Ophiolitic Complex of the Matachingai River on Eastern Chukotka: Fragment of Lithosphere in Mesozoic Back-Arc Basin
- Authors: Ledneva G.V.1, Bazylev B.A.2, Moiseev A.V.1, Sokolov S.D.1, Ishiwatari A.3, Kuzmin D.V.4, Belyatsky B.V.5
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Affiliations:
- Geological Institute
- Vernadsky Institute of Geochemistry and Analytical Chemistry
- Nuclear Regulation Authority
- Sobolev Institute of Geology and Mineralogy, Siberian Branch
- Center for Isotope Research
- Issue: Vol 52, No 4 (2018)
- Pages: 447-467
- Section: Article
- URL: https://journals.rcsi.science/0016-8521/article/view/156715
- DOI: https://doi.org/10.1134/S0016852118040040
- ID: 156715
Cite item
Abstract
The Matachingai River basin is known among the few ophiolitic complexes on eastern Chukotka as the southern boundary of the Chukotka Fold System (in terms of tectonics, the Chukotka microcontinent or a fragment of the Arctic Alaska–Chukotka microplate). This complex comprises tectonic blocks of residual spinel harzburgite with dunite bodies and pyroxenite, olivine gabbro, and leucogabbro veins; blocks of hornblende gabbro, diorite, and plagiogranite; and Upper Jurassic–Lower Cretaceous basaltic–cherty and cherty–carbonate rocks. The geological relationships of rocks within tectonic blocks, the compositions of primary minerals, the bulk geochemistry of rocks, as well as the strontium, neodymium, and lead isotopic compositions, make it possible to consider individual tectonic blocks of the complex as fragments of a disintegrated oceanic-type lithosphere that formed in a back-arc spreading center. The melts, crystallization products of which are represented by hornblende gabbro of blocks, olivine gabbro of veins, and basalts, separated from geochemically and isotopically heterogeneous mantle. Blocks composed of rocks with various modal composition are likely relicts of an oceanic lithosphere of different segments of a back-arc basin. The studied complex may be a lithosphere of one of the Middle–Late Jurassic back-arc basins. Fragments of these basins are retained in ophiolitic complexes on Great Lyakhovsky Island of the New Siberian Islands Archipelago, western Chukotka, and the Brooks Range in Alaska.
About the authors
G. V. Ledneva
Geological Institute
Author for correspondence.
Email: ledneva@ilran.ru
Russian Federation, Moscow, 119017
B. A. Bazylev
Vernadsky Institute of Geochemistry and Analytical Chemistry
Email: ledneva@ilran.ru
Russian Federation, Moscow, 119991
A. V. Moiseev
Geological Institute
Email: ledneva@ilran.ru
Russian Federation, Moscow, 119017
S. D. Sokolov
Geological Institute
Email: ledneva@ilran.ru
Russian Federation, Moscow, 119017
A. Ishiwatari
Nuclear Regulation Authority
Email: ledneva@ilran.ru
Japan, Minato-ku, Tokyo, 106-8450
D. V. Kuzmin
Sobolev Institute of Geology and Mineralogy, Siberian Branch
Email: ledneva@ilran.ru
Russian Federation, Novosibirsk, 630090
B. V. Belyatsky
Center for Isotope Research
Email: ledneva@ilran.ru
Russian Federation, St. Petersburg, 199106
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