When considering the problem of determining the Permian–Triassic boundary, one usually uses data on ammonoids, conodonts, bivalves, and, more rarely, brachiopods. Data concerning the character of radiolarian development have not often been used, because representatives of that group are absent from the carbonate-terrigenous deposits of the Permian–Triassic boundary beds in the most representative sections in southeastern China (Yang Zunyi and Li Zishun, 1992), the Transcaucasus (Zakharov, 1992), Iran (Bando, 1979), and the Himalayas (Kapoor, 1992).

Recently, Permian and Triassic Radiolaria from cherty sequences in Japan (Nakaseko and Nishimura, 1979; Caridroit, 1986; Ishiga, 1986, 1990) and Sikhote-Alin (Rudenko and Panasenko, 1990a,b,c; Bragin, 1991; Rudenko, Panasenko, and Rybalka, 1992) have received intensive study. However, a serious obstacle to solving the boundary problem arises because of the absence of radiolarians and conodonts immediately above the Permian–Triassic boundary beds within the discrete cherty plates that are common in the olistostrome terranes of the circum-Pacific.

In Tonishi-type shales in the Ashio Mountains, central Japan, the radiolarian Neoalbaillella is found in Lower Dorashamian grey and dark-grey platy cherts, and conodonts are found in Lower Triassic (Smithian) grey cherty argillites (Yamashita, Ishida, and Ishiga, 1992; Sashida, Kamata, and Igo, 1992). A similar picture is seen in Sikhote-Alin.

Recently, we found Permian Radiolaria on the Pantovyi Creek left bank (Taukha Terrane, Tumanovka River basin, 300 m to the west of Zarod Mountain).