To use all functions of this page, please activate cookies in your browser.
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
- My watch list
- My saved searches
- My saved topics
- My newsletter
Geothermobarometry is the science of measuring the previous pressure and temperature history of a metamorphic or intrusive igneous rocks. Geothermobarometry is a combination of geobarometry, where a pressure of mineral formation is resolved, and geothermometry where a temperature of formation is resolved.
Additional recommended knowledge
Geothermobarometry relies upon understanding the temperature of formation of minerals within metamorphic and igneous rocks, and is particularly useful in metamorphic rocks. There are several methods of measuring the temperature or pressure of mineral formation relying on chemical equilibrium between metamorphic minerals or by measuring the chemical composition of individual minerals.
These methods rely on the fact that, for a given mineral the composition of the mineral changes systematically: with temperature; with pressure; and also due to the distribution of component elements between the mineral and other minerals with which it is in contact, such as biotite in the case of garnet in a metamorphic rock.
Data on the geothermometers and geobarometers is derived from both laboratory studies on artificial mineral assemblages, where minerals are grown at known temperatures and pressures and the chemical equilibrium measured directly, and from calibration using natural systems.
For example, one of the best known and most widely applicable geothermometers is the garnet-biotite relationship where the relative proportions of Fe and Mg in garnet and biotite change with increasing temperature, so measurement of the compositions of these minerals to give the Fe-Mg distribution between them allows the temperature of crystallisation to be calculated, given some assumptions.
In natural systems, the chemical reactions occur in open systems with unknown geological and chemical histories, and application of geothermobarometers relies on several assumptions that must hold in order for the laboratory data and natural compositions to relate in a valid fashion:
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Geothermobarometry". A list of authors is available in Wikipedia.|