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Russian Geology and Geophysics

2017 year, number 9


A.I. Chernova1,2, D.V. Metelkin2,1, N.Yu. Matushkin1,2, V.A. Vernikovsky1,2, A.V. Travin3,2,4
1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4Tomsk State University, Tomsk, pr. Lenina, 36, 634050, Russia
Keywords: Paleomagnetism, isotope geochronology, Jeannette Island, De Long Archipelago, New Siberian Islands, Arctic


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 volcanosedimentary 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.