Lithostatic pressure
As a lithostatic pressure rsp. (from old / new Greek : λίθος lithos [. m] -, stone ',' rock ') is in geophysics , geology and Geotechnical Engineering that pressure in the lithosphere designated (crust and part of the mantle), the overlying layers of rock by exercise their weight .
This specific pressure creates an isotropic stress field.
definition
The formula is:
The exact spelling is:
- Used sizes:
- → pressure
- → depth
- → mechanical tension
- → strength
- → area
- → Density of the rock
- → gravitational acceleration
While the hydrostatic pressure increases by 1 bar every 10 m with increasing water depth , the increase in rock layers is about 3 times. The exact proportions depend primarily on the rock density, which is between 2 and 3.3 g / cm³ in the earth's crust ( sediments about 2 g / cm³, granite and limestone 2.7 g / cm³ and gabbro 3.3 g / cm³ ).
In the upper mantle , the rocks are once again more compact (e.g. olivine 3.3 to 4 g / cm³, under very high pressure even 5 g / cm³). Therefore, the exact calculation of internal pressures is one of the most difficult tasks for seismology and applied geophysics .
At the transition between the upper and lower mantle - at a depth of around 700 km - the pressure is around 25 G Pa , which corresponds to 250,000 times the air pressure .
See also
Web links
- Causes of rock metamorphosis - pressure control factor at PETROgraph, Free University of Berlin
- Shell construction at the Christian Albrechts University in Kiel
- Stress ellipsoid and stress types at the Ernst Moritz Arndt University of Greifswald
- Lecture General Geology (PDF file, 864 kB) by E. Wallbrecher, Karl-Franzens-University Graz
- Introductory seminar structural geology (PDF file, 2.25 MB) by E. Wallbrecher, Karl-Franzens-University Graz
- The determination of pressure and temperature during rock transformation (metamorphosis) (PDF file, 7.68 MB) by Bernhard Schulz, Institute for Mineralogy, Technical University Bergakademie Freiberg
- Metamorphosis is not the same as metamorphosis - Different types of metamorphosis (PDF file, 224 kB) by Katrin Wellnitz, Steinmann Institute for Geology, Mineralogy and Paleontology , Rheinische Friedrich-Wilhelms-Universität Bonn
- Petrology of igneous rocks and metamorphic rocks: Part of Metamorphic rocks, lecture 1 (PDF file, 1.5 MB) by JG Raith, Department of Applied Geosciences and Geophysics - Mineralogy & Petrology , Montanuniversität Leoben