Phanerozoic Tectonic Evolution of the ChukotkaArctic Alaska Block: Problems of the Rotational Model

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Phanerozoic Tectonic Evolution of the
Chukotka-Arctic Alaska Block Problems of the
Rotational Model

• Boris A. Natalin
• Istanbul Technical University

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Components of the Chukotka-Arctic Alaska block
Alaska
Chukotka

• Arctic Alaska superterrane
• Seward Terrane
• York Mountains terrane

• Bennett-Barrovia block
• Chukotka fold belt
• Nutesyn arc

The Bennett-Barrovia block continues to Alaska as
the Hammond subterrane, York Mountains terrane,
and Nixon Fork terrane
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Proposed Boundaries of Arctic Alaska- Chukotka
Plate (dotted line)
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Late Jurassic, 150 MaLawver et al. 2002
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Bol. Lyakhovsky
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Gravity gradients
Pushkarev et al., 1999
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Geophysical data

• Franke et al. (2004) - Blagoveschensk basin is
  absent- the shelf of the East Siberian Sea is
  epicontinental platform
• Puskarev et al. (1999)
• - Low standing basement- Densities are
  characteristic for consolidated crust

Puskarev et al., 1999
S
N
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Bennett-Barrovia block Basement
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Correlation with Taimyr

• Bennett-Barrovia pre-collision volcanics
  63325 Masyncollisional granites 750-699
  (650?) Ma metamorphism 630 Maassimilated
  crust 1.3-1.5 Ga (Nelson et al., 1989) and
  0,8-1.0 (Karl et al., 1989)Devonian granites
  0.7-1.6 Ga

• Taimyrpre-collision volcanics 630-615
  Masyncollisional granites 630 Mametamorphism
  655-594assimilated crust 0.84-1.1 Ga

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Correlation of Paleozoic sections
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Barrovia (Sherwood, 1992)
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Taimyr and Severnaya Zemlya (Russia)

• Thick pile of the upper Proterozoic-Cambrian
  flysch
• Evaporites in the Ordovician and Upper Silurian
  and Devonian
• Early Paleozoic fossils are different

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Franklinian structures
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Pre-late Devonian subduction related magmatic arc
at the eastern edge of BB
gravity
magnetic
Herman and Zerwick, 1998
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The late Silurian-early Devonian collision of the
Bennett-Barrovia block
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Devonian-early Carboniferous subduction zone
along the southern margin of the Bennett-Barrovia
block
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Back arc basin of the Devonian arc

• Tanatap basin- deep water shale and fine grained
  turbidite- high-K andesitic tuffs with eNd -7
• Alyarmaut - Calc-silicates, quartzite, mafic
  tuffs
• Belkovskyi-Nerpalakh Trough - Upper Devonian to
  Lower Carboniferous limestone, shale, sandstone,
  conglomerate, mafic dikes and sills
• Brooks Range- Devonian extensional basin (the
  Beaucoup F.)

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Position of continents is after Lawver et al.
(2002) 390 Ma
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Carboniferous-Permian

• Wrangel Island- shallow marine Carboniferous
  limestones grading up into Permian slates (2100
  m)- basin slopes to the south
• Chukotka- Lower Carboniferous conglomerates
  grading up into arkose sandstones, shale, and
  limestones (4500 m)- Permian rocks are unknown-
  Source area is expected in the south- Source
  area have to be rich in granites

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Modified after Grantz et al. (1991)
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Carboniferous collision?
Position of continents is after Lawver et al.
(2002) 330 Ma
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Opening of the South Anyui ocean
Position of continents is after Lawver et al.
(2002)
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