Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Alteration

Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_56-2

Definition

Alteration in geochemistry refers to processes by which the mineralogy, composition, and texture of a rock are changed as a result of re-equilibration under conditions of lower temperature and pressure or through interaction with aqueous or CO2-rich fluids. The minerals of the original rock, which may be magmatic, sedimentary, or metamorphic, are transformed into an assemblage of low-temperature, usually finer-grained minerals. A typical example is the replacement of magmatic minerals such as olivine, pyroxene, and feldspar by chlorite, clay minerals, or carbonates. Weathering is a type of alteration that takes place close to the surface through interaction of rock with the atmosphere and with ground- or surface waters. Alteration is also used in chemistry and biology (e.g., DNA alterations).

See Also

Keywords

Surface Water Clay Mineral Bioorganic Chemistry Original Rock Magmatic Mineral 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Maison des GéosciencesLGCA, Université J. FourierSt-Martin d’HèresFrance