Phanerozoic Tectonic Phanerozoic Tectonic Evolution of the Evolution of the

Chukotka-Arctic Alaska Chukotka-Arctic Alaska Block: Problems of the Block: Problems of the

Rotational ModelRotational ModelBoris A. Natal’inBoris A. Natal’in

Istanbul Technical UniversityIstanbul Technical University

Components of the Components of the Chukotka-Arctic Alaska Chukotka-Arctic Alaska

blockblock

Arctic Alaska Arctic Alaska superterranesuperterrane

Seward TerraneSeward Terrane York Mountains York Mountains

terraneterrane

Bennett-Barrovia Bennett-Barrovia blockblock

Chukotka fold beltChukotka fold belt Nutesyn arcNutesyn arc

The Bennett-Barrovia block continues to The Bennett-Barrovia block continues to Alaska as the Hammond subterrane, York Alaska as the Hammond subterrane, York Mountains terrane, and Nixon Fork terraneMountains terrane, and Nixon Fork terrane

AlaskaAlaska ChukotkaChukotka

Proposed Boundaries

of ArcticAlaska-

Chukotka Plate

(dotted line)

Late Jurassic, Late Jurassic, 150 Ma150 Ma

Lawver et al. Lawver et al. 20022002

1000 1000 kmkm

KotelnKotelnyiyi

SevernSevernayaaya

ZemlyaZemlya

KotelnKotelnyiyi

Bol. LyakhovskyBol. Lyakhovsky

122±7 K-122±7 K-ArAr

Younger than late Younger than late JurassicJurassic

291±62 Sm-291±62 Sm-NdNd133-139 Ma 133-139 Ma K-ArK-Ar

Gravity gradientsGravity gradients

Pushkarev et al., 1999

Geophysical dataGeophysical dataFranke et al. Franke et al. (2004): (2004): - Blagoveschensk - Blagoveschensk basin is absentbasin is absent- the shelf of the - the shelf of the East Siberian Sea East Siberian Sea is epicontinental is epicontinental platformplatformPuskarev et al. Puskarev et al. (1999):(1999):- Low standing - Low standing basementbasement- Densities are - Densities are characteristic for characteristic for consolidated crustconsolidated crust

Puskarev et al., 1999Puskarev et al., 1999

SS NN

Bennett-Barrovia block: Bennett-Barrovia block: BasementBasement

Granites 750 MaGranites 750 MaMetamorphism 655-Metamorphism 655-594 Ma594 Ma

GraniteGranitess

699 Ma699 Ma

GranitGraniteses

705 705 MaMa

OrthogneissOrthogneiss681 and 676 681 and 676

MaMa

OrthogneisOrthogneisss

650 Ma650 Ma

Correlation with TaimyrCorrelation with Taimyr Bennett-BarroviaBennett-Barrovia

pre-collision pre-collision volcanics – 633±25 volcanics – 633±25 MaMasyncollisional granites syncollisional granites – 750-699 (650?) Ma – 750-699 (650?) Ma metamorphism – 630 metamorphism – 630 MaMaassimilated crust – assimilated crust – 1.3-1.5 Ga (Nelson et 1.3-1.5 Ga (Nelson et al., 1989) and 0,8-1.0 al., 1989) and 0,8-1.0 (Karl et al., 1989)(Karl et al., 1989)Devonian granites – Devonian granites – 0.7-1.6 Ga0.7-1.6 Ga

TaimyrTaimyrpre-collision pre-collision volcanics – 630-615 volcanics – 630-615 MaMasyncollisional syncollisional granites – 630 Magranites – 630 Mametamorphism – metamorphism – 655-594655-594assimilated crust – assimilated crust – 0.84-1.1 Ga0.84-1.1 Ga

11

22

33

44

55

66

Correlation of Paleozoic Correlation of Paleozoic sectionssections

Barrovia (Sherwood, 1992)Barrovia (Sherwood, 1992)

Taimyr and Severnaya Zemlya Taimyr and Severnaya Zemlya (Russia)(Russia)

Thick pile of the Thick pile of the upper Proterozoic-upper Proterozoic-Cambrian flyschCambrian flysch

Evaporites in the Evaporites in the Ordovician and Ordovician and Upper Silurian and Upper Silurian and DevonianDevonian

Early Paleozoic Early Paleozoic fossils are differentfossils are different

Franklinian structuresFranklinian structures

sandstone, sandstone, tuffaceous tuffaceous sandstone, sandstone, shale, shale, conglomerate, conglomerate, lavas and dikes lavas and dikes of basalt, of basalt, andesite, and andesite, and diabase diabase

Ordovician Ordovician to Silurian to Silurian oceanic oceanic and and magmatic magmatic arc rock arc rock assemblageassemblagess

Margin of N. America

Deformed Deformed Ordovician Ordovician and Silurian and Silurian slatesslates

Pre-late Devonian subduction Pre-late Devonian subduction related magmatic arc at the related magmatic arc at the

eastern edge of BBeastern edge of BBgravitgravityy

magnemagnetictic

Herman and Herman and Zerwick, 1998Zerwick, 1998

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

Devonian-early Carboniferous Devonian-early Carboniferous subduction zone along the southern subduction zone along the southern

margin of the Bennett-Barrovia blockmargin of the Bennett-Barrovia block

398-383 398-383 MaMaeuhedraeuhedral zircons l zircons of 370-of 370-360 Ma360 Ma

381 381 MaMa 375 ± 11 375 ± 11

MaMa376 ± 37 376 ± 37 MaMa

εεNdNd is is +0.2 and +0.2 and -0.3-0.3

360 360 Ma Ma

ViseaViseann

Back arc basin of the Back arc basin of the Devonian arcDevonian arc

Tanatap basin- deep water shale and fine grained turbidite- high-K andesitic tuffs with εεNdNd -7 -7

Alyarmaut Alyarmaut - Calc-silicates, quartzite, mafic tuffs- Calc-silicates, quartzite, mafic tuffs

Belkovskyi-Nerpalakh Trough Belkovskyi-Nerpalakh Trough - Upper Devonian to Lower Carboniferous - Upper Devonian to Lower Carboniferous limestone, shale, sandstone, limestone, shale, sandstone, conglomerate, mafic dikes and sills conglomerate, mafic dikes and sills

Brooks RangeBrooks Range- Devonian extensional basin (the - Devonian extensional basin (the Beaucoup F.) Beaucoup F.)

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

Carboniferous-PermianCarboniferous-Permian

Wrangel IslandWrangel Island- shallow marine Carboniferous limestones - shallow marine Carboniferous limestones grading up into Permian slates 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

Modified after Grantz et al. (1991)

4.5 4.5 kmkm

molasmolassese

orogeorogenyny

Many kmMany kmlithic lithic turbiditeturbiditemafic mafic magmatismagmatismmriftingrifting

0.1-0.2 km0.1-0.2 kmshale, shale, chert, chert, sandstonesandstonestable stable shelfshelf

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

Opening of Opening of the South the South

Anyui Anyui oceanocean

Position of continents is after Lawver et al. (2002)