Facies (2009) 55:63–87 DOI 10.1007/s10347-008-0155-3 123 ORIGINAL ARTICLE Spatial and temporal development of siliceous basin and shallow-water carbonate sedimentation in Oxfordian Northern Calcareous Alps Matthias Auer · Hans-Jürgen Gawlick · Hisashi Suzuki · Felix Schlagintweit Received: 6 November 2007 / Accepted: 23 June 2008 / Published online: 12 August 2008  Springer-Verlag 2008 Abstract The Late Jurassic succession of Mount Retten- stein (central Northern Calcareous Alps, Austria) is unique in comparison to all other sections known in the Northern Calcareous Alps because it provides the oldest coexistence of radiolarite basin sedimentation with contemporaneous shallow-water carbonate intercalations. An up to 3.5-m- thick debris Xow made up of shallow-water carbonate detri- tus with a radiolaritic matrix is overlain by thin (calcareous) radiolarite, followed by several hundreds of meters of shal- low-water carbonates of the Plassen Formation. Benthic foraminifers (Labyrinthia mirabilis Weynschenk and Alve- osepta aV. jaccardi) and the radiolarian associations indi- cate a depositional age of both the debris Xow and the basal Plassen Formation around the boundary of Middle/Late Oxfordian resp. in the Late Oxfordian. This is as yet the Wrst unambiguous evidence of Oxfordian shallow-water sedimentation in the Northern Calcareous Alps. This early neritic stage with the settlement of ooid bars and coral- stromatoporoid-reefs, evidenced by the debris Xow resedi- ments in siliceous basin sedimentation, is followed by the deWnite, rapid progradation of the actual Late Oxfordian/ Kimmeridgian–Berriasian Plassen Carbonate Platform with its steep slope conWguration. Assumably, this evolution was steered by a mixture of both global environmental and regional tectonic constraints. Keywords Eastern Alps · Oxfordian · Plassen Carbonate Platform · Debris Xow · Biostratigraphy · Radiolarians · Foraminifera · Tethys Introduction Knowledge about the Late Middle to Late Jurassic radiola- rites of the western Neotethys and Penninic-Piedmont realms has largely increased since the 1980s. The advance- ment of radiolarian biostratigraphy originally implemented by P. O. Baumgartner and his InterRad Jurassic-Cretaceous working group (Baumgartner 1984; Baumgartner et al. 1995a: Unitary Association Zonation for radiolarians of the Tethyan realm) improved the understanding of these regionally distributed siliceous deep-water series lacking of any index macrofossils. Together with breccia analysis, the application of radiolarian biostratigraphy had also a great impact on the understanding of the tectono-stratigraphic evolution of the Northern Calcareous Alps as it enabled to prove the heterochroneity of diVerent partial basins (e.g., Gawlick et al. 1999a, 2007a; Gawlick and Suzuki 1999; Missoni et al. 2001; Missoni 2003; Gawlick and Frisch 2003; Suzuki and Gawlick 2003a, b; Auer et al. 2006a for comparison: Diersche 1980). Nevertheless, despite the large progress the resolution of radiolarian biostratigraphy is still far from satisfactory particularly for the Oxfordian to Early Kimmeridgian period and thus for the time, when the siliceous basin sedimentation of the Northern Calcareous Alps was gradually replaced by hemipelagic and/or shal- low-water carbonate sedimentation. M. Auer · H.-J. Gawlick (&) · H. Suzuki · F. Schlagintweit Department of Applied Geosciences and Geophysics: Chair of Prospection and Applied Sedimentology, University of Leoben, Peter-Tunner-Str. 5, 8700 Leoben, Austria e-mail: hans-juergen.gawlick@mu-leoben.at M. Auer e-mail: das_auerli@web.de H. Suzuki e-mail: hsuzuki@res.otani.ac.jp F. Schlagintweit e-mail: ef.schlagintweit@t-online.de