1. Tectonic Overview of the Verkhoyansk-Kolyma Orogenic Region Andrei Prokopiev, Diamond and Precious Metal Geology Institute, Yakutsk, Russian Federation Jaime Toro, Dept. of Geology and Geography, West Virginia University, USA The Moma Range, Eastern Yakutia, August 1998 U.S.-Russia Joint Workshop on the Plate Tectonic Evolution of NE Russia STANFORD UNIVERSITY, DECEMBER 9-12, 2004

2. Outline Review of the Verkhoyansk from N to S Kular-Nera Slate Belt Cratonal and Miogeoclinal Terranes –Kolyma-Omolon, Okhotsk, Kotelnyi Island Arc Terranes and Ophiolites Plutonic Belts Paleomagnetic Review Cenozoic Tectonics Tectonic Reconstructions Outstanding Problems

3. Geological map of the Verkhoyansk-Kolyma orogenic region

4. (after Tretiakov, 2004) Middle Paleozoic grabens in the basement

5. (after Parfenov et al., 2001) Main Tectonic Units of the Verkhoyansk- Kolyma orogenic region

6. (after Parfenov et al., 2001) Schematic Cross Section

7. Structural scheme of the Verkhoyansk fold-and-thrust belt (after Prokopiev, 2001) Verkhoyansk Ridge

8. Verkhoyansk fold-and-thrust belt West Verkhoyansk sector Late Paleozoic - Early Mesozoic passive continental margin (after Parfenov, 1991)

9. Verkhoyansk fold-and-thrust belt (after Prokopiev, 2001) Olenek sector Kharaulakh segment

10. Verkhoyansk fold-and-thrust belt West Verkhoyansk sector (after Prokopiev, 1998) Kuranakh segment Orulgan segment

11. Verkhoyansk fold-and-thrust belt West Verkhoyansk sector Baraya segment (after Prokopiev, 1998) Cross-section

12. Priverkhoyansk foreland basin (after Prokopiev, 2001) Mesozoic structural stage

13. Ust’-Vilyui gas condensate field (after Gaiduk, Prokopiev, 1999) (after Safronov et al., 2001) Priverkhoyansk foreland basin Three Lower Jurassic sandstone reservoirs (180 m total) interbedded with siltstones. Gas production – 2.5 million m 3 /day Condensate fraction – 25 g/cm 3

14. Main structures of the South-Verkhoyansk sector of Verkhoyansk fold-and-thrust belt (after Prokopiev, 2001)

15. Geological cross-section across the central part of South Verkhoyansk (unpublished data) Fold and thrust (Belaya river)

16. Overlap and stitch assemblages Geochemical composition and age of granitoids Verkhoyansk fold-and-thrust belt South Verkhoyansk sector 40 Ar/ 39 Ar dating 119 to 123 Ma

17. Paleotectonic reconstructions across the South Verkhoyansk and the Okhotsk terrane (Prokopiev, Toro et al., 2003)

18. (after Parfenov et al., 2001) Kular-Nera slate belt Strike-slip deformation

19. Kinematics of deformation in the Verkhoyansk fold-and-thrust belt (after Prokopiev, 1998) 150-130 Ma130-70 Ma

20. Kolyma-Omolon Superterrane (microcontinent) Cratonal Terranes Miogeoclinal Terranes Oceanic Terranes Island Arc Terranes Accretionary Wedge Terrane

21. Structures of accretion deformations (after Oxman, 2000, 2002) Omulevka miogeoclinal terrane

22. (after Oxman, 2003, 2004) Munilkan oceanic (ophiolite) terrane P-T-t evolution ophiolites and metamorphic rocks

23. Omolon cratonal terrane Stratigraphic columns (after Tectonics, geodynamics and metallogeny..., 2001)

24. Pri-Kolyma miogeoclinal terrane (after Tectonics, geodynamics and metallogeny..., 2001) Stratigraphic columns

25. Island Arc Terranes Alazeya Khetachan Oloy

26. Oloy Is. Arc Terrane (after Tectonics, geodynamics and metallogeny..., 2001) Alazeya Is. Arc Terrane

27. (after Tectonics, geodynamics and metallogeny..., 2001) Polousnyy-Debin and Kenkel’da accretionary wedge terranes

28. (after Tectonics, geodynamics and metallogeny..., 2001) A – Pri-Kolyma, B - Beryozovka, C - Kenkel'da and Alazeya terranes

29. The Ilin’-Tas antilinorium and Zyryanka basin (after Gaiduk, Prokopiev, 1999)

30. (after Layer et al., 2001 and unpublished data) Results of 40 Ar/ 39 Ar dating of granitoids of Main and Northern batholith belts, transverse belts Oloy Oloy magmatic arc Uyandina - Yasachnaya magmatic arc

31. Paleomagnetic data (after Nokleberg et al., 1998; Tectonics, geodynamics and metallogeny..., 2001)

32. Uyandina and Irgichan pull-apart basins The northern part of the Lower Aldan basin (after Tectonics, geodynamics and metallogeny..., 2001) Cenozoic tectonics

33. Paleotectonic reconstructions (after Sengor and Natal’in, 1996)

34. Paleotectonic reconstructions (after Parfenov, 2001) L. Devonian to E. Carb. Carb. to E. Triassic L. Triassic to E. Jurassic M.-L. Jurassic E. Cretaceous Aptian to Campanian

35. Paleotectonic reconstructions (after Bondarenko, 2004)

36. Outstanding Research Questions in the Verkhoyansk fold-and-thrust belt Late Proterozoic rift of North Asia Margin. –Siberia-Laurentia Connection? Mid-Paleozoic Rift –Conjugate margins  links to outboard terranes –Verkhoyansk clastic wedge, stratigraphic links to the Arctic –Control on Mesozoic Structures Origin of the Baraya Salient Priverkhoyansk foreland subsidence

37. Outstanding Research Questions in the Verkhoyansk Mesozoic Shortening –Deep structure –Along-strike variation of structural style –Regional kinematics –Timing of deformation- thermochronology –Driving mechanisms for deformation: Collision/terrane accretion/subduction/strike-slip –Origin of magmatic rocks –Role of strike-slip deformation –Tertiary-recent tectonics

38. Outstanding Problems The available tectonic models of Northeast Asia are incomplete and contradict one another (Fujita, Newberry, 1982; Parfenov, Natal’in, 1986; Zonenshain et al., 1990; Bogdanov, Til’man, 1992; Sokolov, 1992; Parfenov, 1991, 1994, 1995, 1996; Sengor, Natal’in, 1996; Nokleberg et al., 2000; Tectonics……, 2001). Kinematics of accretion Effect of inhomogeneity of the craton boundaries Relationship between the Pz and superposed Mz tectonic events Definition of subduction and collisional structures The Growth of a Continent Goal  A Coherent Tectonic Model

39. Questions and Unsolved problems Nature and age of paleo-oceanic basins east of the Siberian continent in the Late Paleozoic-Mesozoic (Oimyakon, South Anyui) Tectonic Evolution Tectonic setting and age of Early Paleozoic arc complexes of the Alazeya upland. Nature and age of metamorphic complexes at the basement of the Omulevka and Prikolyma terranes. Problem of outlining an Early Paleozoic active continental margin along the eastern edge of the Siberian continent. Tectonic setting, age, and inner structure of ophiolites

40. Questions and Unsolved problems Where is the accretionary wedge complex between the Verkhoyansk foldbelt and Kular-Nera terrane and the Kolyma-Omolon microcontinent? North  collision with Kolyma-Omolon microcontinent South  accretion along Okhotsk margin Can we distinguish structures and magmatism due to these two synchronous processes? Accretionary Tectonics

41. Questions and Unsolved problems Evolution of Sedimentary Basins Setting and evolution of Late Pz and Mz basins surrounding the Kolyma-Omolon microcontinent (Polousnyy, In’yali-Debin synclinoria, etc.). Rift? Accretionary Prisms? Syn -collisional? Post- collisional? Determination of source areas and links. Links between basin evolution and tectonic/magmatic events Sedimentological and geochemical characterization

42. Questions and Unsolved problems Geodynamic setting of the Main and Northern Granite Belts? Volcanic Arcs and Magmatic Belts Mantle plumes and their role in Late Mesozoic geodynamic events. Paleozoic and Early Mesozoic volcanism on passive and active continental margins. In what direction did the subduction zone dip between N. Asia and Kolyma-Omolon?

43. Questions and Unsolved problems Recognition of Proterozoic and Mid-Paleozoic rift events in the Kolyma region Role Extensional Tectonics Mechanisms for large-scale extension in the Indigirka belt. Are there metamorphic core complexes in the Okhotsk, Omolon, Omulevka and Prikolyma terranes? Origin of the Indigirka lowlands?

44. Thank you!