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Deformational history and thermochronology of Wrangel Island, East Siberian Shelf and coastal Chukotka, Arctic Russia

Miller, Elizabeth L. ; Akinin, V. V. ; Dumitru, T. A. ; Gottlieb, E. S. ; Grove, M. ; Meisling, K. ; Seward, G.

Circum-Arctic Lithosphere Evolution, 2018-01, Vol.460 (1), p.207-238 [Periódico revisado por pares]

London: The Geological Society of London

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  • Título:
    Deformational history and thermochronology of Wrangel Island, East Siberian Shelf and coastal Chukotka, Arctic Russia
  • Autor: Miller, Elizabeth L. ; Akinin, V. V. ; Dumitru, T. A. ; Gottlieb, E. S. ; Grove, M. ; Meisling, K. ; Seward, G.
  • É parte de: Circum-Arctic Lithosphere Evolution, 2018-01, Vol.460 (1), p.207-238
  • Descrição: In Arctic Russia, south of Wrangel Island, Jura-Cretaceous fold belt structures are cut by c. 108-100 Ma plutonic rocks and a c. 103 Ma migmatitic complex (U-Pb, zircon) that cooled by c. 96 Ma (40Ar/39Ar biotite); the structures are unconformably overlain by c. 88 Ma and younger (U-Pb, zircon) volcanic rocks. Wrangel Island, with a similar stratigraphy and added exposure of Neoproterozoic basement rocks, was thought to represent the westwards continuation of the Jura-Cretaceous Brookian thrust belt of Alaska. A penetrative, high-strain, S-dipping foliation formed during north-south stretching in Triassic and older rocks, with stretched pebble aspect ratios of c. 2:1:0.5 to 10:1:0.1. Deformation was at greenschist facies (chlorite+white mica; biotite at depth; temperature c. 300-450°C). Microstructures suggest deformation mostly by pure shear and north-south stretching; the quartz textures and lattice preferred orientations suggest temperatures of c. 300-450°C. 40Ar/39Ar K-feldspar spectra (n=1) and muscovite (n=3) (total gas ages c. 611-514 Ma) in Neoproterozoic basement rocks are consistent with a short thermal pulse during deformation at 105-100 Ma. Apatite fission track ages (n=7) indicate cooling to near-surface conditions at c. 95 Ma. The shared thermal histories of Wrangel Island and Chukotka suggest that Wrangel deformation is related to post-shortening, north-south extension, not to fold-thrust belt deformation. Seismic data (line AR-5) indicate a sharp Moho and strong sub-horizontal reflectivity in the lower and middle crust beneath the region. Wrangel Island probably represents a crustal-scale extensional boudin between the North Chukchi and Longa basins.
  • Editor: London: The Geological Society of London
  • Idioma: Inglês
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