An integrated study of seepage through the seabed of the Nile deep-sea fan

点击翻译按钮获取中文摘要

At continental margins fluid and gases are emitted into the ocean via the seafloor. The forms of emissions extend from diffusive flow through the seafloor, to focussed flow through seeps and vents, and can be highly variable in time and space. Fluid seeps are highly dynamic sites where geosphere, biosphere, hydrosphere and atmosphere are linked. Seep fluids (liquids and gases) include hydrocarbons, carbon dioxide, nitrogen and hydrogen sulfide, in addition to water. These energy sources support distinct biological communities and chemosynthetic organisms. Currently, the global inventory of fluid seeps at passive continental margins is growing rapidly, but geological, chemical and biological processes operating at those fluid seeps remain little known. In this regard, important research tasks are deriving methane fluxes in their relevance to climatic changes, evaluation of fluid-triggered instabilities on continental slopes, and hydrocarbon geochemical prospecting in the deep offshore. MEDIFLUX proposes a comprehensive, transdisciplinary investigation of fluid seepage at a site exemplarily rich in a large variety of fluid escape structures on a passive continental margin, the Nile deep-sea fan. Objectives are (1) to describe the geographical distribution, types, geological formation and activity of fluid seeps of the Nile deep-sea fan, (2) to determine the composition of emitted fluids and use this information to infer fluid properties and fluid processes at depth, (3) to understand the controls and mechanisms of chemical element transport and breakdown by seep biota, and to obtain a well constrained budget of element cycling and export at fluid seeps.