New evidence for the impact origin of the Ries Basin, Bavaria, Germany

Abstract

The Ries basin is a shallow, nearly circular depression about 17 miles in diameter that lies between the Swabian and Franconian plateaus of southern Germany. Great masses of breccia and a system of thrust sheets associated with the Ries have been studied by German geologists for about a century. E. Werner and Otto Stutzer suggested that the Ries was an impact crater, but the consensus of the principal investigators has been that it was formed by some sort of volcanic explosion. The only direct evidence of magmatic activity at the Ries is the presence of glass in scattered patches of a breccia called suevite. Some of the glass has long been recognized as sintered fragments of old crystalline rocks. We have found that glasses of various composition coexist in single specimens of suevite. In addition, coesite, a high‐pressure polymorph of SiO2, and lechatelierite, SiO2 glass, occur in the sintered rocks in the suevite. The presence of the same phases in sintered rock fragments at Meteor Crater, Arizona, and the coexistence of glasses of different composition suggest that the glassy components of suevite are of impact rather than volcanic origin.

Shock waves—Phenomenology, experimental, and numerical simulation

“…The durations of pressure pulses have probably been too short. Coesite was found in suevite of the Ries crater embedded in diaplectic quartz glass (Stˆffler 1971b;Shoemaker and Chao 1961). Shock melting of orthoclase, oligoclase, and labradorite was produced in shock-recovery experiments at pressures between 47.5-57.5 GPa, when the post-shock temperature was high enough (Stˆffler and Hornemann 1972).…”

“…In Germany, the Nˆrdlinger Ries and the Steinheimer Becken are two well-known large craters with diameters of 24 and 3.8 km, respectively. The shock metamorphism of the rocks in these craters has been investigated extensively (e.g., Shoemaker and Chao 1961;Stˆffler 1971Stˆffler , 1972Stˆffler , 1974Stˆffler and Langenhorst 1994). Zones with characteristic shock effects in the minerals could be established that indicate distinct levels of shock wave energy.…”

Estimating shock pressures based on high-pressure minerals in shock-induced melt veins of L chondrites

“…Early studies of shock metamorphism concentrated on terrestrial samples that contained high-pressure silicates such as coesite and stishovite (Chao et al 1960;Chao et al 1962;Chao 1967;Shoemaker and Chao 1961). Shock deformation features in meteorites were studied intensively by optical microscopy and X-ray diffraction in the late 1960s (Milton and De Carli 1963;Fredriksson et al 1963;Van Schmus and Wood 1967;Heymann 1967;Carter et al 1968;Van Schmus and Ribbe 1968;Taylor and Heymann 1969;Stöffler 1972Stöffler , 1974.…”

Geobiology of Stromatolites

“…The outcrop exposes the contact between the "Bunte Breccie", an ejecta deposit largely composed of clasts and blocks of the Triassic-Jurassic sedimentary sequence of this area, and the suevite, an impact-melt-bearing breccia with microscopic inclusions of the high-pressure minerals phases stishovit, coesit, diamond, and silicon carbide (Shoemaker & Chao 1961, Chao & Littler 1963, Hüttner 1969, Hough et al 1995. Most noticable are cm to dm-sized black vesicular glass bombs, besides of highly-shocked crystalline rock fragments.…”