U at the time of sample formation must be known or calculated.
Note that to calculate an age using this technique the ratio of uranium-234 to its parent isotope uranium-238 must also be measured.
U-Th ages obtained by mass spectrometry in corals from Barbados: sea level during the past 130,000 years.
Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U-Th ages from Barbados corals.
Uranium series dating of impure carbonates: an isochron technic using total sample dissolution.
A large drop in atmospheric 14C/12C and reduced melting in the Younger Dryas, documented with 230Th ages of corals.