8.12 – Geochronometry of Marine Deposits

The chronometry of marine deposits ultimately depends on accurate calibration by radioactive methods. All absolute dating methods that have proven dependable are based on radioactive decay. Virtually all of the methods depend on the methodical decrease the amount of the radioactive nuclide and the growth of the corresponding daughter product. These nuclides include 14 C, the 238 U, and 235 U decay series and cosmogenic nuclides such as 10 Be and 32 Si which add to the list of usable cosmogenic nuclides. Corals, deep-sea sediments and ferromanganese crusts have all been dated using these nuclides. Volcanic deposits are datable using the K–Ar method.