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Russian Geology and Geophysics 58 (2017) 1001–1017 www.elsevier.com/locate/rgg

Geology and paleomagnetism of Jeannette Island (De Long Archipelago, Eastern Arctic)

A.I. Chernova a,b,*, D.V. Metelkin b,a, N.Yu. Matushkin a,b, V.A. Vernikovsky a,b, A.V. Travin a,b,c

a A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia b Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia c V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia d Tomsk State University, Tomsk, pr. Lenina, 36, 634050, Russia

Received 14 February 2017; accepted 11 March 2017

Abstract

New characteristics and generalized geostructural, isotope-geochronological, and paleomagnetic data are presented for the first time for the territory of Jeannette Island in the De Long Archipelago. Until recently, this small rock outcrop in the East Siberian Sea, discovered in the late 19th century, has been in effect a blank spot on the geological map. Field work made in 2013 and subsequent laboratory analysis of the obtained sample collection show that the island has a volcanogenic-sedimentary section including many thin (up to several meters) dolerite dikes. These dikes are the main target of the study. Newly obtained 40Ar/39Ar isotope-geochronological data indicate that the earliest dike intrusion stage corresponds to the Ediacaran (553.6 ± 10.3 Ma). Several subsequent tectonothermal events can be inferred until and through the Early Carboniferous, which affected the stability of the isotope system in the dolerites. In addition, paleomagnetic data confirm at least one more stage of dike emplacement, in the Early Ordovician, as the coordinates of the virtual geomagnetic poles for the dikes are nearly identical to those of the Ordovician paleomagnetic pole determined for carbonate rocks of Kotelny Island. The study describes the main petromagnetic characteristics and magnetic mineralogy of the studied dolerites, validating the primary thermoremanent nature of the identified characteristic component. The results agree with available information on the paleomagnetism, tectonics, and paleogeography of the New Siberian Islands. © 2017, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Keywords: paleomagnetism; isotope geochronology; Jeannette Island; De Long Archipelago; New Siberian Islands; Arctic

Introduction recent years an active effort of geological and geophysical investigations of the territory of the islands and the adjacent The geology of the Eastern Arctic shelf is one of the most shelf is underway. There have been successes in unraveling topical issues both for fundamental science and for the the tectonic evolution and the geology of these structures and achievement of specific goals, including geopolitical applica- in constructing more substantiated geodynamic models (Fila- tions (Dobretsov and Kontorovich, 2013; Laverov et al., 2013; tova and Khain, 2010; Korago et al., 2014; Koulakov et al., Lobkovsky et al., 2011). The De Long group of islands in the 2013; Lobkovsky, 2016; Miller et al., 2006; Pyatkova et al., far northeast of the New Siberian Islands Archipelago is one 2015; Vernikovsky et al., 2013a). Objective difficulties in of the few sites available for direct geological studies in this doing research in this region are mainly due to its extreme region. The De Long Islands include five small island uplifts: isolation and hard climatic conditions, so geological routes can Bennett, Zhokhov, Vilkitsky, Henrietta, and Jeannette. Most only be performed in narrow time intervals. Difficulty is added of them remain the least studied in the New Siberian Islands by the small size of the islands themselves and the limited Archipelago and in the Eastern Arctic in general, although in number of accessible research targets. The least studied among these islands is Jeannette Island. It was discovered in 1881 * Corresponding author. during the expedition of American polar explorer George E-mail address: [email protected] (A.I. Chernova) Washington De Long. Until recently the island was in effect 1068-7971/$ - see front matter D 2017, V S..S bolevo IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.rgg.2017.08.001 1002 A.I. Chernova et al. / Russian Geology and Geophysics 58 (2017) 1001–1017