MULTIDISCIPLINARY HIGH-RESOLUTION CORRELATION OF THE PERMIAN-TRIASSICBOUNDARY

Biostratigraphic correlation of the ten most important Permian-Triassi c boundary sections throughout Tethys enables establishment of four co nodont and ammonoid subdivisions within a stratigraphic interval, one to a few metres thick, representing less than 1 Ma. In ascending order , they are conodonts (Clarkina changxingensis-C. deflecta Zone; Hindeo dus typicalis Interval; Isarcicella parva Zone and I. isarcica Zone) a nd ammonoids (Pseudotirolites-Pleuronodoceras Zone, lower Otoceras Zon e, upper Otoceras Zone and Ophiceras Zone). Most of them can be traced to North America and the Arctic region. Carbon isotope investigations of 24 sections along Tethys and in Greenland and Spitzbergen confirm the consistency of delta(13)C negative excursions at the Permian-Trias sic boundary, together with an inconsistent Ir anomaly. Eight sections show that in most cases there is a succession of: Ir anomaly (denotin g the end-Permian catastrophic environment); delta(13)C excursion (bio mass loss, extinction); P/T boundary (origination of newcomers; potent ially capable of intercontinental correlation within that short time i nterval). There is an intercontinental sequence boundary at the top of the Permian, and a transgressive surface at the P/T boundary followed shortly by a maximum flooding surface. An intercontinental anoxia eve nt accompanied the transgression. Three delineations of the mass extin ction phases and three population explosions have been recognized and can be more or less correlated in South China and the Southern Alps. R adiometric dating of the volcanogenic boundary clays of Meishan, Shang si and the main-stage Siberian Tunguss Traps give an almost identical age of 250 Ma, thus implying a synchronous interregional volcanic even t. There are a few palaeomagnetic transforms within the PTB strata. Th us, multidisciplinary research of the P/T boundary strata allows subdi vision of this short interval into more than ten intercontinentally co rrelatable parts. Each subdivision averages less than 100 ka in durati on. This may be the highest resolution obtained so far in pre-Cretaceo us rocks. High-frequency Milankovitch-type cyclic deposits within the P/T boundary beds enable correlation of even higher resolution in the Lower Yangtze area. This high resolution is made possible because the P/T transition is a time of saltation and catastrophy in geological hi story. Causality of the aggregation of events merits further investiga tion. (C) 1998 Elsevier Science B.V. All rights reserved.