karbonaatiodating

Karbonaatiodating, also known as radiocarbon dating, is a method for estimating the age of carbon-based archaeological and geological samples by measuring the amount of the radioactive isotope carbon-14 remaining. Carbon-14 is formed in the upper atmosphere and is incorporated into living organisms. When an organism dies, intake stops and 14C decays to nitrogen-14 with a half-life of about 5,730 years. The remaining 14C/12C ratio is used to infer age, with corrections for isotopic fractionation.

There are two main laboratory approaches: accelerator mass spectrometry (AMS) and conventional radiometric dating by beta counting. AMS directly measures the 14C/12C ratio in small samples, often milligram-scale, and is faster and more sensitive. Conventional dating counts the beta decay events and generally requires larger samples and longer counting times.

Calibration is essential because atmospheric 14C levels varied historically. Calibration curves, such as IntCal, align measured radiocarbon ages with calendar dates using independently dated samples like tree rings, corals, and varves. The practical dating range is up to about 50,000 years; beyond that, results become highly uncertain. In marine and freshwater contexts, reservoir effects can make samples appear anomalously old unless corrected.

Applications include archaeology, paleontology, geology, and climate studies. Suitable materials include charcoal, wood, seeds, bone collagen, and some shells, while inorganic carbonates require additional interpretation. Modern developments, including the post-1950s bomb-14C peak, extend dating possibilities for recent materials. Contamination and sample pretreatment remain critical factors in accuracy.