Publication Date:
2021-11-08
Description:
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 (〈150m 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.
Description:
Published
Description:
8396-8414
Description:
5V. Dinamica dei processi eruttivi e post-eruttivi
Description:
JCR Journal
Keywords:
gas geochemistry
;
submarine hydrothermalism
;
Quaternary volcanism
;
Pontine islands
;
geochemical characterization submarine vents
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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