoes and are characterized by the uplift of sediments and fluids (Martinelli & Judd, 2004;
Mazzini & Etiope, 2017). They are widely diffused and, although not always as fascinating as “ordinary”
volcanoes, no less investigated by various disciplines, e.g. botanics, microbiology, geophysics, geomorphology,
geochemistry and structural geology. In particular, they are taken into account for hydrocarbon prospection,
mainly gas, since they are mostly located in petroliferous basins and constitute the second natural source of
CH4 (Sciarra et al., 2019) and as earthquake precursors (Martinelli & Judd, 2004).
In Italy, MVs occur in both Northern and Central Apennine and in Sicily (Martinelli & Judd, 2004; Sciarra
et al., 2019). Nirano mud volcano (NMV) of the Emilia Romagna region is one of the biggest in Italy, situated
close to a small anticline in the outcrop of the Plio-Pleistocene “Argille Azzurre” clays (Martinelli & Judd,
2004), and is widely investigated for the gas composition (Mazzini & Etiope, 2017). Thousands of people of all
ages and levels of education visit this magnificent area every year. Master geology students from the University
of Ferrara, the course “geochemical prospecting”, have been putting into practice the theoretical geochemical
skills of measuring in-situ temperature, pH, and electrical conductivity, as well as collecting water and mud
samples for analyses (X-Ray Fluorescence, XRF; Inductively Coupled Plasma Mass Spectrometry, ICP-MS;
Ion Chromatography, IC; Elemental Analyzer for coupling to Isotope Ratio Mass Spectrometers, EA-IRMS)
in the laboratory.
The results of their curiosity and abilities focused on the geochemical composition of NMV mud and
water, as shown during the second Italian Geochemistry Society congress. The aim of this work is also to
raise and increase awareness of peculiar geochemical threats in the national territory at many levels using the
NMV area as an open-field laboratory, which is suitable for everyone interested in improving their geological
knowledge and understanding and the processes occurring in the Earth crust (fault formation, fluid circulation,
and earthquake indicators). In particular, this outdoor experience fits very well with exploring teens, who can
make first-hand observations, mud, water and gas sampling (be prepared to get hands dirty!) and experience
simple analyses on the field, such as pH, EC, and water salinity measurement throughout specific probes.
Martinelli G. & Judd A. (2004) - Mud volcanoes of Italy. Geol. J., 39, 49-61, https://doi.org/10.1002/gj.943.
Mazzini A. & Etiope G. (2017) - Mud volcanism: An updated review. Earth-Sci. Rev., 168, 81-112, https://doi.
org/10.1016/j.earscirev.2017.03.001.
Sciarra A. et al. (2019) - Geochemical characterization of the Nirano mud volcano, Italy. Appl. Geochem., 102, 77-87,
https://doi.org/10.1016/j.apgeochem.2019.01.006
Mechanotransduction, cellular biophotonic activity, and signaling patterns for tissue regeneration
Full text linkSignaling molecules exhibit mechanical oscillations, entailing precise vibrational directionalities. These steering signatures have profound functional implications and are intimately connected with the onset of molecular electric oscillations and biophoton emission. We discuss biophotonic activity as a form of endogenous photobiomodulation, orchestrating the mechano-sensing/-transduction in signaling players. We focus on exogenous photobiomodulation in the form of pulsed wave modulation of selected light wavelengths to direct endogenous biophotonic activity and molecular cellular dynamics. We highlight the relevance of this strategy to target and reprogram the developmental potential of tissue-resident stem cells in damaged tissues, affording precision regenerative medicine without the need for cell or tissue transplantation
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