The Permian of the Verkhoyansk–Okhotsk region, NE Russia Alexander G. Klets a, * , Igor V. Budnikov b , Ruslan V. Kutygin c , Alexander S. Biakov d , Vitaliy S. Grinenko e a Department of Paleontology and Stratigraphy, Institute of Petroleum Geology, Siberian Branch of the Russian Academy of Sciences, Koptyug pr. 3, 630090 Novosibirsk, Russian Federation b Siberian Research Institute of Geology, Geophysics and Mineral Resources, Krasnyi pr 67, Novosibirsk, 630104 Russian Federation c Institute of Diamond and Precious Metals Geology, Yakut Scientific Center, Siberian Branch of the Russian Academy of Sciences, Lenina pr. 39, Yakutsk, 677891 Russian Federation d North-Eastern Complex Research Institute, Far Eastern Branch of the Russian Academy of Sciences, ul. Portovaya 16, Magadan, 685000 Russian Federation e State Unitary Enterprise ‘Yakut Prospecting and Mapping Expedition’, ul. Kalvitsa 24, Yakutsk, 677891 Russian Federation Received 22 October 2004; received in revised form 1 June 2005; accepted 14 October 2005 Abstract This report summarizes data on the Permian deposits of the Verkhoyansk–Okhotsk region (tectonics, paleogeography, fauna, flora and stratigraphy). The Verkhoyansk–Okhotsk region covers the area of the Verkhoyansk fold-and-thrust belt. The Permian deposits of this region were formed on the passive continental margin of the Angarida Continent, the ancient Siberian Continent, situated within the Siberian Platform. This continental margin developed as the result of continental break-up in the Late Precambrian. Late Precambrian to Jurassic (including Permian) sediments were deposited on a passive margin with a continental shelf extending out into an ocean towards the northeast. During the Permian, exclusively terrigenous sediments were deposited over a vast territory in the Verkhoyansk paleobasin forming part of this continental margin. The Permian deposits are divided into six regional stratigraphic units ranked as horizons (Zregional stages), which in turn are subdivided into faunal zones and beds serving as the basis for intra-regional correlation. In the Late Jurassic–Cretaceous the continental margin sediments were converted into a foreland fold-and-thrust belt due to the collision of the Siberian Platform with the Kolyma–Omolon and Okhotsk continental blocks. q 2005 Elsevier Ltd. All rights reserved. Keywords: Permian; Verkhoyansk–Okhotsk region; Stratigraphy; Biostratigraphy; Brachiopods; Ammonoids; Bivalve; Angarida continent 1. Introduction The Permian rock succession in the Verkhoyansk–Okhotsk region attracts considerable interest because it represents a continuous, stratigraphically complete, and well-exposed section with a simple geological structure. The Permian sections are composed predominantly of marine facies that yield goniatites, brachiopods, and bivalves. Regional strati- graphic units are unambiguously correlated with stages of the East European Permian timescale. The Verkhoyansk–Okhotsk region is the key region for solving the main stratigraphic problems of Permian of Siberia. 2. Outline of the geologic structure The Verkhoyansk–Okhotsk region lies in the Lena–Yana drainage basin covering the N–S Verkhoyansk fold-and-thrust belt. The Permian deposits of this region were formed on the passive continental margin of the Angarida (or Siberian) Continent which had developed by continental break-up in the Late Precambrian. Late Precambrian to Jurassic (including Permian) sediments formed a continental shelf extending out into an ocean towards the northeast. The Kolyma–Omolon Superterrane and the Okhotsk Terrane lay on the eastern side of this ocean. Sometime during the Jurassic this ocean began to close by subduction under the Kolyma–Omolon Superterrane and the Okhotsk Terrane. In the Cretaceous these terranes collided with the eastern margin of the Angarida Continent and the continental margin sediments (including the Permian) were thrust westwards over the margin of the Angarida Continent. Journal of Asian Earth Sciences 26 (2006) 258–268 www.elsevier.com/locate/jaes 1367-9120/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.jseaes.2005.10.001 * Corresponding author. Tel.: C7 383 333 24 31; fax: C7 383 333 23 01. E-mail address: kletzag@uiggm.nsc.ru (A.G. Klets).