1,720,957 research outputs found
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
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
Revived interest in dismissed historical Cu-Fe-Zn deposits in the Northern Apennine ophiolites (Italy)
No full textThe increasing need of Critical Raw Materials (CRMs) stable supply has led many European countries
to focus their attention on the metal recovery from dismissed mines, mine wastes, and landfills in
the circular economy spirit. Northern Italy is characterised by more than 100 abandoned mining
sites. Among them, in the Emilia Romagna Region, the Boccasuolo Ophiolite is receiving interest
because the numerous disseminated dismissed historical extractive sites of Volcanogenic Massive
Sulphide (VMS) deposits with a Cyprus-type metallogenic signature (Cu-Fe-Zn) [1]. These deposits
occur as pods within small bodies of ophiolitic basalts cropping out as olistoliths in the Northern
Apennine External Ligurian units. These ophiolites represent remnants of the Jurassic Alpine Tethys,
which formed in an ocean-continent transition zone [2]. They are indeed characterised by sequences
of pillow lavas associated with serpentinite and gabbro breccias, radiolarian cherts, limestones, and
abundant serpentinised subcontinental mantle peridotites. Basalts show OCTZ chemical features
with transitional-MORB affinity and a garnet signature (Dyn/Ybn=1.2-1.4). Boccasuolo Ophiolite’s
VMS deposits were formed by circulation of metal-rich hydrothermal fluids which, mixed with
heated seawater through a network of fissures, developed quartz-sulphide veins [3]. To better
constrain the CRMs potential of these VMS deposits, we performed bulk rock geochemical analyses
for major and trace elements, and S and C elemental content and relative stable isotopic ratio.
Preliminary results reveal that basalts with mineralisation are enriched in Cu (200 times CC), Zn (118
times CC), and Ag (12 times CC) [4]. Such analyses are crucial to reconstruct the ore-formation
processes and trace metal enrichment of the main rocks, which led to the formation of Cu-Fe-Znbearing
sulphide deposits associated with basaltic rocks.
References:
[1] Garuti G. et al., (2011) Lithos 124 243-254 https://doi.org/10.1016/j.lithos.2010.11.006
[2] Kiss G. et al., (2023) Minerals 13 8 https://doi.org/10.3390/min13010008
[3] Saccani, E. (2015) Geosci. Frontiers https://doi.org/10.1016/j.gsf.2014.03.006
[4] Rudnick, R.L., Gao, S. (2014) Treatise on Geochemistry https://doi.org/10.1016/B978-0-08-095975-
7.0.00301-
Potential mineral resources in historically dismissed volcanogenic massive sulfide (VMS) deposits of the Emilia Romagna region (Italy): petrological and geochemical study for Critical Raw Materials (CRMs) exploration and exploitation
No full textThe last update on the Critical Raw Materials Act (2023) drawn up by the European Union identified
54 Critical Raw Materials (CRMs), i.e., minerals, elements, or materials that are fundamental to supply for
technology and strategic for the green transition, but subjected to fickle supply, e.g., for the fragile geopolitical
contest (Kiss et al., 2023). This led many European countries, including Italy, to focus on the metal recovery
from dismissed mines, mine wastes, and landfills to accomplish the circular economy politics. Italy has
more than 100 historically dismissed mining sites just in the North, and, among them, the ones in the Emilia
Romagna region are now under investigation for the various volcanogenic massive sulfide (VMS) deposits
(Zaccarini & Garuti, 2008). These are a type of metal sulfide ore deposits that occur as a result of underwater
volcanic eruptions, associated with hydrothermal events in submarine environments, and are divided based
on ore composition (Cu, Cu-Zn, Cu-Zn-Pb group) and environment formation (Cyprus, Kuroko, Besshi, as
mentioned by Zaccarini & Garuti, 2008). In the Emilia Romagna region, these deposits occur as pods within
small bodies of ophiolitic basalts cropping out as olistoliths in the Northern Apennine External Ligurian units
and owe their origin to the metal-rich hydrothermal circulation which developed quartz-sulfide veins when
mixed with seawater through a fissures network (Saccani, 2015; Kiss et al., 2023). These ophiolites represent
Jurassic Alpine Tethys oceanic crust fragments obducted in the continental crust (Zaccarini & Garuti, 2008).
The stratigraphy of the area is characterized by sequences of pillow lavas associated with serpentine and gabbro
breccias, radiolarian cherts, limestones, and abundant serpentinized subcontinental mantle peridotites (Kiss et
al., 2023). Basalts, then, show Ocean Continent Transition Zone (OCTZ) chemical features with transitionalMORB affinity and a garnet signature (Dyn/Yb0: 1.2-1.4, Saccani, 2015), in agreement with Cyprus-type
VMS deposits (Zaccarini & Garuti, 2008). Major and trace elements bulk rock geochemical analyses were
performed in a group of basalts of the Boccassuolo ophiolite and compared with the previous results (e.g.,
Barrie & Hannington, 1999; Zaccarini & Garuti, 2008; Kiss et al., 2023): the VMS deposits in the Emilia
Romagna region belong to the Cu and Cu-Zn types (Cu up to 5818 ppm, 200 times Upper Continental Crust,
UCC, composition; Zn up to 7941 ppm, 118*UCC), low to very low Pb contents (< 1 ppm, max. 0.42*UCC).
These preliminary results provide the first relevant geochemical information to map trace metal enrichment
distribution in the main rocks of the area. Radiogenic (Sr-Nd-Pb) and stable (S-C) isotopic analyses, as well as
mineralogical and in-situ analyses, will provide additional information on the enrichment and distribution of
VMS deposits in the Region.
Barrie C.T. & Hannington M.D. (1999) - Classification of Volcanic-Associated Massive Sulfide Deposits Based on
Host-Rock Composition. In: Barrie C.T. & Hannington M.D. (Eds), Volcanic-Associated Massive Sulfide Deposits:
Processes and Examples in Modern and Ancient Settings, Rev. Econ. Geol., 8, 2-10.
Kiss G.B. et al. (2023) - Tracing the Source of Hydrothermal Fluid in Ophiolite-Related Volcanogenic Massive Sulfide
Deposits: A Case Study from the Italian Northern Apennines. Minerals, 13, 8.
Saccani E. (2015) - A new method of discriminating different types of post-Archean ophiolitic basalts and their
tectonic significance using Th-Nb and Ce-Dy-Yb systematics. Geosci. Front., 6, 481-501, https://doi.org/10.1016/j.
gsf.2014.03.006.
Zaccarini F. & Garuti G. (2008) - Mineralogy and chemical composition of VMS deposits. Mineral. Petrol., 94, 61-83,
https://doi.org/10.1007/s00710-008-0010-9
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
Geochemical characteristics of a newly discovered Vigarano chondrite fragment (CV3) – Study of redox conditions with unconventional Mössbauer spectroscopy
No full textThe Vigarano meteorite fell in 1910 in the province of Ferrara, Italy, and, after the impact, was divided
into two blocks, “Cariani” and “Morandi”, respectively, named after the owners of the farms where they were
recovered (Trevisani, 2011 and reference therein). A new series of debris was found in a storehouse near the
impact site at the beginning of the XXI century and was classified as part of the Cariani stone (Trevisani, 2011).
This meteorite has been widely studied and represents the reference type of the reduced CV3 carbonaceous
chondrite group (McSween, 1977). Notwithstanding it is worth noticing that the main contribution to the
nature and origin of this meteorite is from fragments of the Morandi block, while knowledge on the other block
is scarce.
This work aimed to characterize one of these newly discovered fragments to confirm its belonging to the
Vigarano meteorite, with both bulk (XRF, and ICP-MS), in-situ (EMPA) major and trace element contents,
and C-S elemental and isotopic (EA-IRMS) analyses. EMPA and petrographic thin section analyses did not
identify phyllosilicates and carbonates, which were determined in the literature dealing with the Morandi block
(McSween, 1977). Therefore, additional Mössbauer spectroscopy analyses were conducted to investigate iron
speciation and possibly to determine the formation system’s redox conditions and volatile elements circulation
in the planetary body. Both XRF and ICP-MS analyses showed a composition in agreement with the literature
data (McSween, 1977; Dauphas & Pourmand, 2015), confirming at first, that the recovered unnamed meteorite
fragments belonged to the Vigarano meteorite, even though the fragment had no CAIs evidence, and, for major
elements, a higher Mg/Si (1.43 versus 0.94) and Fe/Si (1.59 versus 1.46) and lower Ca/Al rate (0.71 versus
1.09). Slightly differences between the two blocks were also observed for trace element contents: the newly
found fragment had a lower Eu (0.09 versus 0.11 ppm), Gd (0.29 versus 0.40 ppm), Dy (0.40 versus 0.53 ppm),
Er (0.25 versus 0.30 ppm), Lu (0.04 versus 0.05 ppm) contents than what found in the well-studied Morandi
block (Dauphas & Pourmand, 2015).
Due to a lack of carbonates and less sulfides presence, carbon and sulfur elemental contents (0.92±0.05,
1.38±0.05 wt.%) and isotopic ratios (δ13CPDB: -17.8 PDB, δ34SCDT: +0.3 CDT) were lower compared with
literature CV3 values (e.g., McSween, 1977).
The iron speciation determined with Mössbauer analyses led to an Iron Oxidation Index (IOI), whose
results increase with increasing oxidized iron to the total iron content, with a value of 2.13, consistent with
the 2.12 shown in the classification of reduced CV3 group (Garenne et al., 2019). The sample contained 17%
Fe3+
, attributable to incipient thermal metamorphism that tends to form magnetite and oxidize Fe in silicates
and matrices. The fragment is more oxidized when comparing the IOI with the literature value (Garenne et al.,
2019).
Dauphas N. & Pourmand A. (2015) - Thulium anomalies and rare earth element patterns in meteorites and Earth:
Nebular fractionation and the nugget effect. Geochim. Cosmochim. Ac., 163, 234-261, https://doi.org/10.1016/j.
gca.2015.03.037.
Garenne A. et al. (2019) - The iron record of asteroidal processes in carbonaceous chondrites. Meteorit. Planet. Sci., 54,
2652-2665, https://doi.org/10.1111/maps.13377.
McSween H.Y. JR. (1977) - Petrographic variations among carbonaceous chondrites of the Vigarano type. Geochim.
Cosmochim. Ac., 41, 1777-1790, https://doi.org/10.1016/0016-7037(77)90210-1.
Trevisani E. (2011) - History of the Vigarano meteorite (Emilia-Romagna, Italy) and recovery of an important part of their
mass. Rend. Lincei Sci. Fis., 22, 315-326, https://doi.org/10.1007//s12210-011-0137-1
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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