Biozone

Biozone types. Each rectangle represents bodies of sedimentary rocks and each line a different taxon. The arrows indicate the taxon first or last appearance.

In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties of the surrounding rock.

A biostratigraphic unit is defined by the zone fossils it contains. These may be a single taxon or combinations of taxa if the taxa are relatively abundant, or variations in features related to the distribution of fossils. The same strata may be zoned differently depending on the diagnostic criteria or fossil group chosen, so there may be several, sometimes overlapping, biostratigraphic units in the same interval. Like lithostratigraphic units, biozones must have a type section designated as a stratotype. These stratotypes are named according to the typical taxon (or taxa) that are found in that particular biozone.[1]

The boundary of two distinct biostratigraphic units is called a biohorizon. Biozones can be further subdivided into subbiozones, and multiple biozones can be grouped together in a superbiozone in which the grouped biozones usually have a related characteristic. A succession of biozones is called biozonation. The length of time represented by a biostratigraphic zone is called a biochron.[2][3]

  1. ^ Nichols, Gary (2009-06-10). Sedimentology and stratigraphy (Second ed.). Wiley-Blackwell. ISBN 978-1-4051-3592-4.
  2. ^ "Biochronology and biochron boundaries: A real dilemma or a false problem? An example based on the Pleistocene large mammalian faunas from Italy". ResearchGate. Retrieved May 10, 2017.
  3. ^ Cite error: The named reference ICS was invoked but never defined (see the help page).