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Central ring structure identified in one of the world's best-preserved impact craters

¹ Alfred Wegener Institute for Polar and Marine Research, Columbusstraße, 27568 Bremerhaven, Germany
² Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, 14473 Potsdam, Germany

Seismic refraction and reflection data were acquired in 2000 and 2003 to study the morphology and sedimentary fill of the remote El'gygytgyn crater (Chukotka, northeastern Siberia; diameter 18 km). These data allow a first insight into the deeper structure of this unique impact crater. Wide-angle data from sonobuoys reveal a five-layer model: a water layer, two lacustrine sedimentary units that fill a bowl-shaped apparent crater morphology consisting of an upper layer of fallback breccia with P-wave velocities of 3000 m/s, and a lower layer of brecciated bedrock (velocities >3600 m/s). The lowermost layer shows a distinct anticline structure that, by analogy with other terrestrial and lunar craters of similar size, can be interpreted as a central ring structure. The El'gygytgyn crater exhibits a well-expressed morphology that is typical of craters formed in crystalline target rocks.

Key Words: impact crater • El'gygytgyn • lakes • seismic refraction • seismic reflection