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Paleomagnetism of cretaceous units of the Mametchinskiy Peninsula, Kuyul Region, Northeastern Russia: Implications for development and evolution of the Northwest Pacific Basin

Harbert, W and Alexutin, M and Sokolov, S and Krylov, K and Grigoriev, V and Heiphetz, A and Graham, R (2001) Paleomagnetism of cretaceous units of the Mametchinskiy Peninsula, Kuyul Region, Northeastern Russia: Implications for development and evolution of the Northwest Pacific Basin. Tectonophysics, 340 (3-4). 215 - 231. ISSN 0040-1951

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The northernmost part of the Kamchatka Peninsula of northeastern Russia, located along the northwestern margin of the Bering Sea, consists of zones of complexly deformed accreted terranes. Progressing from the northwestern Bering Sea inland are the Olyutorskiy, Ukelayat, and Koryak superterranes, which were accreted to the Okhotsk-Chukotsk volcanic-plutonic belt (OChVB) during the Campanian-Maastrichtian (Koryak) to Middle Eocene (Olyutorskiy), respectively. To constrain the accretion paleolatitude of the Koryak superterrane, we paleomagnetically sampled a sedimentary series on the Mametchinskiy Peninsula. At the Mametchinskiy Peninsula, in the northeastern Penzhinskaya Guba (61.45° N, 163.75° E), a gently deformed, well-bedded section of fine-grained Lower to lower Upper Cretaceous turbidites, the Mametchinskaya and Tylakrylskaya Formations are exposed. These strata, which represent the lower part of the sedimentary cover of the terranes in this region and the forearc of OChVB, were sampled at 39 sites (three to seven samples per site). Within the Ainyn terrane, more than 1000 m of section of Cenomanian-Turonian age was sampled at a basal locality (sample groups I and II, sites 1-18, 19-29) and at an upper locality of Valanginian- Barremian age (sample group III, sites 30-39) along the western shore of the Peninsula. Thermal demagnetization and principal component analysis of the demagnetization data show lower-temperature (A) and higher-temperature (B) magnetic components. Although group III samples did not display a coherent A component, the A component of group I and II samples was observed as a single-polarity lower-unblocking temperature component generally removed by 100- 400°C. This component failed the fold test at the 95% confidence level. With respect to direction, the A component is similar to both the present-day field and axial-geocentric dipole directions expected at this site. The B component was observed during thermal demagnetization steps up to 580 °C and was always of downward-directed inclination. Coherence of bedding corrections within each section do not allow statistically meaningful fold tests within groups I, II or III. Assuming the B component represents a Cretaceous magnetization, two overall models are proposed. In the first model (preferred), with the highest clustering of directions (k-value=36.7, N (sites) = 36), indicates significant poleward motion of the Ainyn terrane (observed paleolatitude λM1=61.0±6.5°; expected North America plate reference site paleolatitude λE=74.0±3.5°). In the second model, no significant poleward displacement is implied (λM2=72.0±9.6). © 2001 Elsevier Science B.V. All rights reserved.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Harbert, Wharbert@pitt.eduHARBERT
Alexutin, M
Sokolov, S
Krylov, K
Grigoriev, V
Heiphetz, A
Graham, R
Date: 8 December 2001
Date Type: Publication
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Journal or Publication Title: Tectonophysics
Volume: 340
Number: 3-4
Page Range: 215 - 231
DOI or Unique Handle: 10.1016/s0040-1951(01)00177-9
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Refereed: Yes
ISSN: 0040-1951
Date Deposited: 26 Aug 2012 14:00
Last Modified: 22 Jun 2021 12:56


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