Pore water expulsion at submarine cold seeps : geochemical evidence for short cuts between crust sediments and ocean Active pore water expulsion from marine sediments has been observed on continental margins worldwide and is therefore considered a potentially important link in global geochemical cycles. Understanding element recycling through submarine fluid discharge on a global scale requires a profound knowledge of the fluids&rsquo; origin and the geochemical processes affecting their composition. The present thesis investigates the chemical and isotopic (delta7Li 87Sr 86Sr 129I I) composition of cold seep fluids as a function of the tectonic context the lithology and thickness of ambient sediments and other relevant geological factors