GMPV22Fluid-rock interaction processes in the oceanic lithosphere and their significance for elemental cycling in subduction zones and the deep Earth
During its lifetime, the oceanic lithosphere is subjected to fluid-rock interaction processes causing changes in physical and chemical properties. These changes take place over a wide range of temperatures and pressures, from high-temperature hydrothermalism near ridge axes over ubiquitous low-temperature seawater alteration to high-pressure dehydration in subduction zones. In this context, serpentinization plays a key role: at oceanic ridges intense hydrothermal reactions of rocks with magmatic gases and seawater take place. The fluids stored in resulting secondary minerals are transported into subduction zones, where dehydration triggers mantle wedge melting and metasomatic reaction. Both in situ sampling of oceanic crust and mantle and investigations of exhumed portions thereof on land (i.e. ophiolites, high-pressure terranes) provide critical information about the chemical and mineralogical effects as well as the spatial extent of these processes. This session will be devoted to an interdisciplinary approach studying metamorphic and metasomatic processes taking place over the lifetime of the oceanic lithosphere, from mid-oceanic ridges to subduction zones. We welcome contributions dealing with both recent and ancient oceanic lithosphere and focusing on the following topics: a) mineral phase relations as indicators for pressure-temperature-fluid conditions; b) geochronology of metamorphic and metasomatic processes; c) relevance of fluid-rock interaction for global chemical cycles; d) interplay between hydration/dehydration and the physical properties of rocks.
The session will furthermore be devoted to the study of serpentinization processes using different approaches: 1) crystal chemistry, petrology, geochemistry and thermodynamics of serpentine minerals and serpentinite rocks, 2) physical properties of serpentines/serpentinites and related geodynamics and seismicity, 3) fluids and mineral properties and their implications regarding the transport/concentration, recycling in space and time of elements and molecules having potentially major societal implications (abiotic hydrogen, organic molecules, trace and REE elements, etc.).