WAS PALAEO-TETHYS THE MOST EFFECTIVE KILLER IN EARTH HISTORY?

The end-Permian extinction is the largest known from the geological record. Proposed causes range from bolide impact, through Pangaea formation, pronounced regression and increased continentality, vast plateau basalt eruptions, ocean-wide anoxia plus oceanic gas eruption(s) and global warming or cooling, or any combination of these. Any proposed mechanism, or combination of mechanisms, has to be unique, however, because the magnitude of the event(s) was unique in earth history and, notwithstanding its uniqueness, it has to be testable. None of the mechanisms so far proposed has been unique to the Permian in kind, although their magnitudes and/or effects have been claimed to have been so. We here propose a Ptolemaic earth model, i.e. one with two non-communicating oceans: Palaeo-Tethys and Panthalassa. Palaeo-Tethys was sealed off from Panthalassa by a land bridge formed from the Cimmerian Continent, the Cathaysian and the Manchuride orogenic collages and the Tuva-Mongol Fragment of the eastern Altaids. Late Permian water exchange between Palaeo-Tethys and Panthalassa and Palaeo-Tethys and the opening Neo-Tethyan rifts was very limited and confined to shallow water corridors with three narrow exceptions. Thus sealed off, anoxia began in Palaeo-Tethys locally already in the late Carboniferous and spread rapidly in the Permian. We suggest that heating of an equtorial closed ocean by local forced downwelling led to deep water hyperthermia and consequent oceanic gas eruptions that created a killing halo around Palaeo-Tethys with a width of 2000 km as indicated by the distribution of fungal spike reports concurrently with vast spills of anoxic waters into Panthalassa. Because a Ptolemaic condition has so far occured only once in earth history, this mechanism is unique and has testable consequences.