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U–Pb zircon geochronology of Cretaceous arc magmatism in eastern Chukotka, NE Russia, with implications for Pacific plate subduction and the opening of the Amerasia Basin

By
Victoria Pease
Victoria Pease
1
Department of Geological Sciences, Stockholm University, Stockholm, Sweden
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Elizabeth Miller
Elizabeth Miller
2
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA
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Sandra J. Wyld
Sandra J. Wyld
3
MapTect LLC, Athens, GA 30606, USA
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Sergey Sokolov
Sergey Sokolov
4
Geological Institute, Russian Academy of Sciences, Moscow 119017, Russia
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Viacheslav Akinin
Viacheslav Akinin
5
North East Interdisciplinary Science Research Institute, Russian Academy of Sciences, Magadan, Russia
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James E. Wright
James E. Wright
6
Department of Geology, University of Georgia, Athens, GA 30602, USA
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Published:
January 01, 2018

Abstract

The tectonomagmatic evolution of eastern Chukotka, NE Russia, is important for refining the onset of Pacific plate subduction, understanding the development of the Amerasia Basin, and constraining Arctic tectonic reconstructions. Field mapping and strategic sample collection provide relative age constraints on subduction-related continental arc magmatism in eastern Chukotka. Ion microprobe U–Pb zircon ages provide absolute constraints and identify five magmatic episodes (c. 134, 122, 105, 94 and 85 Ma) separated by three periods of uplift and erosion (c. 122–105, 94–85 and post-85 Ma). Volcanic rocks in the region are less contaminated than their plutonic equivalents which record greater crustal assimilation. These data, combined with xenocrystic zircons, reflect the self-assimilation of a continental arc during its evolution. Proto-Pacific subduction initiated by c. 121 Ma and arc development occurred over c. 35–50 myr. Crustal growth was simultaneous with regional exhumation and crustal thinning across the Bering Strait region. Ocean–continent subduction in eastern Chukotka ended at c. 85 Ma. The timing of events in the region is roughly synchronous with the inferred opening of the Amerasia Basin. Simultaneous arc magmatism, extension and development of the Amerasia Basin within a back-arc basin setting best explain these coeval tectonic events.

Supplementary material: Includes SIMS U–Pb and geochemistry data tables, detailed geological map and geochemical figures which are available at https://doi.org/10.6084/m9.figshare.c.3784565

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Contents

Geological Society, London, Special Publications

Circum-Arctic Lithosphere Evolution

V. Pease
V. Pease
Stockholm University, Sweden
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B. Coakley
B. Coakley
University of Alaska, Fairbanks, USA
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The Geological Society of London
Volume
460
ISBN electronic:
9781786203410
Publication date:
January 01, 2018

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