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Rendiconti Lincei

, 17:243 | Cite as

Sediment injection in the pit of the Urania Anoxic brine lake (Eastern Mediterranean)

  • Giovanni Aloisi
  • Davide Castradori
  • Maria Bianca Cita
Article

Abstract

The Urania brine-filled, anoxic basin shows physical and geological characteristics which set it aside from the previously studied anoxic basins of the Eastern Mediterranean. The detailed study of a core raised from the western horn of the horseshoe-shaped basin provides evidence for the upward injection of old sediments into more recent, surficial anoxic mud. The oldest intruded sediments identified are Zanclean in age, and pelagic in facies (MPl3 and MPl4a biozones). Debris-flow or flow-in mechanisms are discussed, but discarded. The sediment injection agrees with the very high bottom water temperatures measured in the pit, the very high heat flow and a concave downwards pore water dissolved chlorosity gradient, all indicative of upward fluid migration. Mud expulsion features were recorded close to the location of the core. Movement along a fault plane could be responsible for the upward injection of old sediments and for their expulsion on the sea-floor.

Key words

Urania Anoxic Basin Sediment Injection Mediterranean Ridge 

Iniezione di sedimenti nel bacino anossico ipersalino Urania (Mediterraneo orientale)

Riassunto

Si presentano i risultati dello studio dettagliato di una carota prelevata in un bacino contenente salamoie anossiche ad alta densità, scoperto nella Dorsale Mediterranea occidentale. Il bacino ha una forma a ferro di cavallo e la sua estremità occidentale contiene una specie di buco profondo circa 80 m, dove la temperatura misurata cresce fino a 45°C. La carota contiene brandelli di sedimenti pelagici di età diversa, del Pleistocene e Pliocene inferiore, che sono interpretati come iniettati verso l’alto da fluidi in pressione lungo un piano di faglia entro i sedimenti anossici superficiali di età più recente. Questa interpretazione è in a ccordo con l’anomalia geochimica riscontrata (gradiente di clorinità inverso misurato nelle acque interstiziali della stessa carota) e con la forte anomalia termica registratain situ e mediante misure del flusso di calore. Questi dati suggeriscono una provenienza dei fluidi da almeno 500 m di profondità.

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Copyright information

© Springer 2006

Authors and Affiliations

  • Giovanni Aloisi
    • 1
  • Davide Castradori
    • 2
  • Maria Bianca Cita
    • 3
  1. 1.Laboratoire de Paléoenvironnements et PaléobiosphèreUniversité Claude Bernard - Lyon I Bâtiment GéodeVilleurbanne CedexFrancia
  2. 2.Gas Business DevelopmentIeoc Production B.V.Il CarioEgitto
  3. 3.Dipartimento di Scienze della Terra «Ardito Desio»Università degli Studi di MilanoMilano

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