The National Geochronological Database
U.S. Geological Survey · Fact sheet · 1996
The National Geochronological Database (NGDB) is a compilation of more than 30,000 individual published K-Ar (with some 40Ar/39Ar), Rb-Sr, U-Th-Pb, Sm-Nd, Pb-cc, and fission-track mineral and rock ages that are reported in the published literature.The basic component of the data file is the record, which contains one or more radiometric ages for the approximately 18,000 dated rock samples from the United States thus far incorporated into NGDB.Coverage is estimated to be about 50 percent of all ages on dated rock samples published through 1991.Accompanying each age is supporting geographic, petrologic, chemical, and interpretive information extracted from the respective publications.