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New Paleomagnetic Data on Late Cretaceous Chukotka Volcanics: the Chukotka Block Probably Underwent Displacements Relative to the North American and Eurasian Plates after the Formation of the Okhotsk-Chukotka Volcanic Belt?

Authors
  • Lebedev, I. E.1, 2
  • Tikhomirov, P. L.1
  • Pasenko, A. M.1
  • Eid, B.3
  • Lhuillier, F.3
  • Pavlov, V. E.1, 4
  • 1 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, 123242, Russia , Moscow (Russia)
  • 2 Faculty of Geology, Moscow State University, Moscow, 119991, Russia , Moscow (Russia)
  • 3 Department of Earth and Environmental Sciences, Ludwig Maximilian University, Munich, 80539, Germany , Munich (Germany)
  • 4 Kazan (Volga) Federal University, Kazan, 420008, Russia , Kazan (Russia)
Type
Published Article
Journal
Izvestiya, Physics of the Solid Earth
Publisher
Pleiades Publishing
Publication Date
Mar 01, 2021
Volume
57
Issue
2
Pages
232–246
Identifiers
DOI: 10.1134/S1069351321020014
Source
Springer Nature
Keywords
License
Yellow

Abstract

Abstract—Paleomagnetic studies of several Late Cretaceous volcanic sections of the Okhotsk–Chukotka volcanic belt have been carried out in the Bilibino region of the Chukotka Autonomous Okrug and along the Pevek–Egvekenot road. Extensive collections have been acquired and analyzed. The laboratory experiments isolated the ancient characteristic magnetization component reflecting the direction of the geomagnetic field at the time of formation of the studied rocks (~85 Ma ago). The primary character of the revealed characteristic magnetization component is supported by the positive regional fold test and by the coincidence of the paleomagnetic pole calculated from this component with that previously obtained for Chukotka from the rocks of similar age (Stone et al., 2009). The paleomagnetic pole calculated from the combination of the previous and our newly obtained data (Plat = 69.3°, Plong = 180.7°, N = 99, A95 = 5.1°) indicates that the sampled rocks were formed in the immediate vicinity of the geographic pole. The reliability of the existing Late Cretaceous paleomagnetic poles for Eurasia and North America is analyzed, and the refined poles are calculated for these plates for the time of ~85 Ma. The reconstruction of the Chukotka–Kolyma–Omolon block’s position relative to Eurasia and North America allowing for the paleomagnetic poles calculated for that time is proposed. The reconstruction implies that from the formation time of the studied rocks up to the present, the Chukotka–Kolyma–Omolon block has undergone relatively small (tens to first hundreds of km) southward movements relative to the North American plate and has been noticeably shifted (by a few hundred km) relative to the Eurasian plate. Our reconstruction is close to that proposed in (Otofuji et al., 2015) but, in contrast to the latter, it does not require a collision between the Chukotka–Kolyma–Omolon block and Eurasia after 80 Ma ago.

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