Conrad surface ( Eng. Conrade discontinuity ) - a conditional boundary separating the granite (upper) and basalt (lower) layers of the earth's crust , revealed by the increase in the speed of passage of seismic waves . The velocity of longitudinal seismic waves passing through the Konrad surface increases stepwise from about 6 to 6.5 km / s. In some places, the surface is absent, and the speeds of seismic waves increase gradually with depth. Sometimes, on the contrary, several surfaces of an abrupt increase in velocities are observed.
The surface of Konrad is found in various regions of the continental crust at a depth of 15–20 km, but is absent beneath the oceanic crust .
Content
- 1 Opening
- 2 Literature
- 3 See also
- 4 References
Opening
Named in honor of the Austrian geophysicist W. Konrad , who established its presence in 1925 when studying the earthquake in the Alps . In the mid-20th century, it was discovered that the upper layer of the continental crust consists of acidic rocks, and the lower layer consists of more basic magnesium- rich rocks. Thus, seismologists of that time began to believe that the Konrad surface should correspond to the contact between two chemically different layers of granite and basalt .
However, since the 1960s, this theory has been actively disputed among geologists, since the exact geological significance of the Konrad surface has not yet been clarified. It was not installed during the drilling of the Kola superdeep well .
Literature
- Great Soviet Encyclopedia. - M .: Soviet Encyclopedia. 1969-1978. . Archived on May 18, 2012.
See also
- Earth's crust
- Border of Mokhorovichich