Cretaceous biostratigraphy and lithostratigraphy of the Glinzendorf Syncline based on well Ganserndorf UeT3 (Vienna Basin, Austria)

The 2200 m thick Cretaceous units of well Ganserndorf UeT3 have been biostratigraphically analyzed based on cuttings from 3210 m to 5140 m. The deposits from the Tirolic Glinzendorf Syncline (a part of the buried Northern Calcareous Alps) can be largely correlated with the Lower Gosau Subgroup of the Grunbach Syncline. An exception is the basal unit, which has no equivalent in the Grunbach Syncline. This lower unit is subdivided into a non-marine lower and a largely marine upper part. No age constraints are available for the lower part, whereas the upper part has a possible age range from middle Turonian to Coniacian. For this unit, which is documented for the first time from the Glinzendorf Syncline, we propose Glinzendorf Formation as new lithostratigraphic term. The Glinzendorf Fm. is overlain by the Grunbach Fm., which is intercalated by a thick unit of conglomerates. These are interpreted as equivalents of the Dreistetten Conglomerate Mb. The calcareous nannofossils of these units suggest a latest Santonian to early Campanian age. Non-marine conditions prevailed during deposition of the Grunbach Fm., but marine incursions are indicated for parts of the Dreistetten Conglomerate Mb. The top of the Grunbach Fm. is formed by an about 50-m-thick unit of coal, rich in Characeae oogonia, which, together with the Dreistetten conglomerates serve as marker layer for correlation with the outcrops in the Grunbach Syncline. The Grunbach Fm. is overlain by marls and silty shales of the Piesting Fm. for which a late Campanian and Maastrichtian age is documented. Marine conditions predominated during this interval. The topmost unit in well Ganserndorf UeT3 is overthrusted on the Maastrichtian Piesting Fm. and represents Campanian sandstones and conglomerates of the Grunbach Fm. This Ganserndorf Thrust is detected and biostratigraphically constrained for the first time.