Geochronology: Magnetostratigraphic Dating

Abstract

Magnetostratigraphy is the subdiscipline of stratigraphy that aims to divide the stratigraphic record into intervals of homogeneous magnetic polarity, named magnetozones. Each magnetozone corresponds to a period of Earth history, named geomagnetic chron (or chron), limited by two geomagnetic field reversals. Since field reversals are globally isochronous, magnetostratigraphic divisions are true chronostratigraphic (time) units. A correlation with the Geomagnetic Polarity Time Scale (GPTS) is achieved if the sequence of magnetozones finds a pattern match with a sequence of reversals in the GPTS. In achieving this, absolute ages of geomagnetic reversals can be assigned to every magnetozone boundary in a local stratigraphic section. Magnetostratigraphy has been used to correlate fragmentary records from disparate regions, in order to build, in association with biostratigraphy and geochronology, a comprehensive Geological Time Scale.