Field Trip F2: Sediments of the Ries Crater Lake (Miocene, Southern Germany)

The Nördlinger Ries is a circular, flat depression of 22-24 km diameter separating the Jurassic limestone plateaus of the Franconian and Swabian Alb in Southwest-Germany. Its centre is located 110 km NW of Munich, 70 km SSW of Nuremberg and 110 km E of Stuttgart. The Ries basin was formed approximately 15 Million years ago (Gentner & Wagner, 1969; Staudacher et al., 1982) by an impact of a stony meteorite less than 1 km in size (Shoemaker & Chao, 1961; Stöffler, 1977). The Ries crater represents one of the best preserved and best investigated impact structures on Earth (Bayerisches Geologisches Landesamt 1969, 1974, 1977; Hüttner & Schmidt-Kaler 1999; Stöffler & Ostertag 1983). It gained wide public attention (e.g., Metz 1974, Steinert 1974, Lemcke 1981, Kavasch 1985, Pösges & Schieber 1994; Schieber 2004) and served as training site for Apollo 17 astronauts in August 1970 (e.g., Margolin 2000). However, apart from its impact nature, the Ries basin offers a great opportunity to study fossil lacustrine microbialites. Such lacustrine deposits within impact structures are of increasing interest for understanding the origin and evolution of early life on Earth, and possibly other planets (Cockell & Lee 2002, Osinski et al. 2005, Cabrol et al. 2001). Therefore, the focus on this field trip is on microbial and algal build-ups, their facies context, and the discussion of microbial effects and lake water chemistry.excursionguid