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Origin of the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and Geochemistry

Origin of the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and Geochemistry. J. Toro, West Virginia University, USA A.V. Prokopiev, RAS, Yakutsk, Russia E.L. Miller, Stanford University, USA V.A. Trunilina, RAS, Yakutsk, Russia A.G. Bakharev, RAS, Yakutsk, Russia.

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Origin of the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and Geochemistry

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  1. Originof the Main Granitoid Belt of Northeastern Russia: New U-Pb Geochronology and Geochemistry J. Toro, West Virginia University, USA A.V. Prokopiev, RAS, Yakutsk, Russia E.L. Miller, Stanford University, USA V.A. Trunilina, RAS, Yakutsk, Russia A.G. Bakharev, RAS, Yakutsk, Russia

  2. Northern Belt Main Belt Tas-Kystabyt Belt Cretaceous(?) Granites of NE Russia Arctic Ocean Yakutsk Magadan Okhotsk Sea

  3. Kolyma-Omolon superterrane Verkhoyansk Thrust belt Volcanic Belt North Asia Craton (Siberia) Chukotsk Okhotsk- Pacific Ocean Terrain Map after Nokleberg et al. 2001

  4. Aeromagnetics and Granites SouthAnyuiSuture Verkhoyansk

  5. Scotese, Nokleberg et al. 2001

  6. 143-138 Ma 130-123 Ma Scotese, Nokleberg et al. 2001

  7. Tectonic Evolution OimyakonOcean Late Jurassic (Oxf.-Kimm.) 161-151 Ma Kolyma Omolon Microcontinent Siberia 151-145 Ma Late Jurassic (Tithonian) Early Cretaceous 145-100 Ma Parfenov, 1991

  8. Crosssection across Verkhoyansk - Kolymaorogen (after Prokopiev, 1998)

  9. Trace Element Characteristics Collision Within Plate Volcanic Arc Orogenic Granitoid tectonic discrimination diagram (Pearce et al. 1984)

  10. U-Pb Zircon Geochronology • 10 Main Belt Plutons • 4 Northern Belt Plutons • 5 Tas Kystabyt Granites and Sub-volcanics • 2 Uyandina-Yasachnida Volcanics • USGS/STANFORD SHRIMP-RG • At least 10 zircons per sample • Rims and cores

  11. Chersky Range Granites Arctic Ocean Yakutsk Magadan Okhotsk Sea

  12. Main Belt Granites-Chersky Range Pravo-Tuostakh Chibagalakh Chimalga Ar/Ar=131-143 Porozhnotsepinsky Ar/Ar=143 Khayargastakh Pravo Kharaulakh Chuguluk Ust Nera Nelkan 100 km Ar/Ar=144

  13. Main Belt- Chibagalakh 238U/206Pb Ages 151±1.4 154±1.7 147±1.6 155±1.8 200 microns

  14. 238

  15. Main Belt Granites-Chersky Range Pravo-Tuostakh 148-154 Ma Chibagalakh Chimalga 145-155 Ma Porozhnotsepinsky 155±1.4 Ma Khayargastakh 147-156 Ma Pravo Kharaulakh 154±1.2 Ma Chuguluk 151 Ma Ust Nera 84±1 Ma Nelkan 100 km 148±1 Ma, 2 Ga cores

  16. Tas-Kystabyt Belt-Trud Granite

  17. 155-138 Ma

  18. Conclusions • Magmatism in the Main Belt 155-145 Ma • Main Belt Granitoids are coeval with Uyandina-Yasachnida Arc • Main Belt is probably subduction related, not collisional • Subduction under Verkhoyansk Margin during Late Jurassic(?)→ Tas-Kystabyt • Northern Belt is 126-136 Ma

  19. Geologicalmap of the Verkhoyansk-Kolyma orogen

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