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

This paper provides a synthesis of the research conducted on the Meishan section D, the Global Stratotype Section and Point of the Permian-Triassic Boundary (PTB), East China. The historical, geographic and geological setting of the section are briefly introduced. Changhsingian to “Griesbachian” conodont and ammonoid zonations, one of the best Permo-Triassic zonations in the world, are presented, with a short discussion on the age of Otoceras. The paper presents a correlation of the Changhsingian to “Griesbachian” magnetostratigraphy along the Meishan section. Recent developments on the chemostratigraphy of δ~ 13 C and δ~ 34 S are introduced, especially the discovery of more than one negative δ~ 13 C excursions across the PTB. Two important molecular findings reveal profound changes at the base of ecosystem—the microbial catastrophe, and the euxinic conditions in the photic zone during the Permian-Triassic superanoxic event. The paper reports changes in the determination of the age of PTB since 2001. According to Mundil et al. (2004) the age of volcanogenic clay bed 25, 14 cm below the PTB, is now set at (252.4±0.3) Ma. A discussion on the event-stratigraphy concludes that, although there is a major event episode at beds 25-26, the events across the PTB at Meishan mountain are multi-episodic and commenced prior to the Event Beds 25-26. Therefore , the possibility that the mass extinction was mainly induced by an extraterrestrial impact is excluded.