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Planktonic foraminifera as proxies of the Holocene climatic variability (Tyrrhenian, Mediterranean Sea)
Full text linkIntroduction. The focus of this study is the paleoclimatic reconstruction of the southern Tyrrhenian
between ~9.2 and 2.9 ka, through the study of planktonic foraminiferal assemblages and stable
isotopes, and comparing data with other coeval intervals. Several authors have studied the climatic
sensitivity of Holocene planktonic foraminifera in different parts of the Mediterranean. Planktonic
foraminifera produce good records of Holocene climatic variability, especially as regards the suborbital
events such as Bond events (Bond et al., 1997) and other cooling/warming oscillations.
Therefore, the obtained eco-biostratigraphy has allowed us to analyze how climatic forcing influenced
sea surface temperature (SST) and water column structure during the Holocene in this sector
of the southern Tyrrhenian Sea.
Methodology. A sedimentary core (196 cm long) was collected in the Gulf of Palermo at the base
of the upper continental slope (990 m bsl) and sub-sampled every 2 cm. Micropaleontological and
geochemical analyses were performed on 98 samples, and three AMS 14C dates were determined.
Micropaleontological analyses consisted of qualitative and quantitative characterization of the
planktonic foraminiferal assemblages, in the size fraction greater than 125 μm. Geochemical analyses
were performed on 8–10 specimens of Globigerina bulloides.
Results. The calibrated AMS 14C ages, together with planktonic foraminiferal fluctuations and G.
bulloides oxygen isotope records, were used to develop an age model of the studied interval. In order
to obtain additional age control points, the studied records were also tuned to the NGRIP δ18O
(GICC05) (Svensson et al., 2008) and GISP2 ice core temperature (Alley, 2000) records.
Twenty species and eco-morphotypes were recognized in the planktonic foraminiferal assemblage
and grouped depending upon their climatic and feeding affinity. The warm-water species, minus
the typical cold-water species, were used to obtain the paleoclimatic curve, whilst the herbivorous/
carnivorous ratio has permitted us to reconstruct the trophism of the southern Tyrrhenian. In
particular, between ~8 and 6.4 ka, an important warming phase was recognized, clearly indicated
by the increase of Globigerinoides gr. ruber and G. gr. quadrilobatus. This interval corresponds to
the deposition of Sapropel S1b-equivalent stage (Sprovieri et al., 2003; Lirer et al., 2013; Siani et
al., 2013), when high SSTs and oligotrophy characterized the entire Mediterranean region, especially
during the summer seasons. Between ~5.9 and 4.2 ka, another warming phase occurred in the
Gulf of Palermo, differing from the previous one due to the enhanced winter mixing of the water
column, testified by the high abundance of deep dweller species, such as Globorotalia truncatulinoides
and Globorotalia inflata left coilings. The last important warming phase corresponds to the
Minoan Warm Period, briefly interrupted by a rapid cooling event (at ~3.5 ka).
Among these warm climatic phases, several rapid cold-cool events were recognized. In particular,
Neogloboquadrina pachyderma and Turborotalita quinqueloba represent the best cold-water indicators,
increasing in abundance during the Bond events (B2, B3, B4, B5, B6) and other rapid cooling
events that characterized the western (M3, M4, M5, M6, M7) (Frigola et al., 2007) and central
Mediterranean (TC2, TC3, TC4) (Cacho et al., 2001) during the 9.2–2.9 ka interval.
Conclusions. Planktonic foraminifera and oxygen isotope variations highlight the climatic oscillations
of the relatively stable Holocene stage. These oscillations are linked to the North Atlantic millennial
scale climatic variability that forced cool/high productivity periods and warm/oligotrophic
conditions. In particular, during the ~8–6.4 (S1b-equivalent), ~5.9–4.2, and ~3.7–3.2 (Minoan
Warm Period) ka intervals, warm surface waters characterized the Gulf of Palermo. On the contrary,
during rapid climatic phases, centered at 9.1, 8.2, 7.2, 6.2–5.9, 5.4, 4.7, 3.9, 3.5, and 3 ka,
cool/high productivity conditions occurred in this sector of the southern Tyrrhenian.
References
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Bond G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., de Menocal, P., Priore, P., Cullen, H.,
Hajdas, I. and Bonani, G., 1997. A pervasive millennial-scale cycle in North Atlantic
Holocene and glacial climates. Science 278: 1257–1266.
Cacho, I., Grimalt, J.O., Canals, M., Sbaffi, L., Shackleton, N.J., Schönfeld, J., and Zahn, R., 2001.
Variability of the Western Mediterranean Sea surface temperature during the last 30,000
years and its connection with the northern hemisphere climatic changes. Paleoceanography
16(1): 40–52.
Frigola, J., Moreno, A., Cacho, I., Canals, M., Sierro, F.J., Flores, J.A., Grimalt, J.O., Hodell, D.A.,
and Curtis, J.H., 2007. Holocene climate variability in the western Mediterranean region
from a deepwater sediment record. Paleoceanography 22(2): PA2209.
Lirer, F., Sprovieri, M., Ferraro, L., Vallefuoco, M., Capotondi, L., Cascella, A., Petrosino, P.,
Insinga, D.D., Pelosi, N., Tamburrino, S., and Lubritto, C., 2013. Integrated stratigraphy
for the late Quaternary in the eastern Tyrrhenian Sea. Quaternary International 292, 71–
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Siani, G., Magny, M., Paterne, M., Debret, M., and Fontugne, M., 2013. Paleohydrology
reconstruction and Holocene climate variability in the South Adriatic Sea. Climate of the
Past 9: 499–515.
Sprovieri, R., Di Stefano, E., Incarbona, A., and Gargano, M.E., 2003. A high-resolution record of
the last deglaciation in the Sicily Channel based on foraminiferal and calcareous
nannofossil quantitative distribution. Palaeogeography, Palaeoclimatology, Palaeoecology
202(1–2): 119–142.
Svensson, A., Andersen, K.K., Bigler, M., Clausen, H.B., Dahl-Jensen, D., Davies, S.M., Johnsen,
S.J., Muscheler, R., Parrenin, F., Rasmussen, S.O., Röthlisberger, R., Seierstad, I.,
Steffensen, J.P., and Vinther, B.M., 2008.
High-resolution 3D model of Plio-Pleistocene stratigraphy succesion in Southwestern Sicily foreland-basin system
No full textThe southwestern Sicily represents a key sector for studying the Late Pliocene-Pleistocene stratigraphic evolution of the Sicilian foreland-basin system. The data collected during the realization of the sheets n.628 “Sciacca” and n.618 “Castelvetrano” (CARG project) revealed important sedimentological, stratigraphic, and tectonic features, enabling the accurate geological reconstruction of two sedimentary basins (Menfi and Ribera basin) set on different sectors of the Sicilian Fold and Thrust Belt (FTB). Both are located in the outer sector of the FTB, but the Menfi succession accumulated on a deformed carbonate substrate constituted by the Saccense Domain, while the Ribera succession covers the deformed substrate constituted by the Gela Thrust wedge.
One of the most innovative aspects of this study is represented by the 3D geological model reconstruction. By integrating data from geological mapping, seismic reflection profiles, well logs, geophysical surveys, geological cross-sections a detailed three-dimensional model was produced, greatly improving the understanding of the sedimentary and structural dynamics of the southwestern Sicily.
In the Menfi basin, the Late Pliocene-Pleistocene succession includes the marnoso-arenacea del Belice formation (Piacenzian-Gelasian), constituted by hemipelagic clayey marls, turbiditic sandy silts, and breccias, transitioning to resedimented arenites and calcarenites. This unit passes upward to the Agrigento formation (Calabrian), consisting of hemipelagic clays and marls with intercalated sands and bio-calcarenites.
In the south-eastern sector, the Ribera basin succession includes the Monte Narbone formation (Middle Piacenzian-Early Calabrian), composed of marls and silty clays alternating with sapropelitic layers. Upward, this latter unit is overlain by the Agrigento formation, here featured by thick bio-calcarenites, with cross-lamination and prograding geometries, alternated with sandy marls and clays.
The 3D geo-structural model of the study area well shows as the Monte San Calogero, a ramp anticline with double vergence and left-lateral transpressive kinematics, acts as a structural high separating these two basins. Data revealed that the Menfi sedimentary basin thickens from west to east, reaching about 1250 meters, while the Ribera basin reaches the thickness of 2200 meters, in the offshore sector.
The realization of 3D geological model and the creation of thickness maps for the Plio-Pleistocene sedimentary sequence provided crucial insights into sedimentary and tectonic processes, significantly enhancing the understanding of the Sicilian FTB evolution
Late 6th – early 4th century BCE western Greek amphorae produced in Selinunte (western Sicily): Ceramic paste characterisation by an integrated archaeometric approach
Full text linkThis paper aims at an interdisciplinary, archaeological and archaeometric characterisation of the western Greek amphorae series produced in late Archaic and Classical-period at Selinunte (southwestern Sicily). Furthermore, it seeks for archaeometric parameters useful for its distinction from the morphologically very similar production of nearby Agrigento. The research is based on a macroscopic examination, according to the standardised methods of Fabrics of the Central Mediterranean (FACEM), combined with petrographic analyses of 25 amphorae samples and eight coarse ware samples of presumed local fabric found mostly in Selinunte, in the artisanal quarter, in the western town, and in the major sanctuary on the acropolis. Furthermore, a small selection of three amphorae has been unearthed in the western necropolis of Himera and at Cossyra/Pantelleria. Chemical analyses have been undertaken on a group of ten amphorae and four coarse ware samples. As a result, our study confirms the local manufacture of the entire selection of 33 samples and the more than acceptable petrographic and chemical homogeneity of the ceramic pastes produced with locally sourced clays. Some slight but significant compositional, textural and micro-paleontological differences between Selinuntine and Agrigento productions were pointed out. The identification of a production of western Greek wine-carrying (?) amphorae in Selinunte dating from the late 6th-earlier 4th century BCE supports earlier archaeometric analyses and breaks ground for a better understanding of the colony's economic development during the late Archaic and Classical periods. The present research will help to clarify the distribution of the class especially in Selinunte's territory, while its supra-regional circulation seems to have been quite limited
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
Geophysical Constraints to Reconstructing the Geometry of a Shallow Groundwater Body in Caronia (Sicily)
Full text linkThe characterization of a groundwater body involves the construction of a conceptual model that constitutes the base knowledge for monitoring programs, hydrogeological risk assessment, and correct management of water resources. In particular, a detailed geological and geophysical approach was applied to define the alluvial Caronia Groundwater Body (CGWB) and to reconstruct a hydrogeological flow model. The analysis of the CGWB, located in north-eastern Sicily, was initially approached through a reanalysis of previous stratigraphic (boreholes) and geophysical (vertical electrical soundings and seismic refraction profiles) data, subsequently integrated by new seismic acquisitions, such as Multichannel Analysis of Surface Waves (MASW) and horizontal-to-vertical seismic ratio (HVSR). The analysis and reinterpretation of geoelectrical data allowed the construction of a preliminary 3D resistivity model. This initial modeling was subsequently integrated by a geophysical data campaign in order to define the depth of the bottom of the shallow CGWB and the thickness of alluvial deposits. Finally, a preliminary mathematical model flow was generated in order to reconstruct the dynamics of underground water. The results show that integration of multidisciplinary data represent an indispensable tool for the characterization of complex physical systems
Geophysical Contribution to the Reconstruction of the Hydrological Model of “Barcellona-Milazzo Plain” Groundwater Body, Northen Sicily
No full textThe “Barcellona-Milazzo plain” groundwater body in the northen Sicily, was analysed in detail, through numerous
geophysical measurements that were integrated with stratigraphic data in order to reconstruct the hydrological
model.
The “Barcellona-Milazzo plain” (BMP) groundwater body has been identified within the coastal sector between the
village of Oliveri, to the west, and Capo Rasocolmo, to the east. It also includes several rivers that rise further south
in correspondence with the Peloritani ridge and flow into the wide Barcellona-Milazzo alluvial plain.
On the basis of several geophysical and geological data analysis and interpretation have been used to reconstruct the composition and thickness of the marine and alluvial deposits to construct the conceptual model of groundwater circulation in the Barcellon-Milazzo plain.
For the reconstruction of the subsurface model of the water body, 466 vertical electric surveys and 72 refraction seismic sections acquired in the 70s and 80s (CASMEZ surveys reports) have been reprocessed and reinterpreted. These data have been integrated with 50 HVSR surveys and 85 geognostic boreholes. These data have been integrated with 85 stratigraphic boreholes to obtain the floods in contact with the clayey substrate has been reconstructed, which delimits in depth the groundwater body to calculate the hydrological model
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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