General Requirements for Geochronology
- well-documented sampling site(s)– relocatable by others (i.e. principle of scientific reproducibility)
- suitable sample or suite of samples– geologically representative, context of sample(s) understood, preferably simple, with no veins, inclusions, multiple components etc and with all potential complexities well-understood in advance
- dateable– suitable whole-rock mineralogies or minerals (in sufficient abundance and size) that record the parent-daughter element fractionation event and that give an unambiguous, readily interpretable date or age population(s)
- good sample preservation– minimal weathering, disturbance, simple metamorphic history
The greatest impediment to the determination of precise radiometric dates is the generally poor preservation of surface geological samples (particularly important for Rb-Sr, K-Ar, Ar-Ar and U–Pb mineral dates).