MANTLE EDUCTION - TECTONIC FLUIDIZATION AT DEPTH

Recent direct observations in trench environments demonstrate that massive volumes of wet sediments are subducted. The gas phases in and near trench zones also show the evidence for subduction of organics and ocean fluids. Serpentine sea mounts also show that large quantities of serpentine are subducted. Thus in the upper layers of the subducting slab metamorphic processes must generate fluidized beds which may be extruded along the subduction faults or intruded by hydraulic fracture mechanisms into the overlying cover rocks. This process which we term eduction, may account for some of the exotic assemblages containing high-pressure rocks found in subduction assemblages, the equivalent of deep mud dykes and volcanoes. The same process may be associated with seismic events.