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

Abstract

Very high-resolution, single channel (IKB-Seistec™) reflection profiles acquired offshore the Napoli Bay, complemented 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 (ca. 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 BP) 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/sub-volcanic intrusions ascending along the ring fault zone. Seismic data acquired over the continental shelf off the Somma-Vesuvius stratovolcano, display evidence of gravitational instability of sand wave deposits originated by the underwater modification of pyroclastic flows that entered the seawater after destroying the Roman city of Herculaneum during the 79 CE eruption of Vesuvius.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.

Integrated on‐land‐offshore stratigraphy of the Campi Flegrei caldera: New insights into the volcano‐tectonic evolution in the last 15 kyr

“…Our reconstruction of the Pozzuoli Gulf stratigraphy was mainly based on a set of high‐resolution seismic profiles (Seistec_2013) acquired using the uniboom IKB‐Seistec profiler (Mosher & Simpkin, 1999; Sacchi et al, 2019; Simpkin & Davis, 1993) by ISMAR‐CNR of Naples in 2013 (Figure 1b). With a source frequency range between 1 and 20 kHz and a central frequency of 2 kHz, the theoretical vertical resolution is 0.2 m, with an average velocity of 1500 m/s.…”

“…With this scope, several studies have assessed the stratigraphy of the offshore caldera basin‐fill using seismic reflection datasets of different vintages and resolution (Aiello et al, 2012, 2016; Fusi et al, 1991; Milia, 1998; Milia et al, 2000; Natale et al, 2020; Pescatore et al, 1984; Sacchi et al, 2014, 2019; Steinmann et al, 2016, 2018). In this work, we benefit from a blend of high‐ and very‐high‐resolution seismic profiles, and provide a detailed stratigraphic framework for the submerged part of the caldera and integrate the marine record of the Pozzuoli Gulf with both the La Starza marine succession on‐land and the whole continental tephrostratigraphic records of the caldera.…”

The Coastal Areas of the Bay of Naples: The Sedimentary Dynamics and Geological Evolution of the Naples Canyons

“…The submarine canyons are significant erosional features of the sea bottom, cutting deeply through long belts of continental slopes and serving as a primary conduit through which both siliciclastic and volcaniclastic materials emanating from the coastal zones reach the deep oceanic basins [9][10][11][12][13][14][15]. Geological research on the Neogene evolution of the main continental margins of the Mediterranean, North Atlantic, and Pacific areas has confirmed the occurrence of large palaeo-channels, often interlayered in the Quaternary deposits of the sedimentary basins, suggesting that the origin of these kinds of canyons could be genetically related to the subaerial environment [16][17][18][19][20][21][22][23][24][25]. The morphology and the geologic evolution of the submarine canyons located on the main continental margins of the world, based on their morphological parameters, have been deeply studied [18], including the depth range, the slope gradient, the trending of both the canyon and the related tectonic lineaments, the canyon's shape (depositional U-shape and erosional V-shape), and the canyon's profile (rectilinear or meandering).…”