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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Actualités volcaniques

A new habitat has just been described: discovered during an expedition in 2015, it is located in the volcanic complex Panarea in the Aeolian Islands.

Located 70-80 meters deep, off the southwestern coast of Basiluzzo Islet, it was named "Smoking Land ", following the presence of a large number of active chimneys .

Map of the Panarea Volcanic Complex, with in the red square the studied area - Bathymetries from ISMAR, reprinted from [24] under license, with permission from ISMAR-CNR, original copyright 2013./ Extract from source document.

Map of the Panarea Volcanic Complex, with in the red square the studied area - Bathymetries from ISMAR, reprinted from [24] under license, with permission from ISMAR-CNR, original copyright 2013./ Extract from source document.

 High-resolution swath bathymetry maps.  A) map of the whole investigated area, SW of Basiluzzo Islet. The black dots indicate the benthic chamber stations; B) map of the Smoking Land hydrothermal field (WGS84, UTM33, cell size 20x20 cm, vertical exaggeration 3X). The black triangles indicate the location of the sampled chimneys, while the black square indicates the location of the chimney reconstructed based on HD video-images. ./ Extract from source document.

High-resolution swath bathymetry maps. A) map of the whole investigated area, SW of Basiluzzo Islet. The black dots indicate the benthic chamber stations; B) map of the Smoking Land hydrothermal field (WGS84, UTM33, cell size 20x20 cm, vertical exaggeration 3X). The black triangles indicate the location of the sampled chimneys, while the black square indicates the location of the chimney reconstructed based on HD video-images. ./ Extract from source document.

Thirty-nine chimneys have been described, different in shape and size, fourteen of which emit hydrothermal fluids of low temperature, marine origin, and characterized by acidic chemical conditions.

The origin of "Smoking Land " can be attributed to the presence of a strong hydrothermal circulation along the fault plane of the northwest graben.

The fluids emitted are not saltier or hotter than the surrounding marine waters, unlike the hot subaerial emissions of Panarea. This suggests a CO2 emanation from deep volcanic rocks that triggers a circulation of seawater and a dissolution of metal rocks under acidic conditions.

The formation of chimneys is the result of the precipitation of Fe2+ of volcanic origin caused by seawater, with the probable support of microbial activity. The structure of the chimneys is mainly composed of amorphous and weakly crystallized iron oxyhydroxides of hydrothermal origin.

Three-dimensional model of "Smoking Land" - A. vertical exaggeration 2x - B. Vertical Exaggeration 3x - Extract of the document cited in source.

Three-dimensional model of "Smoking Land" - A. vertical exaggeration 2x - B. Vertical Exaggeration 3x - Extract of the document cited in source.

Images of reconstructed chimneys, located in the "Smoking Land" - A. HD-video reconstruction of the chimney - B. Underwater image of the anterior side - C. Underwater image of the posterior side, with yellowish deposits and the emission of bubbles - the scale bar is 20 cm for the foreground - Extract of the document cited in source.

Images of reconstructed chimneys, located in the "Smoking Land" - A. HD-video reconstruction of the chimney - B. Underwater image of the anterior side - C. Underwater image of the posterior side, with yellowish deposits and the emission of bubbles - the scale bar is 20 cm for the foreground - Extract of the document cited in source.

ROV surveys revealed a large cover of red algae (Peyssonnelia spp.) colonized by the green alga Flabiella petiolata and suspensivores, mainly sponges, but also bryozoans and tubicole polychaetes.

Although no species specific to vents has been identified, benthic communities found in association with chimneys included more taxa than those found in surrounding rocky areas without vents.

These early discoveries highlight a dynamic underwater habitat where geological, chemical and biological processes are intimately linked, making "Smoking Land " an important site in terms of marine heritage that should be safeguarded and protected, including  frequent marine research expeditions.

Underwater images of the chimneys located in the Smoking Land sampled during the 2015 research survey.  (A) chimney VA; (B-C) chimney SF; (D-F) chimney GB. Scale bars: 20 cm for foreground. - Extract of the document cited in source.

Underwater images of the chimneys located in the Smoking Land sampled during the 2015 research survey. (A) chimney VA; (B-C) chimney SF; (D-F) chimney GB. Scale bars: 20 cm for foreground. - Extract of the document cited in source.

Source : Esposito V, Andaloro F, Canese S, Bortoluzzi G, Bo M, Di Bella M, et al. (2018) Exceptional discovery of a shallow-water hydrothermal site in the SW area of Basiluzzo islet (Aeolian archipelago, South Tyrrhenian Sea): An environment to preserve. PLoS ONE 13(1): e0190710. - https://doi.org/10.1371/journal.pone.0190710 - Link 

© 2018 Esposito et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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