Numerical modeling of tektite origin in oblique impacts: Implication to Ries-Moldavites strewn field


Authors: Artemieva N, Pierazzo E, Stöffler D

Published in: Bulletin of Geosciences, volume 77, issue 4; pages: 303 - 311; Received 1 July 2002; Accepted in revised form 21 September 2002;

Keywords: impact crater, tektite, moldavite, melt, numerical modeling, Ries-Moldavite strewn field, Germany, Czech Republic,

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On the basis of detailed geological, petrographic, geochemical, and geographical information we have performed a numerical modeling study of three related and coeval impact features: The Steinheim crater (apparent diameter Da = 3.8 km), the Ries crater (Da = 24 km) in Southern Germany, and the moldavite (tektite) strewn field in Bohemia and Moravia (Czech Republic), Lusatia (East Germany), and Lower Austria. The moldavite strewn field extends from about 200 km to 450 km away from the centre of the Ries to the ENE forming a fan with an angle of about 57°. According to this modeling work, an oblique impact of a binary asteroid from a WSW direction appears to be a reasonable working hypothesis to explain the setting of the craters and the formation and distribution of the moldavites. We carried out a series of 3D hydrocode simulations of a Ries-type impact. The results confirm previous results indicating 30° from the horizon as the most probable angle for near surface melting, and, consequently for the formation of tektites. Finally, the simulation of the motion of impact-produced tektite particles through the atmosphere produces a narrow-angle, downrange, distant distribution of the moldavite tektites in a fan-like field with an angle of about 75°. Although the calculated distribution still deviates to some degree from the known distribution of the moldavites, our results represent an important step toward a better understanding of the origin and distribution of the high-velocity surface melt (tektites) and the low-velocity, deep-seated melt (coherent clast-laden melt) resulting from an oblique impact on a stratified target.