Mantle-derived fluids in Central Mediterranean: Geochemical and geophysical constrains on sources of fluids and migration

Risultato della ricerca: Other

Abstract

The geodynamics of the central Mediterranean ischaracterized by the interaction between the European plateand the African’s. In this setting Sicily is a sector of theAppenine-Maghrebide accretionary prism, which is locatedbetween two areas affected by extensional tectonics (SicilyChannel to the south and the Thyrrenian back arc basin to thenorth).Significant mantle-derived helium (0.4<R/Ra<2.8;R=3He/4He in the sample, Ra in atmosphere) is found in theCH4 and N2-CO2 rich fluids released in central western Sicily,a region without evidence of recent magmatism. CH4-dominated gases are released from mud volcanoes localized inan area of both low heat flow and seismicity. On the contraryCO2 is mainly associated to the thermal groundwatercirculating mainly in Mesozoic limestone over an areacharacterized by high seismicity and heat flow anomaly. Totalcarbon dissolved in thermal water is a mixture of mantlederivedand crustal inorganic CO2, while CH4-dominatedfluids show a mixing between a 3He rich and CH4-poor termand a CH4-rich and 3He-poor one typical of crustal reservoir ofgases. The computed mantle derived He, much higher thanstable continental areas, indicates that the transfer of fluids iscontrolled by tectonic mechanism through the crust. Finally,recent geophysical investigations discovered the occurrence ofactive lithospheric faults that could control the transfer ofmantle derived fluids from the sources to the crust andthroughout this towards the surface.
Lingua originaleEnglish
Numero di pagine0
Stato di pubblicazionePublished - 2013

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