National Science Foundation Workshop
December 9-12, 2004
Stanford University, Stanford CA

Report from the Kamchatka Margin Breakout Group

Competing process of tectonic erosion and terrane accretion at the Kamchatka subduction zone

Main authors:
Paul Mann (lead)
Mark Brandon
Rick Bennett
Jeff Park
Evgeny Gordeev
Mikhail Shapiro
Mikhail Kogan
Jody Bourgeois
Vera Pononareva
Alexei Solovev
Bill Harbert

Scientific Rationale:

Kamchatka subduction zone is unique in that it shows closely spaced areas of forearc uplift and subsidence at a wavelength of ~100 km. The uplifting regions corresponds to the modern capes ( Kamchatka, Kronotsky, and Shipski) and show long-term uplift rates of up to 1 km/my. These correspond to small accreted fragment of the Kormandorsk-Aleutian arc, added over the last 20 Ma. The subsidizing areas are marked by seaward dipping unconformities of Miocene age. Subsidence rates may locally be as much as 200 m/m.y.

Nowhere in the world do we see these processes of wedge thickening and wedge thinning (probably tectonic erosion) at such a close scale. The Miocene unconformity provide a critical datum for reconstruct the evolution of the forearc in areas of both tectonic erosion and tectonic thickening.

Broader impacts

Recent studies have shown that the distribution and size of subduction zone earthquakes correlates closely with the regions of uplift and subsidence in the overriding forearc area. Our study will provide a better understanding of these processes, which can be tied in real time to the active seismicity at the Kamchatka margin.

Approaches to problem

We proposed an integrated multidisciplinary study that will combine GPS and seismology, including one or more onshore-offshore transects and MCS profiling and swath mapping in the offshore.

Relevant Background

Bazhenov, M., V. Burtman, O. Krezhovskikh, and M. Shapiro, Paleotectonic reconstruction of the Aleutian Arc-Kamchatka convergence zone, Geotectonics, 25(3), 244-256, American Geophysical Union, Washington, DC, United States, 1991, 1991.

Bazhenov, M., V. Burtman, O. Krezhovskikh, and M. Shapiro, Paleomagnetism of Paleogene rocks of the central-east Kamchatka and Komandorsky Islands: Tectonic implications, Tectonophysics, 201, 157-173, 1992.

Fedorov, P., and M. Shapiro, Neogene volcanics of the Kamchatka Isthumus and geodyamics of the Aleutian-Kamchatka junction, Geotectonics, 32(2), 122-137, 1998.

Geist, E., and D. Scholl, Large-scale deformation related to the collision of the Aleutian Arc with Kamchatka, Tectonics, 13(3), 538-560, American Geophysical Union, Washington, DC, United States, 1994.

Markov, M., V. Seliverstov, M. Khotin, and B. Dolmatov, Junction of East Kamchatka structures and the Aleutian island arc, Geotectonics, 3, 314-319, 1969.

Pechersky, D., N. Levashova, M. Shapiro, M. Bazhenov, and Z. Sharonova, Palaeomagnetism of Palaeogene volcanic series of the Kamchatsky Mys Peninsula, East Kamchatka; the motion of an active island arc, Tectonophysics, 273(3-4), 219-237, 1997.

Seliverstov, N., 1998, Structure of Kamchatkian Water Area Bottom and Geodynamic of a Junction Zone between the Kuril-Kamchatka and Aleutian Island Arcs: Moscow, Nauchnyi Mir (in Russian) (164 p., 4 plates).

Shapiro, M., Grechishkin overthrust on the shores of Kamchatka Gulf, Geotectonics, 14(3), 234-240, American Geophysical Union, Washington, DC, United States, 1980, 1980.