Tectonic Overview of the Verkhoyansk-Kolyma Orogenic Region

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

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

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

6. SchematicCross Section (after Parfenov et al., 2001)

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

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 Olenek sector Kharaulakh segment (after Prokopiev, 2001)

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

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

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

13. Priverkhoyansk foreland basin Ust’-Vilyui gas condensate field • Three Lower Jurassic sandstone reservoirs (180 m total) interbedded with siltstones. • Gas production – 2.5 million m3/day • Condensate fraction – 25 g/cm3 (after Safronov et al., 2001) (after Gaiduk, Prokopiev, 1999)

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 Geological cross-section across the central part of South Verkhoyansk (unpublished data) Fold and thrust (Belaya river)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. Verkhoyansk fold-and-thrust belt South Verkhoyansk sector Geochemical composition and age of granitoids Overlap and stitch assemblages 40Ar/39Ar dating 119 to 123 Ma

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

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

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

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

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

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

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

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

25. Island Arc Terranes • Alazeya • Khetachan • Oloy

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

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

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

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

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

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

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

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

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

35. Paleotectonic reconstructions (after Bondarenko, 2004)

36. Outstanding Research Questionsin 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 Questionsin 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 Growth of a Continent • 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 Goal  A Coherent Tectonic Model

39. Questions and Unsolved problems Tectonic Evolution • Problem of outlining an Early Paleozoic active continental margin along the eastern edge of the Siberian continent. • Nature and age of paleo-oceanic basins east of the Siberian continent in the Late Paleozoic-Mesozoic (Oimyakon, South Anyui) • Tectonic setting, age, and inner structure of ophiolites • 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.

40. Questions and Unsolved problems Accretionary Tectonics • 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?

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? Sedimentological and geochemical characterization Links between basin evolution and tectonic/magmatic events Determination of source areas and links.

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

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

44. Thank you!