Title: Phanerozoic Tectonic Evolution of the ChukotkaArctic Alaska Block: Problems of the Rotational Model
1Phanerozoic Tectonic Evolution of the
Chukotka-Arctic Alaska Block Problems of the
Rotational Model
- Boris A. Natalin
- Istanbul Technical University
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3Components 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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5Proposed Boundaries of Arctic Alaska- Chukotka
Plate (dotted line)
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7Late Jurassic, 150 MaLawver et al. 2002
8Bol. Lyakhovsky
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10Gravity gradients
Pushkarev et al., 1999
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15Geophysical 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
16Bennett-Barrovia block Basement
17Correlation 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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19Correlation of Paleozoic sections
20Barrovia (Sherwood, 1992)
21Taimyr 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
22Franklinian structures
23Pre-late Devonian subduction related magmatic arc
at the eastern edge of BB
gravity
magnetic
Herman and Zerwick, 1998
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26The late Silurian-early Devonian collision of the
Bennett-Barrovia block
27Devonian-early Carboniferous subduction zone
along the southern margin of the Bennett-Barrovia
block
28Back 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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30Position of continents is after Lawver et al.
(2002) 390 Ma
31Carboniferous-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
32Modified after Grantz et al. (1991)
33Carboniferous collision?
Position of continents is after Lawver et al.
(2002) 330 Ma
34Opening of the South Anyui ocean
Position of continents is after Lawver et al.
(2002)
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