Numerous results obtained since 1964 are presented. A scheme of the reliability and accuracy of the different chronometers used for numerical dating is given. All the rocks and minerals are not of identical value. Some comparisons between Rb-Sr and K-Ar data are mentioned and comparisons between different chronometers are presented.
The probable numerical age of the boundaries between the stages are discussed, taking into account the new suggestions on the best position of these stratigraphic subjective boundaries.
The Paleogene has a duration of 42 million years65 to 23 m.y. The Paleocene-Eocene boundary is at about 51 m.y. The appearance of Pseudohastigerina is a little more than 52 m.y. ago. The Lutetian stage is between 45.5 and 40 m.y. The base of the Ericsonia subdisticha zone is younger than 37 m.y. while the Priabonian-Rupelian boundary is between 34.5 and 36.5 m.y. All the apparent ages are calculated with the new standardized constants proposed during this symposium.
Figures & Tables
Contributions to the Geologic Time Scale
Containing papers given at the Geological Time Scale Symposium in 1976, this volume begins with a review of dating and correlation, and includes papers on the topics of: geochronoloic scales, biochronology, the magnetic polarity time scale, the potassium-argon isotopic dating method, isotopic methods, and worldwide Permian chronostratigraphy, among others.