Vai (2003) suggested that the area presently occupied by Sicily was a deep marine basin belonging to the ultra-slowspreading Ionian-Tethys Ocean, Early Permian in age. The study of the Hyblean xenolith suite and the reappraisal ofgeophysical data (Manuella et al., 2013) indicate that the unexposed basement of the Hyblean-Pelagian forelandconsists of serpentinized peridotites and minor gabbros, suggesting the existence of oceanic core complex structures(Scribano et al., 2006). Accordingly, the abundance of serpentinites in the oceanic roots of Sicily and its offshore areashints at the presence of huge amounts of water and evaporite-like salts (probably about 10.5 kg of salts per m3 ofserpentinized peridotite) in the Tethys basement of Sicily, as a result of the seawater-driven serpentinization (Manuella,2011). Regarding the Caltanissetta Depression, a thick succession of evaporites (Gessoso-Solfifera Group) wasdeposited in a Miocene marine basin, during Messinian. The most popular climate evaporite theory suggests that deepsalt water basins, having restricted communication with the open ocean, dried out and filled up several times, forming athick sequence of salts. This explanation may be realistic for a salt thickness of few tens of meters (Hovland et al.,2014). Differently, the Caltanissetta succession consists of 250 m of outcropping gypsum and carbonates and about1000 m of buried chlorides. Therefore, we put forward the hypothesis that supercritical fluids, deriving from themassive dehydration of serpentinites due to a geothermal rise, may have remobilized the buried Triassic evaporites assaline brines (supercritical out-salting model; Hovland et al., 2014), during Messinian. These saturated brines wereemplaced as hot “geysers” forming hypersaline ponds at the sea bottom (Hovland et al., 2014), as presently observed inthe numerous deeps in the Red Sea floor.

Formation and accumulation of Messinian evaporites in the Caltanissetta Basin (Sicily) by “supercritical out-salting”: reasons for a Tethys serpentinite connection / Carbone, Serafina; Scribano, Vittorio; Manuella, Fc. - In: RENDICONTI ONLINE DELLA SOCIETÀ GEOLOGICA ITALIANA. - ISSN 2035-8008. - 31(2014), pp. 150-150. ((Intervento presentato al convegno Congresso SGI -SIMP 2014 tenutosi a Milano nel settembre 2014.

Formation and accumulation of Messinian evaporites in the Caltanissetta Basin (Sicily) by “supercritical out-salting”: reasons for a Tethys serpentinite connection

CARBONE, Serafina;SCRIBANO, Vittorio;
2014

Abstract

Vai (2003) suggested that the area presently occupied by Sicily was a deep marine basin belonging to the ultra-slowspreading Ionian-Tethys Ocean, Early Permian in age. The study of the Hyblean xenolith suite and the reappraisal ofgeophysical data (Manuella et al., 2013) indicate that the unexposed basement of the Hyblean-Pelagian forelandconsists of serpentinized peridotites and minor gabbros, suggesting the existence of oceanic core complex structures(Scribano et al., 2006). Accordingly, the abundance of serpentinites in the oceanic roots of Sicily and its offshore areashints at the presence of huge amounts of water and evaporite-like salts (probably about 10.5 kg of salts per m3 ofserpentinized peridotite) in the Tethys basement of Sicily, as a result of the seawater-driven serpentinization (Manuella,2011). Regarding the Caltanissetta Depression, a thick succession of evaporites (Gessoso-Solfifera Group) wasdeposited in a Miocene marine basin, during Messinian. The most popular climate evaporite theory suggests that deepsalt water basins, having restricted communication with the open ocean, dried out and filled up several times, forming athick sequence of salts. This explanation may be realistic for a salt thickness of few tens of meters (Hovland et al.,2014). Differently, the Caltanissetta succession consists of 250 m of outcropping gypsum and carbonates and about1000 m of buried chlorides. Therefore, we put forward the hypothesis that supercritical fluids, deriving from themassive dehydration of serpentinites due to a geothermal rise, may have remobilized the buried Triassic evaporites assaline brines (supercritical out-salting model; Hovland et al., 2014), during Messinian. These saturated brines wereemplaced as hot “geysers” forming hypersaline ponds at the sea bottom (Hovland et al., 2014), as presently observed inthe numerous deeps in the Red Sea floor.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/107107
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