Incompatible item

from Wikipedia, the free encyclopedia

In petrology and geochemistry, incompatible elements or incompatible trace elements are those chemical elements which, due to their ionic charge or radii, do not fit into the crystal structure of normal rock-forming minerals, which is why they mainly occur in pegmatites .

During the fractional crystallization of magma and the formation of magma due to partial melt in the earth's mantle , incompatible elements preferentially enter the melt or remain in it. This mainly happens in cases in which the distribution coefficient between rock-forming minerals and melt is significantly smaller than 1.

In geology, standardized so-called spider diagrams are used in order to be able to provide information about the crystallization behavior of a magma, for example; the elements on the left are always the most incompatible.

Two groups of incompatible elements are referred to with acronyms that come from English .

LILE

The first group has large ionic radii , it is called ' LILE ' ( large-ion lithophile elements ). These include:

These elements are considered to be relatively mobile and fleeting.

HFSE

The second group contains elements with high ionic valencies , they are called ' HFSE ' ( high field strength elements ). These include:

These elements are considered to be relatively immobile.

Individual evidence

  1. http://webdoc.sub.gwdg.de/diss/2000/nagel/rnakap9.pdf
  2. a b H. Brätz, M. Okrusch: The metabasites of the KTB main borehole: Petrographic and geochemical investigations on the core material from the depths of 6242 and 8080 m. In: Geologica Bavaria, 101, geoscientific investigations in the area of ​​continental deep drilling (KTB), Upper Palatinate, 1996.

literature

  • Myron G. Best: Igneous and Metamorphic Petrology . WH Freemann & Company, San Francisco 1982, ISBN 0-7167-1335-7 , pp. 54-55, 100 .
  • Brian Mason, Carleton B. Moore: Fundamentals of Geochemistry . 1st edition. Enke Verlag, Stuttgart 1985, ISBN 3-432-94611-2 , pp. 53-54 .