Accumulations of melt at the base of young oceanic crust

摘要: As hot, solid rock ascends through the mantle, pressure around it decreases while its temperature approximately adiabatically. During ascent, melting faster than adiabat temperature, and if initial of is high enough, will begin to melt at depth where crosses melting-temperature curve. Models upwelling beneath mid-ocean ridges predict significant production over a zone several tens kilometres wider ridge-axis region suggesting that some ascending must arrive away from ridge axis. Here I report ocean-bottom seismograph observations an uncommon previously unreported marine seismic phase, which provide strong evidence accumulates in sills base young oceanic crust. The phase results conversion compressional (P) waves shear (S) on interaction with crust-mantle boundary (the Moho). This rare very difficult model, but when visible, strikingly prominent usually appears unexpectedly great source-to-receiver ranges. imply presence bodies extremely low rigidity, presumably sills, Moho close receiver. Melt may be fairly mobile crust, allowing accumulate lateral plumbing system locally uplifted between crust underlying thermally expanded mantle. Escape this sea floor responsible for formation off-axis seamounts.