Geochronology/Potassium–argon dating

The method most commonly used to date the primary standard is the potassium-argon dating technique.

Hypotheses

 * 1) Each time frame or span of time in geochronology has at least one dating technique.
 * 2) Late Jurassic is a time frame and Upper Jurassic is a stratigraphic frame so both are different time frames.
 * 3) The overall size of—or efficiency of carbon export from—the biosphere decreased at the end of the Great Oxidation Event (GOE) (ca. 2,400 to 2,050 Ma).