Continental earth's crust
the continental earth's crust exists contrary to the oceanic earth's crust from magma tables rocks with middle to high SiO 2 - content, partly powerful sediments and the metamorphic products developed from it. Due to the relative to the oceanic crust high portion of aluminum and the generally high portion of silicon, also the abbreviation Sial (also SiAl) is common for the continental earth's crust.
The density of the continental earth's crust is smaller with approximately 2.7 g/cm 3 than those the oceanic crust. Both “swim” ISO-statically on the asthenosphere. The power of the continental crust amounts to under levels on the average 35 km and rises in accordance with the ISO-static behavior under high mountains on up to 80 km.
the continental earth's crust is divided into an upper, brittle and an underlying, duktilen range. The frontier zone between the ranges is called Conrad Diskontinuität.
Starting from approximately 10-20 km depth pressure and temperature are so high that the main mineral constituent parts of the crust, the quartz and feldspar, when tectonic demand no longer inflexibly, but by creeping at Kristallgrenzen or recrystallization duktil react. Within the duktilen range the earth's crust can be distorted plastic, thus breakless and durably . The situation of the Übergangszone depends on the heat flow and the fluid content of the earth's crust. In magmatisch active regions with increased heat flow and higher fluid concentration the duktile range in smaller depth begins, the earth's crust is more easily distortable therefore.
See also: Internal structure of the earth
|element||brittle range||duktiler range||total portion||of connection||brittle range||duktiler range||total portion|
|of O||46.4||47.9||47.2||SiO 2||58||64.9||61.5|
|aluminium||8.2||,7.7||,8.0||aluminium 2 O 3||15.5||14.6||15.1|
|well||2.1||,2.6||,2.4||well 2 O||2.9||,3.5||,3.2|
|K||1.3||,2.9||,2.1||K 2 O||1.6||,3.5||,2.4|