In
biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictiona ...
, a subdiscipline of
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
, a taxon-range zone is the zone between the highest and the lowest
stratigraphic
Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks.
Stratigraphy has three related subfields: lithostra ...
occurrence of a
taxon
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. Taxon-range zones are one of the fundamental
biozone
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 ...
s used in biostratigraphy and are named after the taxon whose range they describe.
Definition
The
International Commission on Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigra ...
defines a Taxon-range zone as follows:
"The body of strata representing the known range of stratigraphic and geographic occurrence of specimens of a particular taxon. It is the sum of the documented occurrences in all individual sections and localities from which the particular taxon has been identified."
So a taxon-range zone is not only a vertical interval, but expands laterally. Taxon-range zones are limited at the top by the surface that connects all highest known stratigraphic occurrences of the taxon and are limited at the bottom by the surface that connects all lowest known stratigraphic occurrences of the taxon.
Local Range
The local range of a taxon is the zone between the highest and the lowest stratigraphic occurrence of a taxon in a particular locality or area.
See also
*
Range offset In geology, range offset is the time difference between the last fossil occurrence of a taxon and the actual disappearance of this taxon. Range offset can be used as a measure of Biostratigraphy, biostratigraphic precision and determines among other ...
References
[ {{cite web , url=http://stratigraphy.org/upload/bak/bio.htm , title= Biostratigraphic Units , last= , first= , date= , website= , publisher=International Commission on Stratigraphy , access-date=11 May 2018 , quote= ]
Biostratigraphy