Transcript ~7.7MB - Stanford University

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
After the field 1999
Leonid and Irina’s dasha party
WELCOME TO CALIFORNIA!
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.
NE Russia and N.A. share:
·A linked geologic and
plate tectonic history whose
details are critical for
understanding evolution of
our continents and the setting
for our natural resources.
(base map from Nokleberg et al. 1998)
·Pacific plate margin
· active subduction
· ore deposits, hydrocarbons
·earthquake and volcanic
hazards
· Arctic margin
·vast poorly known
continental shelves
·hydrocarbon potential
Overview Presentations: Dec. 9, 2004
What do we know?
What are the major unsolved tectonic questions?
The plate tectonic framework of
NE Russia: Pacific and Arctic
Perspectives
1. The Pacific View: Warren Nokleberg (U.S. Geological Survey)
2. The Arctic View: Larry Lawver (University of Texas, Austin)
Overview Presentations: Dec. 10, 2004
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:
The Arctic Margin of NE Russia:
Outstanding Questions from
the Arctic Ocean Perspective
Elizabeth Miller and Jaime Toro
Stanford University, Stanford CA
West Virginia University, Morgantown WV
This meeting follows:
NSF Workshop on the Amerasian Basin and its Margins
held June 8th and 9th 2004, Washington, DC
Conveners
*
Bernard Coakley, Geophysical Institute - UAF
*
Steve Forman, University of Illinois - Chicago
*
Rick Murray, Boston University
*
John Tarduno, University of Rochester
We were there: Kaz Fujita, Paul Layer, Elizabeth Miller, Jaime Toro,
Andrei Zayonchek,
Their report: http://www.geo-prose.com/amerasian/
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  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: http://www.geo-prose.com/amerasian/
Main
bathymetric
features of
the Arctic
Ocean
IBCAO (2000)
Eurasian Basin:
Continuation of
mid-Atlantic
spreading center
(<55Ma)
Amerasian Basin:
A more complex
and debated origin
(~ 135-120 Ma)
EURASIAN
BASIN
IODP-ACEX
AMERASIAN
BASIN
IBCAO (2000)
http://www.rcom-bremen.de/English/IODP.html
Where to read about the new results
Our knowledge before
now
56 Ma
shallow marine
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
unconformity
Late Cretaceous
(80 Ma) marine
www.ecord.org/about/j/533AGUposter.pdf
Jackson (2000)www.cseg.ca/conferences/2000/2000abstracts/316.PDF
Canada
Russia
?
Eocene (55 Ma)
opening of Eurasian Basin
by Gakkel Ridge spreading
How does this rift end and/or
propagate into continental crust?
500 km of new ocean crust… Where
and how is this extension accommodated
through geologic time?
Laptev Sea
Rifting in the Laptev Sea: continuation of Gakkel Ridge into Continental Crust
Federal Institute for Geosciences and Natural Resources (BGR) Hannover
Sevmorneftegeofizica (SMNG), Murmansk (http://www.bgr.de/)
Seismically mapped normal faults don’t account for all the extension
Federal Institute for Geosciences and Natural Resources (BGR) Hannover
Sevmorneftegeofizica (SMNG), Murmansk (http://www.bgr.de/)
Mackey et al.
(unpublished
Draft, 2004)
Alpha-Mendeleev
Ridge
EURASIAN
BASIN
Interpretation of
how the Amerasian Gakkel
Basin formed
Ridge
affects
interpretations of
Lomonosov
Lomonosov, Alpha
Ridge
Ridges, Makarov
Basin and Chukchi
Cap
Makarov Basin
AMERASIAN
BASIN
Chukchi
Cap
IBCAO (2000)
·Alaskan and Canadian
margins are wellcharacterized (seismic
and drilling) compared
to the East Siberian
Shelf about which
nearly nothing is
known.
·Limited seismic,
dredge, shallow core
data from the Canada
Basin (Grantz et al.,’90,’98)
IBCAO (200
ACEX
Hole
Canada
Basin
·Crustal Transects
·Alpha-Mendeleev
Ridge and Makarov
Basin are controversial
·New IODP-ICEX hole
East Siberian
Shelf
NSF CD BeringChukchiProject
U.S.G.S.
TACT
Project
Amerasian
Basin
Lomonosov
Ridge
Canada
Eurasian
Basin
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)
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.
Aeromagnetic Data:
Glebovsky et al. (2000),
Naval Research Lab
Geology: Persits and
Ulmishek, (2003), USGS
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.
Normal fault origin of
Lomonosov-Makarov
(Sweeney et al., 1982)
The answers to the origin of Canada Basin lie in 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?
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. Study sedimentary successions that closely pre- and post-date inferred
age of Amerasian Basin opening. Distribution, ages, provenance-do
these reflect changing paleogeographies? How?
3. 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?
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