Metagenesis ( other Greek μετα- - “between”, “after”, “through” and γένεσις - “origin”, “occurrence”) - transformation of sedimentary rocks when immersed in the lithosphere under the influence of high temperature and pressure in the presence of mineralized solutions [1] [2] .
One of the stages of lithogenesis [3] . It comes after catagenesis and precedes metamorphism [4] . It differs from catagenesis in that it covers the whole rock, and not its individual components [1] [4] .
During metagenesis, recrystallization of authigenic minerals and clay material, dissolution of some minerals and crystallization of others, including the main rock-forming ones, occur [2] [4] . In particular, clay minerals turn into mica , aluminum hydroxide into corundum , hydro goethites into hematite [1] [4] . Stratification of rocks during metagenesis is often preserved [1] [4] .
Metagenesis results in metamorphosed sedimentary rocks (intermediate between sedimentary and metamorphic ). At an early stage of metagenesis, these are, in particular, shales , sandstones , quartzites , crystalline limestones , anthracites ; at the late - aspid and phyllite-like schists [2] .
Term History
The term “metagenesis” was proposed in 1957 by N. B. Vassoevich , who understood the stage of metamorphism as it , but this definition did not take root [2] . In the same year, A. G. Kossovskaya , N. V. Logvinenko, and V. D. Shutov [5] (who called this stage regional metamorphism) called metagenesis an earlier stage - early metamorphism (part of the stage that Vassoevich called catagenesis) [2 ] . In 1960, N. M. Strakhov used the name “metagenesis” for all changes in sedimentary rocks after their formation ( diagenesis ), except for metamorphism and weathering (thus, Strakhov’s metagenesis is equivalent to Vassoevich’s catagenesis and epigenesis along with Kossovskaya’s and others). In Strakhov, metagenesis is divided into catagenesis and protometamorphism [2] .
Notes
- ↑ 1 2 3 4 Metagenesis // Mountain Encyclopedia in five volumes. Volume 3: Kengan - Orth. / ch. ed. E.A. Kozlovsky. - M .: Soviet Encyclopedia, 1987.- S. 307. - 592 p.
- ↑ 1 2 3 4 5 6 Metagenesis // Geological Dictionary in two volumes. Volume 1 (A — L) / rev. ed. K.N. Paffengoltz. - 2, corrected. - M .: Nedra, 1978. - S. 428-429. - 487 p.
- ↑ Lithogenesis // Malaya girnicha encyclopedia in three volumes. Volume 2. L — R. / Ed. V.S. Bіletsky. - Donetsk: Donbas, 2007 .-- S. 36. - 652 p. - ISBN 57740-0828-2 .
- ↑ 1 2 3 4 5 Metagenesis // Malaya girnicha encyclopedia in three volumes. Volume 2. L — R. / Ed. V.S. Bіletsky. - Donetsk: Donbas, 2007 .-- S. 85. - 652 p. - ISBN 57740-0828-2 .
- ↑ Kossovskaya A. G., Logvinenko N. V., Shutov V. D. On the stages of formation and change of terrigenous rocks // Doklady AN SSSR. - 1957. - T. 116 , No. 2 . - S. 293-296 .