WORLDWIDE END PERMIAN TSUNAMIS: THEIR DEPOSITS AND GENESIS

At least three coarse intrabioclastic limestones at the base of the Khunamuh Formation (latest Permian) in Kashmir show features typical features of wave reworking of sediments too deep to be affected by storm waves. These are now interpreted as the deposits of large tsunamis by inferring the wavelengths and amplitudes of the waves from basic wave theory. The same three beds are found in latest Permian shallow marine to moderately deep slope environments throughout the southern Neotethy, as well as further afield in the Alps, East Greenland, and possibly even in the lowland deposits of the European Buntsandstein. Such tsunamis can also account for the contemporary marine erosion surfaces in China and elsewhere in shelf and slope environments. Tsunami waves, unlike storm waves, can also cause reworking of fine sediment and ventilation in deep-sea deposits, and there is some evidence for this in latest Permian oceanic sediments in Japan, New Zealand and western North America. The inferred huge size of the tsunami waves requires marine extraterrestrial impacts or large slumps into and/or under the sea, to generate them. The lack of good evidence for marine extraterrestrial impacts in the latest Permian, and the presence of seismically disturbed beds below the tsunami deposits in some sections suggest that large earthquakes preceded the formation of the tsunamis. These earthquakes might have triggered tsunami-generating large submarine landslides, such as are seen in Quaternary deposits at continental margins and around the Hawaiian and other oceanic volcanic islands. Large slumps of the appropriate age occur in some latest Permian sections in East Greenland and New Zealand.