PUMA
Istituto di Scienze Marine     
Taviani M., Angeletti M., Ceregato A., Foglini F., Froglia C., Trincardi F. The Gela Basin pockmark field in the strait of Sicily (Mediterranean Sea): chemosymbiotic faunal and carbonate signatures of postglacial to modern cold seepage. In: Biogeosciences, vol. 10 (7) pp. 4653 - 4671. COPERNICUS GESELLSCHAFT MBH, BAHNHOFSALLEE 1E, GOTTINGEN, 37081, GERMANY, 2013.
 
 
Abstract
(English)
The geo-biological exploration of a pockmark field located at ca. 800 m below sea level in the Gela basin (Strait of Sicily, Central Mediterranean) provided a relatively diverse chemosymbiotic community and methane-imprinted carbonates. To date, this is the first occurrence of such a type of specialised deep-water cold-seep communities recorded from this key region, before documented in the Mediterranean as rather disjunct findings in its eastern and westernmost basins. The thiotrophic chemosymbiotic organisms recovered from this area include empty tubes of the vestimentiferan Lamellibrachia sp., loose and articulated shells of lucinids (Lucinoma kazani, Myrtea amorpha), vesicomyids (Isorropodon perplexum), and gastropods (Taranis moerchii). A callianassid decapod (Calliax sp.) was consistently found alive in large numbers in the pockmark mud. Their post-mortem calcified parts mixed with molluscs and subordinately miliolid foraminifers form a distinct type of skeletal assemblage. Carbonate concretions display delta C-13 values as low as -40% PDB suggesting the occurrence of light hydrocarbons in the seeping fluids. Since none of the truly chemosymbiotic organisms was found alive, although their skeletal parts appear at times very fresh, some specimens have been AMS-C-14 dated to shed light on the historical evolution of this site. Lamellibrachia and Lucinoma are two of the most significant chemosymbiotic taxa reported from various Mediterranean cold seep sites (Alboran Sea and Eastern basin). Specimens from station MEDCOR78 (pockmark#1, Lat. 36 degrees 46'10.18 '' N, Long. 14 degrees 01'31.59 '' E, 815 m below sea level) provided ages of 11736 +/- 636 yr cal BP (Lamelli-brachia sp.), and 9609.5 +/- 153.5 yr cal BP (L. kazani). One shell of M. amorpha in core MEDCOR81 (pockmark#6, Lat 36 degrees 45'38.89 '' N, Long 14 degrees 00'07.58 '' E, 822 m below sea level) provided a sub-modern age of 484 +/- 54 yr cal BP. These ages document that fluid seepage at this pockmark site has been episodically sustaining thiotrophic macrobenthic communities since the end of the Younger Dryas stadial up to sub-recent times.
DOI: 10.5194/bg-10-4653-2013
Subject GULF-OF-MEXICO; CENTRAL ADRIATIC SEA; BIVALVE FAMILY THYASIRIDAE; MUD VOLCANOS; AUTHIGENIC CARBONATES; ACCRETIONARY PRISM; COMMUNITY COMPOSITION; SPATIAL-DISTRIBUTION; BACTERIAL SYMBIOSES; HYDROTHERMAL VENTS


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