The geochemical era is a stage in geological history characterized by the formation of accumulations of certain chemical elements or their combinations in the earth's crust . Thus, the iron ore era is associated with the beginning of the Lower Proterozoic (about 2500 million years ago ), the era of lead deposits of the Devonian and Carboniferous (1700-1400 million years ago ), the gold ore era of Archean and others. Of practical interest are the epochs associated with the formation of mineral deposits .
The concept was proposed by A.E. Fersman in 1934. Often used the close concept of " metallogenic era ".
The separation of eras is associated with the general conditions for the formation of deposits. Thus, the origin of deposits of ferruginous quartzites ( Kryvyi Rih iron ore basin , Lake Superior , Minas Gerais ) at the end of the Archean - beginning of the Proterozoic is usually explained by the appearance of large amounts of oxygen in the atmosphere and the deposition of iron oxides (before that, the iron remained in solution in the form of bicarbonates). Similarly, the Carboniferous era ( Carboniferous period ) occurred as a result of the flowering of vegetation and the subsequent burial of its remains.
Literature
- Geochemical era // Kazakhstan. National Encyclopedia . - Almaty: Kazakh encyclopedias , 2005. - T. II. - ISBN 9965-9746-3-2 .
- Geochemical era - an article from the Great Soviet Encyclopedia .
- A.A. Yaroshevsky. Geochemical era . // Mountain Encyclopedia. M .: Soviet Encyclopedia. Edited by E. A. Kozlovsky. 1984-1991.
- Fersman A.E., Selected Works, vol. 3, M. , 1955.
- Tugarinov A.I., General Geochemistry, M. , 1973.
When writing this article, material from the publication Kazakhstan. National Encyclopedia ”(1998-2007), provided by the editors of the“ Kazakh Encyclopedia ”under a Creative Commons BY-SA 3.0 Unported license .