A Review on the Global Stratotype Section and Point of the Permian-Triassic Boundary

This paper provides a synthetic review of researches on Meishan Section D, the Global Stratotype Section and Point of the Permian-Triassic Boundary (PTB). The history of research, geographic and geological setting of the section are briefly introduced. Changhsingian to “Griesbachian” conodont and ammonoid zonations, the most perfect Permo-Triassic zonations over the world, are presented, with a short discussion on the age of Otoceras. The Changhsingian to “Griesbachian” strata are subdivided into three 3rd order sequences, and the sedimentary structure of each sequence is indicated. The paper presents a correlation of the Changhsingian to “Griesbachian” magnetostratigraphy of the Meishan section with the general scale, and informed the negation of a short magnetic reversal at the PTB suggested by Zhu and Liu (1999). Recent developments of chemostratigraphy of δ13C and δ34S are introduced, especially the discovery of more than one negative δ13C excursions across the PTB. Two important molecular researches reveal the profound changes at the base of eco-system, the microbial catastrophy, and the euxinic conditions in the photic zone during the Permian-Triassic superanoxic event. The paper reports the changes in dating the age of PTB since 2001. According to recent achievements, the age of volcanogenic claybed 25, 14 cm below the PTB, is now set at 252.4±0.3 Ma. A discussion on the eventostratigraphy concludes that, although there is a major event episode at beds 25–26, the events across the PTB at Meishan are multi-episodic and commenced prior to the Event Beds 25–26, thus the possibility that the mass extinction was mainly induced by an exterrestrial impact is largely excluded.