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This paper is dedicated to a global correlation of marine Permian-Triassic boundary layers on the basis of partially published and original data on the δ 13 C org and δ 13 C carb values of the Suol section (Setorym River, South Verkhoyansk region). The section consists of six carbon isotopic intervals, which are easily distinguishable in the carbon isotopic curves for a series of Permian-Triassic reference sections of Eurasia and Northern America, including paleontologically described sections of Central Iran, Kashmir, and Southern China. This suggests that the Permian-Triassic boundary in the Suol section is close to the carbon isotopic minimum of interval IV. In light of new data, we suggest considering the upper part of the Late Permian Changhsingian Stage and the lower substage of the Early Triassic Induan Stage of Siberia in the volumes of the rank Otoceras concavum zone and the Tompophiceras pascoei and Wordieoceras decipiens zones, respectively. The O. concavum zone of the Verkhoyansk region probably corresponds to the Late Changhsingian Hypophiceras triviale zone of Greenland. The carbon isotopic intervals II, III, IV, and V in the Permian-Triassic boundary layers of the Verkhoyansk region traced in a series of the reference sections of Eurasia correspond, most likely, to intensification of volcanic activity at the end of the Late Changhsingian and to the first massive eruptions of Siberian traps at the end of the Changhsingian and the beginning of the Induan Stages. New data indicate the possible survival of ammonoids of the Otoceratoidea superfamily at the species level after mass extinction of organisms at the end of the Permian.

We have obtained the first detailed [section]13Corg record in Permian-Triassic boundary sediments in deepwater facies in Northeast Asia (Kolyma--Omolon region, Balygychan Basin). Our data show good convergence both with the Setorym River section (South Verkoyansk region), where the Permian-Triassic boundary has been determined approximately, and with a number of other sections of Permian-Triassic boundary sediments in the Boreal and Tethyan Superrealms, in particular, in the Buchanan Lake section in Arctic Canada, the Festningen section on Spitsbergen, the Wadi Shahha section on the Arabian Peninsula, and published sections in the Dolomites.

Pseudomorphoses of calcite after ikite are stellar rosette like spheroid crystal nodules or clusters of up to 10 cm in cross size. These units are considered by many researchers as an indicator of low temperatures in a sedimentation basin (around 0C) [13]. They have repeatedly been found in Mesozoic and Cenozoic deposits of Siberia and the Russian Far East.

Middle Permian Inoceramus-like bivalves of the genera Kolymia Licharew and Cyrtokolymia Astafieva endemic to the East Boreal Biogeographic Realm are considered. Cyrtokolymia, previously regarded by the author as endemics of the Verkhoyansk–Okhotsk Province and including only the type species, are also recorded in the Kolyma–Omolon Province, where they are represented by the endemic species C. bobini sp. nov. An emended diagnosis of the genus Cyrtokolymia is provided. The genus Kolymia comprises about 30 species. The greatest diversity of Kolymia (24 species, 13 of which are endemic) is known from the Verkhoyansk–Okhotsk Province, which is the center of diversification of this genus. The Kolyma–Omolon Province is characterized by 12 species, only three of which are endemic. In other provinces of the East Boreal Realm, only individual members of Kolymia are known. From the Middle Permian of the Omolon Massif, northern Verkhoyansk Region, and Penzhinsky Ridge, the following new species are described: Kolymia posneri Muromzeva, Kusnezov et Biakov, sp. nov., K. pontoneica Biakov, sp. nov., K. simkiniformis Biakov, sp. nov., and Cyrtokolymia bobini Biakov, sp. nov.

The biogeography of Permian marine bivalves of the Boreal Superrealm is considered. Two biochores, the Western Boreal and Eastern Boreal realms, divided into a number of provinces are distinctly recognized. The Western Boreal Realm, which comprises the East European, West European, Greenland–Canadian, and Spitsbergen provinces, is distinguished by the widespread occurrence of pteriacians, myalinids, mitilids, Pseudomonotis , Cyrtorostra , and Netschajewia . The Eastern Boreal Realm comprises the Pechora, Novaya Zemlya, Taimyr, Verkhoyansk–Okhotsk, Kolyma–Omolon, Mongol–Transbaikalian, and Yukon provinces and is characterized by the widespread occurrence of Inoceramus -like bivalves of the family Kolymiidae and a high proportion of genera with bipolar distribution.

Geographical and stratigraphical ranges of the bipolar nuculanid bivalves of the genus Glyptoleda is considered. In the Boreal Biogeographical Superrealm, Glyptoleda is only known in the eastern (high boreal) part: in the Novaya Zemlya and Verkhoyansk–Okhotsk provinces. Glyptoleda is recorded for the first time in the Kolyma–Omolon Province. Possibly, the appearance of glyptoleds in the northern Eurasian basins was associated with cooling episodes. A new species, Glyptoleda parenica sp. nov., is described from the Kungurian–Roadian beds of the southeastern framing of the Omolon Massif.

The characteristics of the main biotic groups of the Permian marine basins of northeastern Asia are provided. They include nine animal phyla: sarcodines, sponges, cnidarians, arthropods, bryozoans, brachiopods, mollusks, echinoderms, and conodonts. The distribution of the fauna was nonuniform and controlled primarily by the depth of their habitats. Dominating groups were foraminifers, brachiopods, bivalves, and gastropods. The most diverse fauna inhabited the Omolon Basin, where almost all the above groups have been recorded. A distinctive feature of the Permian biota of northeastern Asia is wide distribution of bipolar taxa in all faunal groups.

Beds with ammonoids are recognized as a result of the study of goniatitids and prolecanitids from the Nyut, Khuren, and Ayan-Yuryakh in the Okhotsk Region. Beds with Neopronorites tenkensis , assigned to the Upper Artinskian Substage, correspond to the upper part of the Echian Horizon of the Verkhoyansk Region. Beds with Paragastrioceras–Baraioceras characterize the middle part of the Kungurian Stage and correlate with the upper sunhorizon of the Tumarian Horizon of the Verkhoyansk Region. Beds with Sverdrupites harkeri correspond to a biostratigraphic subdivision with the same name widely distributed in the Vekhoyansk-Kolyma Region and assigned to the Roadian Stage. The new species Neopronorites tenkensis is described.

The first results are presented for U-Pb SHRIMP-II dating of zircons from the upper part of the Khivachian regional horizon (stage) of the Regional Stratigraphic Scale (RSS) of the Permian in northeastern Russia. The obtained isotope age of 255 [+ or -] 2 Ma is close to that of the present boundary between the Wuchiapingian and Changhsingian stages of the Permian system in the International Stratigraphic Scale (254.1 Ma). Based on the distribution of bivalves–Intomodesma spp. and Claraioides aff.primitivus (Yin)–in the sections considered, their relations to the stratigraphic positions of the samples considered and dated formerly, and in view of the interregional correlation of recent [[delta].sup.13][C.sub.org] data for clayey rocks, one may assume with certainty that most of the regional zone of Intomodesma costatum corresponds to the upper part of the Wuchiapingian stage. Here, the Changhsingian stage in northeastern Asia complies only with the uppermost part of this zone within the I. postevenicum subzone and, partially, of Otoceras layers within the Otoceras concavum zone.

The most ancient representative of Permian Inoceramus -like bivalves, Aphanaia kletzi sp. nov., from the Upper Sakmarian of the Western Verkhoyansk Region (northeastern Asia) is described. It is established for the first time that the first kolymiids appeared in the northeastern Asian basins in the latter half of the Sakmarian rather than at the end of the Artinskian. The age of the record is reliably dated by the ammonoid genera Uraloceras and Neoshumardites .