Conrad discontinuity

The Conrad discontinuity is a horizontal seismic border zone or area in the nichtorogenen continental crust in about 10-20 km depth at which the velocity of seismic P- waves jumped from 6.5 km / s ( below ) after 5.6 km / s ( above ) changes.

The discontinuous change in the wave velocity at the Conrad discontinuity was first observed by the Austrian seismologists and climatologists Victor Conrad (1876-1962) in 1923. It has been found since then in all continental blocks, but is not a universal phenomenon and it can be shown everywhere. It represents in terms of the internal structure of the earth a common seismic definition of the boundary between upper and lower continental crust dar. continental drilling depth (eg, the continental deep drilling ( KTB ) in Germany and the hole on the Russian Kola peninsula ) do not have proof can provide a petrologic anomaly within this boundary zone. At this depth (10-20 km ) is the rock of the continental crust is usually present in the metamorphic amphibolite facies. The Conrad discontinuity is less well known than the Mohorovicic discontinuity, the seismic boundary between Earth's crust and mantle in the earth sciences.