The end-Permian mass extinction was the most severe loss of marine and terrestrial biota in the last 542 My. Understanding its cause and the controls on extinction/recovery dynamics depends on an accurate and precise age model. U-Pb zircon dates for five volcanic ash beds from the Global Stratotype Section and Point for the Permian-Triassic boundary at Meishan, China, define an age model for th...

In 1989, the International Commission on Stratigraphy established a Working Group on the Terminal Proterozoic Period. Nine years of intensive, multidisciplinary research by scientists from some two dozen countries have markedly improved the framework for the correlation and calibration of latest Proterozoic events. Three principal phenomena--the Marinoan ice age, Ediacaran animal diversificatio...

The Vergol locality (Montbrun-les-Bains, South-East France), a candidate section for the Valanginian GSSP (Global Stratotype Section and Point), was studied in detail ammonites calcareous nannofossils. A bed-by-bed sampling quantitative approach were carried out on this expanded succession presenting continuous record of calcareous-marl alternations covering uppermost Berriasian lowermost Valan...

The Global Stratotype Section and Point (GSSP) of the Silurian/Devonian boundary, Lower Devonian Series Lochkovian Stage was formally placed in 1977 at Klonk, Czech Republic, first appearance graptolite Uncinatograptus uniformis (Přibyl). However, since then, correlation this limit has been often hampered carbonate facies where graptolites are uncommon or totally absent. A large calcareous depo...