U.S.-Russia Joint Workshop on the Plate Tectonic Evolution of NE Russia Stanford University Dec. 9-12, 2004 Sponsored by the U.S. National Science Foundation (Tectonics and International Divisions) with travel support for Russian scientists shared by Placer Dome, Shell International, Anadarko(?), Encana, Exxon, Pacific Rim Geology Consultants for Fall 2004 AGU Special Session in honor of Leonid Parfenov San Francisco, CA, Dec. 16th

Organizers and Conveners U.S.A.: Elizabeth Miller, Jeremy Hourigan, David Stone, Jaime Toro, Kaz Fujita, Paul Layer Russia: Slava Akinin, Boris Natalin, Andrei Prokopiev, Sergei Sokolov, Alexander Khanchuk, Pavel Minyuik

Workshop Mandates: · Share knowledge about a part of the earth whose geologic evolution is still poorly known · Explore mutual scientific goals and set research priorities · Energize a series of plans for attaining these goals NE Russia U.S.

Russia and N.America share: ·A linked geologic and plate tectonic history whose details are critical for understanding our natural resources. ·Pacific plate margin · active subduction ·earthquake and volcanic hazzards · ore deposits, hydrocarbons · Arctic margin ·vast poorly known continental shelves ·hydrocarbon potential (Nokleberg et al. 1998)

Overview Presentations: What do we know? What are the major unsolved tectonic questions? 1.The Arctic Margin: Elizabeth Miller and Boris Natal’in 2. Verkhoyansk-Kolyma Orogenic Belt: Andrei Prokopiev Jaime Toro 3.Pacific Margin: Jeremy Hourigan, Alexander Khanchuk, Sergey Sokolov 4.Magmatic Belts of NE Russia: Slava Akinin and Paul Layer 5. Plate Boundaries, Seismicity and Geophysics: Kaz Fujita, Mikhail Kogan and Vadim Levin

Overview Presentations: What do we know and what are the major unsolved questions about the geology and tectonics of North East Russia and adjacent North America? The Arctic Margin of NE Russia: Outstanding Questions and Problems from the Arctic Ocean Perspective Elizabeth Miller Stanford University, Stanford CA

Their report: Conveners *Bernard Coakley, Geophysical Institute - UAF *Steve Forman, University of Illinois - Chicago *Rick Murray, Boston University *John Tarduno, University of Rochester This meeting follows: A NSF Workshop on the Amerasian Basin and its Margins June 8th and 9th 2004, Washington, DC We were there: Kaz Fujita, Paul Layer, Elizabeth Miller, Jaime Toro, Andrei Zayonchek,

Workshop on the Amerasian Basin and its Margins Our incomplete knowledge of the history of the Amerasian Basin and the Arctic has been inferred from the limited stratigraphic record exposed on the Canadian and American continental margins. During the last few years an outpouring of data collected in the Arctic Ocean basin from satellites, airplanes and submarines has been made available and compiled into revised and much-improved maps and grids of bathymetry, gravity anomalies and magnetic anomalies. Terrestrial studies on the adjacent margins in Eurasia and North American have yielded new geologic insights. With these new data, it is now possible to formulate testable hypotheses about the tectonic, magmatic and paleoclimate history of the Amerasian Basin. Further progress will require international, coordinated field programs (e.g., IPY), including scientific drilling (e.g., IODP). Their report:

Workshop on the Amerasian Basin and its Margins Knowledge of the Arctic Basins is based on the limited record on the continental margins. Outpouring of new data from satellites, airplanes, and submarines  Better bathymetry, gravity, and magnetic maps. Terrestrial studies  new geologic insights. New data  tectonic, magmatic, and paleoclimate history of the Amerasian Basin? Further progress will require international, coordinated field programs (e.g., IPY), including scientific drilling (e.g., IODP). Their report:

IBCAO (2000) Main bathymetric features of the Arctic Ocean

IBCAO (2000) EURASIAN BASIN AMERASIAN BASIN Eurasian Basin: Continuation of mid-Atlantic spreading center (<55 Ma ) Amerasian Basin: A more complex and debated origin (~ Ma)

IBCAO (2000) EURASIAN BASIN AMERASIAN BASIN Lomonosov Ridge Alpha-Mendeleev Ridge Gakkel Ridge Makarov Basin Interpretation of how the Amerasian Basin formed affects interpretations of Lomonosov, Alpha Ridges, Makarov Basin and Chukchi Platform Chukchi Platform

IBCAO (2000) Limited seismic data from the Amerasian Basin Only ONE drillhole Alaskan and Canadian margins are well- characterized (seismic and drilling) compared to the East Siberian Shelf about which nearly nothing is known. U.S.G.S. TACT Project NSF CD Bering- Chukchi Project ICEX Hole

Geology: Persits and Ulmishek, (2003), USGS Aeromagnetic Data: Glebovsky et al. (2000), Naval Research Lab

Reconstruction of the Arctic at 140 Ma (Lawver et al.2002)

Reconstruction of the Arctic at 120 Ma (Lawver et al. 2002) Implications: Lomonosov Ridge (LR) is a transform fault, Chukotka came from Canada, S.Anuyi was a large ocean, Alpha Ridge, a younger Cretaceous hot spot track.

Other models proposed for the formation of the Amerasian Basin -none except the rotation model are viable for Alaska given the geologic and magnetic anomaly constraints Rifting models for Amerasian Basin summarized by Lawver and Scotese (1990) with specific predictions for rift versus transform origin of margins and the geologic matches of margins. Base map IBCAO (2000) Amerasian Basin Eurasian Basin Alaska Russia Canada Lomonosov Ridge

Old aeromagnetic data and its interpretations suggested Makarov Basin spreading from 80 Ma to 60 Ma. ( Taylor et al., 1981; Vogt et al., 1982) Seismic velocities suggest continental or thinned continental crust (recent refs.) Normal fault origin of the Lomonosov Ridge (Sweeney et al., 1982)

The answers to these questions lie in the geology of Arctic Russia: ·Is Chukotka’s stratigraphy like Canada or like somewhere else? ·Is the South Anyui Zone the remnant of an extensive ocean basin? When did it close ? Does the time of deformation fit the model? ·What is NE Arctic Russia’s magmatic history? Is there evidence for a Cretaceous hot spot track?

Russia Alaska Canada Eocene (55 Ma) opening of Eurasian Basin by Gakkel Ridge spreading Outstanding problems also exist with the younger geology of NE Russia ?

Main Question: What exactly happens to this oceanic rift in continental crust? 500 km of new ocean crust… Where and how is this extension accommodated through geologic time?

Federal Institute for Geosciences and Natural Resources (BGR) Hannover Sevmorneftegeofizica (SMNG), Murmansk ( Rifting in the Laptev Sea: continuation of Gakkel Ridge into Continental Crust

Federal Institute for Geosciences and Natural Resources (BGR) Hannover Sevmorneftegeofizica (SMNG), Murmansk ( Seismically mapped normal faults don’t account for all the extension

Take-home comments from the Amerasian Basin NSF workshop: What can we do on land? 1.Compile/study location, extent of Paleozoic and older deformational belts in the circum-Arctic region to establish tie points across the basin to determine the origin of Amerasian Basin. 2.How does continental magmatic history of NE Russia relate geographically to Alpha-Mendeleev Ridge? Can these rocks, their age and geochemistry help constrain its origin? 3. Study sedimentary successions that closely pre- and post-date inferred age of Amerasian Basin opening. Distribution, ages, provenance-do these reflect changing paleogeographies? How? 4. Neotectonics, earthquakes, plate boundaries and global tectonics: How is North Atlantic spreading transferred through Russia? What are plate motion linkages between Atlantic spreading and Pacific subduction?