The Zannone Giant Pockmark: First evidence of a giant complex seeping structure in shallow-water, central Mediterranean Sea, Italy

Ingrassia, Michela; Martorelli, Eleonora; Bosman, Alessandro; Macelloni, Leonardo; Sposato, A.; Chiocci, Francesco Latino

doi:10.1016/j.margeo.2015.02.005

Cited by 44 publications

(43 citation statements)

References 74 publications

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“…The multibeam bathymetry shows that the four depressions (DA, DB, DC, and DD) are morphologically similar to the ZGP described by Ingrassia et al . [], even if they are smaller in size and their seabed morphology is less complicated. More in detail, depressions DB, DC, and DD are similar for the occurrence of mounds, small cones, ridges, and pockmarks.…”

Section: Discussionmentioning

confidence: 99%

“…In general, the large size and complex shape of these depressions appears to be the result of the coalescence of different pockmark/crater‐like features, 50 to 350 m wide (e.g., depressions DA, DB, and DC). A similar situation has been observed at the ZGP, where the complex shape seems to be related to the coalescence of 200 to 500 m wide crater‐like features [ Ingrassia et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…In fact, their present‐day morphology would testify occurrence of multiple episodes of vigorous/explosive fluid emission, possibly favored by mechanisms of self‐sealing due to the formation of authigenic pavements and collapse of sediment, as proposed by Ingrassia et al . [] for the ZGP.…”

Section: Discussionmentioning

confidence: 99%

“…The ZGP (Figures a and 3 of Ingrassia et al . []) has an irregular shape, with the minimum axis of 500 m in the E‐W direction and the maximum axis of 900 m in the NNW‐SSE direction. It is bounded by well‐defined, irregularly trending scarps that are locally subcircular to subrectilinear in shape; to the north the depression boundary is represented by a rocky escarpment.…”

Section: Study Areamentioning

confidence: 99%

“…These elements are dispersed throughout the depression, so that areas with a smooth and regular morphology are mostly absent. The irregular morphology of the ZGP floor and the shape of its margins suggest coalescence of 200–500 m diameter crater‐like features [ Ingrassia et al ., ]. The deepest crater (about 15 m deep) is located in the northern sector of the ZGP and is about 250 m wide.…”

Section: Study Areamentioning

confidence: 99%

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Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

Martorelli

Italiano²,

Ingrassia

et al. 2016

JGR Solid Earth

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Discoveries from multibeam bathymetry and geochemical surveys performed off Zannone Island (western Pontine Archipelago, Tyrrhenian Sea) provide evidence of an undocumented hydrothermal field characterized by ongoing fluid emissions and morphologically complex giant depressions located in shallow water (<150 m water depth). Based on a detailed morpho‐bathymetric study we identify the seabed morphologies produced by hydrothermal fluid emission activity. We recognize five giant depressions (length >250 m) that host pockmarks, mounds, small cones, and active fluid vents, which are interpreted as complex fluid‐escape features developed both through vigorous‐explosive events and steady seepage. Their spatial distribution suggests that the NE‐SW trending faults bounding the Ponza‐Zannone structural high and the shallow fractured basement are favorable conditions for the upward migration of hydrothermal fluids. Moreover, we performed a detailed geochemical study to investigate the source of the hydrothermal fluids. The geochemical signature of the collected fluids provides information of active CO2‐dominated degassing with a significant contribution of mantle volatiles, with measured 3He/4He values > 3.0 Ra that are similar to those recorded at Stromboli and Panarea volcanoes. The hydrothermal system produces volatiles that may originate from residual magma batches, similar to the Pleistocene trachytes cropping out in the SE sector of Ponza Island that were probably intruded in the shallow crustal levels and never erupted. The discovery of the Zannone hydrothermal field updates the record of active hydrothermal areas of the Mediterranean Sea. Moreover, the recognition of several giant hydrothermal depressions characterized by a complex morphology is peculiar for the Mediterranean Sea.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

Martorelli

Italiano²,

Ingrassia

et al. 2016

JGR Solid Earth

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Cold Seep Systems

et al. 2017

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The Ventotene Volcanic Ridge: a newly explored complex in the central Tyrrhenian Sea (Italy)

et al. 2016

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New high-resolution geophysical data collected along the eastern margin of the Tyrrhenian back-arc basin, in the Pontine Islands area, reveal a ∼NW-SE elongated morphological high, the Ventotene Volcanic Ridge (VR), located on the northern edge of the Ventotene Basin. High-resolution multibeam bathymetry, combined with magnetic data, multi- and single-channel seismic profiles, and ROV dives, suggest that VR results from aggregation of a series of volcanic edifices. The summit of these volcanoes is flat and occurs at about 170 m water depth. Given their depths, we propose that flat morphologies were probably caused by surf erosion during Quaternary glacial sea level lowstands. Seismic stratigraphy together with magnetic data suggest that the volcanic activity in this area is older than 190–130 ka age and may be coeval with that of Ventotene Island (Middle Pleistocene). The submarine volcanoes, located 25 km north of Ventotene, are part of a ∼E-W regional volcanic alignment and extend the Pontine volcanism landward toward the Gaeta bay. Integration of structural data from multichannel seismic profiles in this sector of the eastern Tyrrhenian margin indicates that several normal and/or transtensional faults, striking WNW-ESE, NNW-SSE, and NE-SW, offset the basement and form alternating structural highs and depressions filled by thick, mostly undeformed, sedimentary units. Arc-related magmatism is widespread in the study area, where the VR is placed at the hangingwall of the west-directed Apennines subduction zone, which is undergoing tensional and transtensional tectonics. Bathymetric and topographic evidence shows that VR lies in between a major NE-SW trending escarpment east of Ponza and a NE-SW trending graben southwest of the Roccamonfina volcano, a NE-SW transfer zone that accommodate the extension along this segmented portion of the margin. This suggests that the interaction between NE-SW and NW-SE trending fault systems acts as a structural control on location of eruptive centers, given that main volcanic edifices develop along the NW-SE direction, compatible with the extensional setting of the Tyrrhenian basin

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The Zannone Giant Pockmark: First evidence of a giant complex seeping structure in shallow-water, central Mediterranean Sea, Italy

Cited by 44 publications

References 74 publications

Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

Cold Seep Systems

The Ventotene Volcanic Ridge: a newly explored complex in the central Tyrrhenian Sea (Italy)

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