The type-section of the Gutenstein Formation at Gutenstein revisited (Anisian, Northern Calcareous Alps, Lower Austria): Lithostratigraphy, biostratigraphy and regional overview

Abstract

Abstract New biostratigraphic data derived from the stratotype of the Gutenstein Formation at the village Gutenstein (Lower Austria) help to solve some long-standing problems about the stratigraphy of the Anisian stage within the eastern part of the Northern Calcareous Alps. At Gutenstein, the lower lithostratigraphic boundary of the Anisian Gutenstein Formation to the underlying lower Anisian Reichenhall Formation is defined, assuming a normal stratigraphic contact of the Reichenhall Formation to the underlying Werfen Formation and to the overlying Gutenstein Formation. Microfacial data confirm the sedimentary origin of the rauwackes of the Reichenhall Formation. A detailed lithostratigraphic and facies-oriented definition of the Gutenstein Formation includes prevailing thin and planar-bedded, black colored, sometimes fine-bedded limestone (rarely dolostone) and radiolarian (calcispheres) bearing, black colored mud- to wackestone, mostly containing some fine crinoid debris. Upsection, a quick change to an upper (Pelsonian) member of the Gutenstein Formation with nodular bedding planes and brachiopod-, crinoid-, conodont- and ammonite accumulations is presented. The general depositional environment of the Gutenstein Formation is interpreted as a dysoxic outer carbonate ramp deposit, with a shallowing upward trend to rather thick-bedded mid- and inner carbonate ramp settings of the Annaberg- and Steinalm formations. The approximate interval of the Anisian/Ladinian boundary within the type-section of Gutenstein is determined with help of new fossil findings such as dasycladalean green-algae. Based on distinct lithological differences on a regional scale, which occur in thick basinal stratigraphic successions within the Gutenstein Formation like at Großreifling (Styria, Bajuvaric Nappe System), at Innerfahrafeld (elevation Fuchsriegel, Lower Austria) and on mount Kasberg at Grünau (Upper Austria, Tirolic Nappe System), a subdivision of the Gutenstein Formation into a lower Gutenstein Member, and an upper Kasberg Member (= Upper Gutenstein Formation), is proposed herein. The lower member corresponds to the black, thin- and planar-bedded interval, whereas the Kasberg Member is characterized by nodular bedding planes, greater bed thicknesses and higher fossil content.