1,721,027 research outputs found
A new Arctic seepage site? Preliminary evidence from benthic community.
Full text linkThe Kveithola Trough is an abrupt and narrow sedimentary system located in the NW Barents Sea. The hydrographic,
bio-geochemical conditions and the possible existence of gas seepage activity of the area have been
investigated during the Eurofleets 2- BURSTER cruise, conducted on board the German icebreaker RV Polarstern.
The aim of our work is to characterize the benthic biota and more specifically the macrofaunal community
structure coupled to the study of benthic foraminiferal meiofauna.
Preliminary qualitative results revealed that in the inner Kveithola Trough, the macrofaunal community is
composed by abundant black worm tubes (Chaetopteridae worms and Siboglinidae-like taxa) with presence of
Thyasiridae bivalve species. The occurrence of these macrofaunal taxa is usually associated to oxygen-reduced
environments, hydrothermal vents and cold seeps. The living benthic foraminiferal assemblage in the same
stations is characterized by the presence of typically oxygen-depleted environmental taxa including the calcareous
species Nonionellina labradorica and Globobulimina spp.. Conversely, in the outer Kveithola trough, both benthic
macrofauna and foraminiferal meiofauna assemblages are characterized by less opportunistic taxa with a higher
biodiversity suggesting very distinct oceanographic sea bottom conditions.
The organic matter richness plays a large role in the Kveithola Trough environmental setting and may bring
anoxic conditions that could affect the biota of the area. In fact, the benthic community structure of this area
inhabits suboxic, anoxic and organic-enriched sediments and disturbed environments, forming assemblages with
low diversity and high abundances of a few tolerant and/or specialized species.
This preliminary finding could be consistent with other studies examining benthic community structure around
Svalbard and in particular cold seep and vents habitats where faunal characteristics are patchy, suggesting
small-scale heterogeneity in the environment surrounding cold seeps. For said reasons we envisage the presence
of a new Arctic seepage site having a strong local impact on the benthic system
Late Quaternary palaeoceanography and sea-ice history in the Kveithola Trough Mouth Fan (NW Barents Sea)
No full textThe north-western continental margin of the Barents Sea represents an important gateway for the influx
of the relative warm and saline Atlantic Water (AW) towards the Arctic Ocean. The AW influx into the Arctic
Ocean varied considerably over the late Quaternary playing an important role on the climatic conditions of the
Arctic (i.e. Werner et al., 2013). The western Barents Sea represents a key area to study the palaeoceanographic
conditions, which occurred during the past. We present the high resolution (centennial scale) foraminiferal
study of two cores collected from the Storfjorden-Kveithola depositional system (NW Barents Sea) during the
EGLACOM and CORIBAR projects. The aim is to reconstruct the paleoceanographic and paleoenvironmental
evolution after the Last Glacial Maximum, using expanded sedimentary sequences (over 6 m thick Holocene
record in the core collected on the Kveithola Trough Mouth Fan, Carbonara et al., 2018; Caricchi et al., 2018).
The chronological framework defined by the paleomagnetism (Charicchi et al., 2018), evidences that the
ecobioevents highlighted by the planktic microfauna occurred more or less synchronously throughout the
studied area. The high diversity of the assemblage reveals an early Holocene Climatic Optimum terminating
with the 8.2 Ka cold spell, characterised by a low diversity assemblage dominated by the high primary
productivity indicator, Turborotalita quinqueloba.
The benthic foraminiferal assemblage indicates deglaciation conditions before the Holocene. In the
glaciomarine sediments, the benthic assemblage mainly contains Cassidulina reniforme, C. neoteretis,
Islandiella helenae/norcrossi and Cibicides lobatulus. The significant occurrence of very small taxa (> 63
μm), such as Stetsonia horvathi and Seabrookia earlandi, suggests conditions of low productivity related to
permanent sea ice conditions during the medium-late Holocene. In the late Holocene, the increasing occurrence
of Epistominella arctica, E. exigua and Eilohedra nipponica, phytodetritus feeders, records mostly seasonal
sea ice conditions
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
Sedimentary processes and glacial cycles on the sediment drifts of the Antarctic Peninsula pacific margin: preliminary results of SEDANO-II Project.
No full textMud volcanoes along the inner deformation front of the Calabrian Arc accretionary wedge (Ionian Sea)
No full textWe present geophysical data integrated with the analysis of well-targeted sediment samples in order to contribute to a better understanding of fluid circulation in the Calabrian Arc accretionary wedge. Two cores (BS81/II 5 and BS81/II 10) collected on a swell in the hangingwall of the inner deformation front show upper Pleistocene mud breccias that include Cretaceous to Late Miocene rock fragments mechanically incorporated into the eruption deposit by the upward transport of overpressured fluids. An additional core (CALA 21) came from the summit of a topographic high in the footwall of the inner deformation front of the accretionary wedge and contains a mud breccia patchy/cloudy facies where sediment disturbance is caused by fluid expulsion. Integration of the entire data set provides evidences of the interplay among tectonics, fluid emissions and sedimentation, and enables the identification of two new volcanoes in the accretionary prism where overpressuring due to Pliocene and Pleistocene sediment accumulation and the evolution of active fault systems triggered fluid circulation and the formation of those structures
Paleoceanographic changes suggested by planktic and benthic foraminifera in the Western Svalbard Slope (Bellsund Drift) during the last century.
No full textThe objective of this study is to reconstruct the last century’s climatic oscillations in the Western Svalbard Slope (Arctic region) using high-resolution analysis of planktic and benthic foraminiferal assemblages as proxies for surface and deep-water mass properties. In the studied area, warm Atlantic water masses are
advected to the Arctic Ocean through the West Spitsbergen Current, representing the northernmost tip of the Global Thermohaline Circulation. The interaction between the cold Arctic and the warm Atlantic water masses significantly influences the entire foraminiferal community. The paleoenvironmental reconstruction obtained with the microfossil assemblages, together with data from satellite monitoring of the sea ice extent and the long-term record of the annual temperature of the West Spitsbergen Current measured over the last 50 years,
support the evidence of a progressively rising heat influx into the Arctic Ocean due to an increasing Atlantic water inflow, forcing the consequent decay of the sea ice extent
Biostratigraphic caracterization and Quaternary microfossil palaeocology in sediment drifts west of the Antarctic Peninsula - implicatons for cyclic glacial-interglacial depositing
No full textLate-Quaternary Meltwater Pulses investigated through sedimentological, micropaleontological and geochemical approach: preliminary results
No full textClimate changes and sea level rise during the next century are two of the main environmental challenges
to face by the modern society. Sea level change responds to a variety of processes including ocean thermal
expansion and ice sheet melting in the polar areas. The latter have been responsible for past abrupt relative
sea level rises known as meltwater pulses that deeply changed the Earth’s physiography after Last Glacial
Maximum by submerging the paleo coastal areas. Meltwater pulses are short-lived global acceleration in sealevel
rise resulting from intense glacial melting, surge of large ice streams into oceans and intense iceberg
discharge during ice sheet disintegration (Blanchon, 2011). The main concerns related to the present fast
global climate changing is the possibility that sudden drastic ice loss from Greenland and/or in the West
Antarctic Ice Sheet would lead to a new abrupt acceleration of the relative sea level rise with consequent
inundation of vast coastal areas and/or to cause an abrupt slowdown of the Atlantic Meridional Overturning
Circulation (i.e. Golledge et al., 2014). To better understand the dynamics and risks associated with the onset
of past meltwater pulses, their impact on thermohaline ocean circulation and climate it is pivotal the geological
study of the well preserved and most recent meltwater pulses events occurred during the Late Quaternary,
particularly those occurred during the Last Glacial Termination. Here, we present some preliminary results of
the sedimentological, micropaleontological and geochemical investigation of 4 sediment cores collected on the
Western margin of the Svalbard archipelago, next to the Fram Strait in the Artic
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
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