Chemical composition of Ries glass bombs

Thirty-two chemical analyses of glass bombs, taken from various suevitelocalities within and outside the Ries crater, Germany are presented. Two main glass types, (I: non recrystallized, III: highly recrystallized), and one intermediate (II: slightly recrystallized) can be distinguished. All glass bombs originate from the same melt. The textural differences between the types I, II and III are due to locally different cooling rates of the suevite. The melt was formed in the impact crater by shock melting of a limited mass of magmatic or metamorphic rocks of uniform granitic composition. Minor chemical differences between the glasses are mainly caused by later oxidation and leaching processes which were controlled by the degree of recrystallization. Some textural features are discussed by which products of incomplete shock melting (like the Ries glasses) can be distinguished from rocks formed by differential anatexis or magmatic dissolution.