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The submerged structure and stratal architecture of the Neapolitan Yellow Tuff (NYT) caldera, offshore the Campi Flegrei, (Eastern Tyrrhenian Margin): new insights from high resolution seismics and gravity core data
Full text linkThe Campi Flegrei is an active volcanic area defined by a
quasi-circular depression that covers some 200 km2 of the coastal
zone of SW Italy, a large part of which develops off the Naples
(Pozzuoli) Bay (Fig. 1). The area has been active at least since 60
ka BP ( Pappalardo et al., 1999), and is structurally dominated by a
caldera, 6 km in diameter, associated with the eruption of the
Neapolitan Yellow Tuff (NYT), a 40 km3 Dense Rock Equivalent
(DRE) ignimbrite (Scarpati et al., 1993) dated at ca 15 ka BP
(Deino et al., 2004), that covered the district now occupied by the
city of Naples, the Campi Flegrei and a large area of the
continental shelf off the Pozzuoli Bay.
The volcanological evolution of the NYT caldera as been long
described on the basis of outcrop and subsurface studies onland
(Rosi & Sbrana, 1987; Orsi et al., 1996, 2004 and references
therein; Di Vito et al., 1999; Perrotta et al., 2006; Fedele et al.,
2011), but its offshore morphology, detailed structure and recent
stratigraphic setting are still poorly understood.
In this study we integrate geological and geophysical data of
different resolution/penetration obtained from high-resolution
reflection seismic profiles (Sparker and Chirp source) with gravity
core and swath bathymetry to better constrain the shallow
structure, stratigraphic architecture and latest Quaternary to
Holocene evolution of the submerged sector of the NYT caldera
off the Pozzuoli Bay.
Our data clearly image, for the first time, the offshore geometry
of the NYT caldera ring-fault zone, as well as the style and timing
of volcano-tectonic deformation associated with the late stage
evolution of the NYT inner caldera resurgence. Our interpretation
suggests that since 15 ka the offshore sector of NYT inner caldera
underwent significant deformation and uplift (with minor
subsidence episodes) that occurred at almost the same rate as the
post-glacial sea-level rise. Particularly, the inner Pozzuoli Bay
started to deform soon after 15 ka BP, when sea-level rise was
initially faster than uplift. This caused a general increase of the
accommodation space that was progressively filled up by
volcaniclastic sediments. Since ca. 8 ka BP, along with the mid
Holocene decrease in the rate of the sea-level rise, the early NYT
resurgent structure was then uplifted up to the sea-level or even to
partial subaerial exposure. From ca. 8 to 5 ka BP two distinct
layers of volcaniclastic resediments, mostly represented by gravity
flow deposits, formed throughout the Bay. A significant post-
Roman (post 2 ka BP) subsidence phase of ca 10 m is then
recorded offshore Pozzuoli by the drowning of the infralittoral
prograding wedge below the present-day fair-weather wave base.
REFERENCES
Deino AL, Orsi G, de Vita S, Piochi M (2004) The age of the Neapolitan Yellow
Tuff caldera-forming eruption (Campi Flegrei caldera—Italy) assessed by
40Ar/39Ar dating method. J. Volcanol. Geotherm. Res. 133, 157–170.
Di Vito M., Isaia R., Orsi G., Southon J., de Vita S., D’Antonio M., Pappalardo
L., Piochi M., 1999. Volcanism and deformation since 12,000 years at the
Campi Flegrei caldera (Italy), J. Volcanol. Geotherm. Res. 91 (2-4), 221-246.
Fedele L., Insinga D.D., Calvert A.T., Morra V., Perrotta A., Scarpati C., 2011.
40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy):
toward a new chronostratigraphic reconstruction of the Holocene volcanic
activity. Bull. Volcanol. 73, 1323-1336.
Orsi G, de Vita S, Di Vito M, 1996. The restless, resurgent Campi Flegrei nested
caldera (Italy): constraints on its evolution and configuration. J. Volcanol.
Geotherm. Res. 74, 179–214.
Orsi G., Di Vito M.A. Isaia R., 2004. Volcanic hazard assessment at the restless
Campi Flegrei caldera. Bull. Volcanol. 66, 514–530.
Pappalardo L., Civetta L., D’Antonio M., Deino A., Di Vito M., Orsi G.,
Carandente A., de Vita S., Isaia R. & Piochi M., 1999. Chemical and Srisotopical
evolution of the Phlegrean magmatic system before the Campanian
Ignimbrite and the Neapolitan Yellow Tuff eruptions J. Volcanol. Geotherm.
Res. 91, 141-166.
Perrotta A., Scarpati C., Luongo G., Morra V., 2006. The Campi Flegrei caldera
boundary in the city of Naples. In: De Vivo B (ed) Volcanism in the
Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites. Elsevier,
Amsterdam, pp 85–96 (in the series Developments in Volcanology, 9)
Scarpati C., Cole P., & Perrotta A., 1993. The Neapolitan Yellow Tuff- A large
volume multiphase eruption from Campi Flegrei, Southern Italy. Bull.
Volcan. 55, 343-35
The Late-Holocene and recent evolution of Lago Patria (a coastal lagoon in southern Italy) from subsurface data and historical cartography
No full textArchitettura stratigrafica ed evoluzione del Golfo di Pozzuoli negli ultimi 15 ka:una nuova prospettiva sulla caldera del Tufo Giallo Napoletano,Campi Flegrei, margine tirrenico orientale.
Full text linkI Campi Flegrei rappresentano un distretto vulcanico attivo che si sviluppa al confine tra il settore emerso
e sommerso del margine continentale campano. Il distretto vulcanico occupa una superficie di circa 200 km2,
è strutturalmente dominato da una caldera di collasso del diametro di circa 8 km formatasi in seguito
all’eruzione del Tufo Giallo Napoletano (TGN), un deposito ignimbritico del volume di 30-50 km3 Dense
Rock Equivalent, datato a 15 ka B.P. circa, ed è attivo da almeno 78 ka B.P circa.
L’obiettivo di questo lavoro è di ricostruire l’architettura stratigrafica e l’evoluzione vulcanotettonica
tardo-Quaternaria del sistema caldera di collasso - faglia anulare - risorgenza intra-calderica del settore
sommerso della caldera del TGN. A tal fine è stata analizzata una fitta maglia di profili sismici a riflessione
monocanale di alta (Sparker) ed altissima (Subbottom Chirp) risoluzione. I dati sismici sono stati
successivamente integrati sia con quelli ottenuti dall’analisi di carotaggi a gravità e batimetrici multibeam
che con quelli disponibili in letteratura e, nell’insieme, analizzati in ambiente GIS.
I nuovi dati indicano che il settore interno dell’area collassata a seguito dell’eruzione del TGN evolve
inizialmente in condizioni di mare basso. L’area intra-calderica viene successivamente interessata dalla
formazione di una struttura antiforme (risorgenza intra-calderica) il cui tasso di sollevamento è stato
comparabile con l’innalzamento eustatico nell’intervallo Pleistocene superiore – Olocene [Lambeck et al.,
2011]. A circa 10 ka B.P. il settore centrale della struttura risorgente raggiunge l’esposizione subaerea
(terrazzo morfologico de “La Starza”).
La calibrazione dei profili sismici Chirp con markers tefro-stratigrafici riconosciuti in un carotaggio e
datati al 1538 A.D., 79 A.D. indica l’instaurarsi di un periodo di subsidenza in epoca post-Romana, registrato
dall’annegamento di 10-25 m del cuneo di progradazione infralittorale rispetto alle profondità di equilibrio
funzionale attualmente segnalate in area Mediterranea. L’interpretazione sismostratigrafica rivela, inoltre, la
presenza di fluidi che risalgono attraverso la zona di faglia anulare che delimita la caldera del TGN.
Bibliografia
Lambeck, K., Antonioli, F., Anzidei, M., Ferranti, L., Leoni, G., Scicchitano, G., Silenzi, S., (2011). Sea
level change along the Italian coast during the holocene and projections for the future. Quaternary
International, 232, 250-257
Radiocarbon dating versus volcanic event stratigraphy: Age modelling of Quaternary marine sequences in the coastal region of the Eastern Tyrrhenian Sea
No full textWe present the results of an integrated stratigraphic study conducted on eight marine sediment cores collected in the Naples and Salerno Bays, Eastern Tyrrhenian Sea. The aim of the study is the understanding of the timing and the impacts on the sedimentary environment of explosive volcanic events that occurred over the coastal zone of the Campania region during the latest Quaternary. Accurate dating and correlation have been essential for the construction of reliable models of the sediment architecture and influx rates in this area, as well as for establishing the links between changes in sedimentation and palaeoenvironmental events. While in case of deep marine sequences distal ash layers usually offer a significant potential for accurate geochronology, in the case of shallow marine sequences (continental shelf to upper slope) radiocarbon dating revealed to be essential in order to refine correlation among clusters of marine tephra layers with the equivalent proximal pyroclastic deposit onland, particularly where depositional rates are high and the chemistry and age of tephra layers display little variability. The integrated use of AMS 14C dating on marine materials and the tephrostratigraphic approach based on reconstructions of historical volcanic events is fundamental in order to minimize the uncertainties that affect chronologic constraints derived from radiocarbon-based age models. © 2009 Elsevier B.V. All rights reserved
The proximal marine record of Somma-Vesuvius volcanic activity in the Naples and Salerno bays, Eastern Tyrrhenian Sea, during the last 3 kys.
No full textThe tephrostratigraphic analysis of nine gravity cores acquired on the continental shelf of the Naples and Salerno bays documents the proximal record of Somma-Vesuvius volcanic activity during the latest Holocene (last 3 kyrs). Five tephra layers from southern Naples Bay and three tephra layers from northern Salerno Bay were recognised in cores and their sedimentologic structures, textural parameters, stratigraphy and major and trace-element composition described. Proximal products of the well known 79 A.D. eruption along with those of the interplinian activity at 2.7 ka B.P., were identified both in the southern Naples Bay and in the northern Salerno Bay. They represent excellent marker horizons interbedded within the Late Holocene marine record. In addition, several radiocarbon datings provided age constraints on a number of tephras overlaying the 79 A.D. deposits and allowed a detailed stratigraphic reconstruction of medieval (1137 A.D.-685 A.D.) and more recent eruptions as recorded for the first time at sea. These results integrate previous research carried out on subaerial deposits providing new insights on the dispersion, deposition and grain-size distributions, along the northern Campania coastal zone, of recent Somma-Vesuvius products, some of which are still poorly known. The tephrostratigraphic approach to the study of marine sequences of proximal and adjacent areas can thus provide a more detailed description of physical characteristics of pyroclastic deposits, necessary for the correct assessment of volcanic hazard in the area. © 2007 Elsevier B.V. All rights reserved
The Neapolitan Yellow Tuff caldera offshore the Campi Flegrei: Stratal architecture and kinematic reconstruction during the last 15 ky
Full text linkIn this study we integrate high-resolution swath bathymetry, single channel reflection seismic data and gravity
core data, to provide new insights into the shallow structure and latest Quaternary to Holocene evolution of
the submerged sector of the Neapolitan Yellow Tuff (NYT) caldera (Campi Flegrei) in the Pozzuoli Bay. The
new data allow for a reconstruction of the offshore geometry of the NYT caldera collapse–ring fault system,
along with the style and timing of deformation of the inner caldera resurgence.
Our interpretation shows that the NYT eruption (~15 ka BP) was associated with a caldera collapse bounded by
an inward-dipping ring fault system. The ring fault system consists in a 1–2 km wide fault zone that encircles an
inner caldera region ~5 km in diameter and is often marked by the occurrence of pore fluids ascending through
the fault zone, up to the seafloor, particularly in the western sector of the bay. A shallow magmatic intrusion
along the ring fault zone was also detected offshore Bagnoli in the eastern part of the Pozzuoli Bay.
Following the NYT eruption, the inner caldera region underwent significant deformation and resurgence with a
maximum cumulative uplift of the offshore structure in the order of 180 m. The net uplift rate of the caldera
resurgent dome was ~9–12 mm/year during the period 15.0–6.6 ka BP. The style of deformation of the resurgent
structure can be described in terms of a broad doming, accompanied by subordinate brittle deformation, mostly
concentrated in a small apical graben at the summit of the resurgent dome.
Chronostratigraphic calibration of seismic profiles obtained by three tephra layers cored in the Pozzuoli Bay indicates
5 to 25 m of post-Roman differential subsidence and tilting towards ESE of the inner caldera resurgence,
as recorded by the drowning of the infralittoral prograding wedge below the present-day storm wave base
Insights into the Holocene evolution of the Volturno river delta system, Eastern Tyrrhenian Margin
Full text link
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
A high-resolution record of landscape changes and land use over the last 5000 years in western Calabria (S. Eufemia Gulf, southern Tyrrhenian Sea, Italy)
No full textPollen analysis of a marine core collected in the Gulf of S. Eufemia (Tyrrhenian Calabria, Italy) allowed reconstructing the regional changes in vegetation and land use over the last 5000 years. Pollen diagram zonation through Constrained Cluster Analysis highlighted three compositional zones whose boundaries mark the major changes that affected the vegetation structure. A dense forest cover with a few signs of human activities characterized the wide pollen source area from 5055 to 2700 BP (Zone 1). In this period, the Pre-Protohistoric communities were mainly concentrated on the Tropea Promontory where they had a significant local impact. Minor forest rarefactions at 5000–4800 BP, ca. 4400–4000 BP, ca. 3450–3150 BP were correlated to phases of climatic shifts toward aridity. From 2700 to 2000 BP (Zone 2a), a longer and more incisive period of forest decline was connected to a time of aridity that favored the intense activities of an increasing anthropogenic pressure. Indeed, important urban centers developed in the area during the Greek and Roman colonization. Diffuse deforestation and cultivation occurred from 790 BP (Zone 3), enhancing soil erosion and fluvial discharge as testified by the sudden increase in sedimentation rates. This disruption of the slope morphodynamics was connected to the collapse of territorial management following the end of the Western Roman Empire. Compositional Data Analysis, applied to a simplified pollen dataset, highlighted both a negative correlation between Abies and Fagus and a close similarity between the AP/NAP curve and the Axis 1 scores of the Relative Variation Biplot
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