The deep-water successions in Japan, Sikhote-Alin, and Nevada demonstrate a
sharply decreased silica productivity across the Permian-Triassic boundary
, accumulation of carbonaceous shales, and virtually absolute absence of fo
ssil radiolarians and sponges. In Japanese sections, this stratigraphic lev
el is enriched in titanium, phosphorus, and yttrium, and also demonstrate a
sharp decline in cerium content relative to other rare-earth elements. The
se phenomena are directly or indirectly related to the biotic crisis at the
Permian-Triassic boundary. The geochemical anomalies are interpreted as re
lated to significant environmental changes in response to intense tectonic
activity. The changes caused extinction of many marine biotic groups, inclu
ding siliceous plankton, and increased the primary productivity of lower ph
ytoplankton taxa. The event in question differs from the Mesozoic anoxic ep
isodes in its origin, significance, and duration, being followed by the wel
l-manifested biotic crisis.