Boris A. Natal’in Istanbul Technical University

1. Phanerozoic Tectonic Evolution of the Chukotka-Arctic Alaska Block: Problems of the Rotational Model Boris A. Natal’in Istanbul Technical University

3. Arctic Alaska superterrane Seward Terrane York Mountains terrane Bennett-Barrovia block Chukotka fold belt Nutesyn arc Components of the Chukotka-Arctic Alaska block Alaska Chukotka The Bennett-Barrovia block continues to Alaska as the Hammond subterrane, York Mountains terrane, and Nixon Fork terrane

5. Proposed Boundaries of Arctic Alaska- Chukotka Plate (dotted line)

7. 1000 km Kotelnyi SevernayaZemlya Kotelnyi Late Jurassic, 150 MaLawver et al. 2002

8. 291±62 Sm-Nd133-139 Ma K-Ar 122±7 K-Ar Younger than late Jurassic Bol. Lyakhovsky

10. Gravity gradients Pushkarev et al., 1999

15. Geophysical data Puskarev et al., 1999 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 S N

16. Granites699 Ma Granites 750 MaMetamorphism 655-594 Ma Granites705 Ma Orthogneiss650 Ma Orthogneiss681 and 676 Ma Bennett-Barrovia block: Basement

17. Bennett-Barrovia pre-collision volcanics – 633±25 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 Correlation with Taimyr

18. 1 6 2 3 5 4

19. Correlation of Paleozoic sections

20. Barrovia (Sherwood, 1992)

21. 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

22. Margin of N. America sandstone, tuffaceous sandstone, shale, conglomerate, lavas and dikes of basalt, andesite, and diabase Ordovician to Silurian oceanic and magmatic arc rock assemblages Deformed Ordovician and Silurian slates Franklinian structures

23. Pre-late Devonian subduction related magmatic arc at the eastern edge of BB gravity magnetic Herman and Zerwick, 1998

26. The late Silurian-early Devonian collision of the Bennett-Barrovia block

27. 398-383 Maeuhedral zircons of 370-360 Ma Visean 360 Ma 381 Ma 375 ± 11 Ma376 ± 37 MaεNd is +0.2 and -0.3 Devonian-early Carboniferous subduction zone along the southern margin of the Bennett-Barrovia block

28. Back arc basin of the Devonian arc • Tanatap basin- deep water shale and fine grained turbidite- high-K andesitic tuffs withεNd -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.)

30. Position of continents is after Lawver et al. (2002); 390 Ma

31. 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

32. Many kmlithic turbiditemafic magmatismrifting 0.1-0.2 kmshale, chert, sandstonestable shelf 4.5 kmmolasseorogeny Modified after Grantz et al. (1991)

33. Carboniferous collision? Position of continents is after Lawver et al. (2002); 330 Ma

34. Opening of the South Anyui ocean Position of continents is after Lawver et al. (2002)