Overprinting (geology) explained

thumb|In this orthogneiss from the Czech Republic the original igneous rock texture has been overprinted by foliation associated with metamorphism.

Overprinting is a geological process that superimposes a set of characteristics on rock that partially obscure earlier characteristics. Examples include metamorphic overprinting (superimposed metamorphism[1]), in which new structure,[2] texture, or mineral composition is imposed on existing rock.[3] For example, the Tauern window of Alps contains beds that were originally metamorphosed to eclogite but have since been overprinted to the blueschist and then the greenschist facies. Likewise, deformation associated with the Mazatzal orogeny in Arizona and New Mexico, US, was subsequently overprinted by deformation associated with the Picuris orogeny.[4]

Geochemical signatures can also be overprinted when the geochemistry of a geological body is changed by eliminating or modifying the earlier geochemical signature.[5]

Notes and References

  1. Book: Yardley . Bruce W. D. . An Introduction to Metamorphic Petrology . 1989 . Longman Scientific & Technical . Harlow, Essex, England . Longman Earth Science Series . 0-582-30096-7 . registration. 246.
  2. Book: Jackson . Julia A. . Glossary of geology. . 1997 . American Geological Institute . Alexandria, Virginia . 0922152349 . Fourth . metamorphic overprint.
  3. Zhao . Lei . Zhai . Ming-Guo . Nutman . Allen P. . Oh . Chang-Whan . Bennett . Vickie C. . Zhang . Yanbin . Archean basement components and metamorphic overprints of the Rangnim Massif in the northern part of the Korean Peninsula and tectonic implications for the Sino-Korean Craton . Precambrian Research . July 2020 . 344 . 105735 . 10.1016/j.precamres.2020.105735. 218819425 .
  4. Mako . Calvin A. . Williams . Michael L. . Karlstrom . Karl E. . Doe . Michael F. . Powicki . David . Holland . Mark E. . Gehrels . George . Pecha . Mark . Polyphase Proterozoic deformation in the Four Peaks area, central Arizona, and relevance for the Mazatzal orogeny . Geosphere . December 2015 . 11 . 6 . 1975–1995 . 10.1130/GES01196.1. free .
  5. Brewer . Timothy S. . Menuge . Julian F. . Metamorphic overprinting of SmNd isotopic systems in volcanic rocks: the Telemark supergroup, southern Norway . Chemical Geology . March 1998 . 145 . 1–2 . 1–16 . 10.1016/S0009-2541(97)00114-9.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Overprinting (geology)".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.