On the occurrence of the Neapolitan Yellow Tuff tephra in the Northern Phlegraean Fields offshore (Eastern Tyrrhenian margin; Italy)

A main volcanic marker has been identified for the first time on the continental shelf of the northern Phlegraean Fields in the Gaeta Gulf (Campania region, eastern Tyrrhenian margin, Italy) by means of Subbottom Chirp profile grid and stratigraphic analysis of a core collected on the slope. In the seismic sections, the core bottom corresponds to the top of a continuous and parallel reflector (V) interbedded within the transgressive deposits of the Late Quaternary-Holocene depositional sequence. The Transgressive System Tract deposits are particularly thick compared to the majority of the transgressive deposits of other shelf settings. This might be due to the input of pyroclastic and volcanoclastic deposits related to the intense eruptive activity of the Campania Plain during the Late Pleistocene-Holocene time span. Undulations and pockmarks are the main morphological features of the sea floor and they might be linked to gas uprising, widely detected in the study area. The V reflector is located on the shelf from northeast to southwest at different depths, ranging from 10 ms (about 8 m) to 30 ms (about 25 m) below sea floor and it can be mapped down to the continental slope. The geological calibration of this continuous reflector coupled with tephrostratigraphic analysis, allowed to correlate it with the Neapolitan Yellow Tuff deposits emplaced at Phlegraean Fields at ca. 15 ka

Climate fluctuations and human impact during the late Holocene in a multi-proxy marine record from the Gulf of Gaeta (Tyrrhenian Sea, central Italy)

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Open-slope, translational submarine landslide in a tectonically active volcanic continental margin (Licosa submarine landslide, southern Tyrrhenian Sea)

The southern Tyrrhenian continental margin is the product of Pliocene-Recent back-arc extension. An area of approximately 30 km of gentle (about 1.5°) lower slope of the last glacial outer shelf sedimentary wedge in water depths of between 200 and 300 m failed between 14 and 11 ka BP. We approached the landslide by multibeam and sub-bottom profiler surveying, high-resolution multichannel seismics, and coring for stratigraphic and geotechnical purposes. With regard to a slope-stability analysis, we carried out an assessment of the stratigraphic and structural setting of the area of the Licosa landslide. This analysis revealed that the landslide detached along a marker bed that was composed of the tephra layer Y-5 (c. 39 ka). Several previously unknown geological characteristics of the area are likely to have affected the slope stability. These are the basal erosion of the slope in the Licosa Channel, a high sedimentation rate in the sedimentary wedge, earthquake shaking, the volcanic ash nature of the detachment surface, subsurface gas/fluid migration, and lateral porewater flow from the depocentre of wedge to the base of the slope along the high-permeability ash layers. A newly discovered prominent structural discontinuity is identified as the fault whose activity may have triggered the landslide

Tephrochronology in faulted Middle Pleistocene tephra layer in the Val dAgri area (Southern Italy)

The High Agri River Valley is a Quaternary Basin located along the hinge of the Southern Apennines fold-andthrust belt. The inner margin of the orogen has been affected by intense transtensional and normal faulting, which accompanied vigorous volcanism during the Quaternary. Marker tephra layers are distributed across the whole of Southern Italy and provide a powerful tool to constrain both the size of eruptions and the regional activity of extensional faults controlling basin evolution. Paleoseismological trenching within the Monti della Maddalena range, that borders the Agri River Valley to the south-west, has exposed a faulted stratigraphic sequence and recovered a 10 cm thick tephra layer involved in deformation. This is the first tephra horizon recognized in the high Agri Valley, which, based on the stratigraphic study of the trench, lies in a primary position. 40Ar/39Ar dating constrain its age to 266 ka and provide an important marker for the Middle Pleistocene tephrochronology of the region. Together with dating, geochemical analysis suggests a possible volcanic source in the Campanian region

Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia

This work was financially supported by the MISTRALS/PaleoMex program and by the Project of Strategic Interest NextData PNR 2011–2013 (www. nextdataproject.it). Lionel Savignan is thanked for his participation in the biomarker analysis. Radiocarbon datings for core KESC9-14 have been funded by Institut Carnot Ifremer-EDROME (grant A0811101). We also thank the Holocene North-Atlantic Gyres and Mediterranean Overturning dynamic through Climate Changes (HAMOC) project for financial support. The biomarker data presented here are available in the supporting information.Peer reviewedPublisher PD

The use and beauty of ultra-high-resolution seismic reflection imaging in Late Quaternary marine volcaniclastic settings, Bay of Naples, Italy

A Nápolyi-öbölben felvett ultra nagy felbontású egycsatornás (IKB-Seistec™) reflexiós szeizmikus szelvények korábbi geológiai és geofizikai vizsgálatok eredményeivel együtt kivételes, eddig soha nem látott felbontású szeizmikus leképezését nyújtják a Flegrei-mezők és a Somma-Vezúv felszín alá süllyedt késő-pleisztocén–holocén rétegtani felépí - tésének. A szeizmikus szelvényeken látott geometria és gravitációs magvevővel nyert üledékek adatainak összevetéséből Campania partközeli kontinentális talapzatán számos olyan üledékes és vulkáni szerkezet, valamint hidrotermális jelenség került leképezésre, melyek a legutolsó glaciális maximum (kb. 18 000 év) óta keletkeztek. A Pozzuoli-öbölben mért Seistec szelvények jól mutatják a beomlott kaldera gyűrűs vetőjét, a kb. 15 ezer éves Nápolyi Sárga Tufa (NYT) lerakódáshoz vezető kitöréskor felújuló boltozatot, és alátámasztják a deformáció későnegyedidőszaki korára és stílusára vonatkozó hipotéziseket. A szeizmikus szelvényeken látható a NYT rétegeinek töréses szerkezete, valamint hidrotermális fluidum-feláramlások és vulkáni/szubvulkáni intrúziók a gyűrűs vetők mentén. A Somma-Vezúv rétegvulkán előterében a kontinentális talapzat felett mért szeizmikus szelvények leképezték a Vezúv i.sz. 79-es kitörésekor Herculaneum városát elpusztító piroklaszt-ár tengervízbe érésekor keletkező, gravitációsan összeomló homokhullámok szerkezetét is. A Somma-Vezúv és a Pozzuoli-öböl közti, buckás felszínű Banco della Montagna területén mért szelvények és fúrómagok vulkanoklasztos diapírok sorát tárták fel. Ezeket a konszolidálatlan horzsakőből álló testeket a fluidum - feláramlás és aktív kigázosodás hatására kialakult mélybeli túlnyomás hozta fel a tengerfenékre.Very high-resolution, single channel (IKB-Seistec™) reflection seizmic profiles acquired in the Bay of Naples, com - plemented with geological and geophysical data from the literature, provide unprecedented, superb seismic imaging of the latest Pleistocene–Holocene stratigraphic architecture of the submerged sectors Campi Flegrei and Somma-Vesuvius volcanic districts. Seismic profiles were calibrated by gravity core data and document a range of depositional systems, volcanic structures and hydrothermal features that evolved after the onset of the Last Glacial Maximum (~ 18 ka BP) over the continental shelf on the Campania coastal zone. Seistec profiles from the Pozzuoli Bay yield high-resolution images of the shallow structure of the collapse caldera-ring fault — resurgent dome system associated with the eruption of the Neapolitan Yellow Tuff (NYT) (ca 15 ka) and support a working hypothesis to assess the timing and the styles of deformation of the NYT resurgent structure throughout the latest Quaternary. Seismic images also revealed the nature of the fragile deformation of strata along the NYT ring fault system and the occurrence of hydrothermal fluids and volcanic/subvolcanic intrusions ascending along the ring fault zone. Seismic data acquired over the continental shelf off the Somma-Vesuvius stratovolcano, display evidence of gravit - ational instability of wavy bedforms representing the submarine prosecution of pyroclastic flows originated from the Vesuvius during the eruption that destroyed the Roman city of Herculaneum in 79 CE. At the Banco della Montagna, a hummocky seafloor knoll located between the Somma-Vesuvius and the Pozzuoli Bay, seismic profiles and gravity core data revealed the occurrence of a field of volcaniclastic diapirs formed by the dragging and rising up of unconsolidated pumice, as a consequence of fluid overpressure at depth associated with active degassing and fluid venting at the seafloor

Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia

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A roadmap for amphibious drilling at the Campi Flegrei caldera: insights from a MagellanPlus workshop

Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100–200 km3 Campanian Ignimbrite (CI) eruption at ∼39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25–28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore–offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system

Architecture and 15 ka to present volcano-tectono-sedimentary evolution of the Neapolitan Yellow Tuff caldera offshore the Campi Flegrei, (Naples, Eastern Tyrrhenian Margin)

The Campi Flegrei area is structurally dominated by the caldera associated with the eruption of the Neapolitan Yellow Tuff (NYT), a 40 km3 DRE ignimbrite dated at ca 15 ka BP [Deino et al., 2004], 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, and references therein; Di Vito et al., 1999; Perrotta et al., 2006; Fedele et al., 2011], but its offshore morphology, the stratal geometry of the volcaniclastic products and structures and the late-stage geodynamic evolution of the inner caldera resurgence are still poorly known. We integrate geological and geophysical data obtained from high-resolution reflection seismic profiles (Sparker and Chirp sources) with gravity cores and swath bathymetry to better constrain the shallow structure and 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 volcano-tectono-sedimentary evolution 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 almost at the same rate as the post-glacial sea-level rise. Particularly, the inner Pozzuoli Bay started to deform soon after 15 ka BP, when the 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 resediments, mostly represented by density current deposits, separated by an interval of hemipelagic sediments. The two density flow units display a remarkable difference in their thickness and internal geometry. Across the bay, the lower unit is ca 5m thick in the western sector and reaches its maximum of ca 10 m in the central sector while it is absent towards the east. The upper unit, on the contrary, displays the minimum thickness of 10 m close to the central sector of the bay and increases up to ca 16 and 12 m in the western and eastern sector of the bay, respectively. The variation in thickness of the density flow deposits appears to be related with the amount of sediments available. The upper density flow deposits is also internally more chaotic respect to the lower one, suggesting higher energy and/or turbulence A significant 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. Sections clearly illustrate that the basin depocentre topography is not fixed at one position but migrates southwards in time. We suggest that the uplift of the resurgent dome and subsidence of the southern sector, occurred after the eruption of the NYT, acted as a major control in the increase of the sea-floor gradient in the Pozzuoli bay. This may have triggered in turn, the deposition of gravity flow deposits along with a progressive migration of basin depocentres through time