Introduction

It has long been clear that waning stages of the Permian Period and initial phases of the Triassic make up an interval of time during which there were profound changes in the Earth's internal and surficial features, in its atmosphere and climate, and, conspicuously, in its biota. Unfortunately, however, rocks that record this fascinating segment of Earth history are greatly restricted in distribution by comparison with those from which we reconstruct events in earlier Paleozoic or later Mesozoic history. Furthermore, subsequent orogenic cycles have dismembered, effaced, and in other ways complicated the record. In combination, these factors make development of a stratigraphic scale for the Permo-Triassic boundary interval difficult, and this, in turn, serves to insure that the history of the latest Permian and earliest Triassic has been reconstructed thus far in only very general outline.

Project of 203 of the International Geological Correlation Programme (IGCP) was organized in 1984 with the aim of integrating modern studies of rocks and fossils in the Permo-Triassic boundary interval into an internally coherent and well-controlled body of information from which it might ultimately be possible to infer something meaningful about the history of late Paleozoic and early Mesozoic times. The attention of project participants naturally focused on Permian and Triassic strata in the eastern part of the Tethyan realm, in South China and India, for marine rock sequences of this age are most continuously developed there. However, close cooperation with students of the Permian and Triassic in Italy, Hungary, Yugoslavia, Israel, the Soviet Union, Australia, and New Zealand has enabled development of a data base that now includes information for essentially the entire length and breadth of the former Tethys seaway.