Gosau Group

Gosau Group
Stratigraphic range: Late Cretaceous-Eocene
~
Rocks of the Gosau Group exposed in the Imster Muttekopf
Typestratigraphic group
Sub-units
  • Eastern realm:
    Upper Gosau Subgroup - Piesting & Zweiersdorf Formations
    Lower Gosau Subgroup - Kreuzgraben, Maiersdorf & Grünbach Formations
  • Western realm:
    Upper Gosau Subgroup - Ressen, Nierental & Zwieselalm Formations
    Lower Gosau Subgroup - Kreuzgraben, Schönleiten, Streiteck, Noth, Grabenbach, Hochmoos & Bibereck Formations
OverliesUnconformity with folded and faulted Permian to Lower Cretaceous rocks
Thickness2,200–2,600 m (7,200–8,500 ft)
Location
Coordinates47°36′N 13°30′E / 47.6°N 13.5°E / 47.6; 13.5
Approximate paleocoordinates32°06′N 15°36′E / 32.1°N 15.6°E / 32.1; 15.6
RegionCentral Europe
CountryAustria
Germany
Slovakia
ExtentGosau Basin, Limestone Alps
Gosau Group is located in Austria
Gosau Group
Gosau Group
Gosau Group
Gosau Group
Gosau Group
Gosau Group
Gosau Group
Gosau Group
Gosau Group (Austria)

The Gosau Group (German: Gosau-Gruppe) is a geological stratigraphic group in Austria, Germany and western Slovakia and Romania whose strata date back to the Late Cretaceous to Eocene.[1][2] It is exposed in numerous sporadic isolated basins within the Northern Calcareous Alps. It is divided into two subgroups, the Lower Gosau Subgroup which dates from the Turonian to Campanian, approximately 90 to 75 Ma and the Upper Gosau Subgroup which dates to the Santonian to Eocene, about 83.5 to 50 Ma.

The formations within each subunit vary significantly between basins. The thickness of the unit varies in but in the Gosau Basin it is over 2,300m thick.[3](p21) The sequence is largely marine, but the Grünbach Formation represents a terrestrial deposit and to the south-west of Vienna coal deposits in the Gosau have been worked.[3](p21) Many of the units of the group are fossiliferous, typically providing marine fossils such as ammonites, though terrestrial remains including those of dinosaurs are known from the Grünbach Formation and Schönleiten Formation.

Stratigraphic contacts between the Gosau beds and any earlier units are generally unconformable and the isolated pockets in which they occur are often fault bounded.[3](p21) Because the Gosau Group is a lithostratigraphic unit the time of deposition (in Ma before present) may be somewhat variable from place to place but they can be dated by their fossil content and the younger Gosau beds can also be distinguished from those which are older than lower Campanian by the assemblage of 'heavy minerals' they contain.[4]

Tectonic relevance

Upper Cretaceous sediments, particularly the Gosau beds, have been of importance in interpreting the tectonic history of the Northern Calcareous Alps.[3](p19 & 21)

Gosau beds rest unconformably on thrust contacts between sheets in the Northern Calcareous Alps. The unconformable relationship indicates that the early stages of thrusting ('pre-Gosau') had commenced before the Gosau units were deposited in the upper Cretaceous. During later 'post-Gosau' movements the Gosau beds were severely faulted. Those later events involved flexure folding and the northward movement of the Northern Calcareous Alps resulting in it overlying areas of the molasse deposits of Miocene age.[5]

Fossil content

Among others, the following fossils have been described from the Gosau Group:[6][7]

reptiles
Genus Species Presence Notes Images
Struthiosaurus S. austriacus Niederösterreich, Austria [8]
Mochlodon M. suessi A rhabdodontid iguanodont[8]
Rhadinosaurus R. alcinus Possible indeterminate ankylosaur remains[8]
"Crataeomus" C. lepidophorus Later found to be synonymous with Struthiosaurus austriacus[8]
C. pawlowitschii Later found to be synonymous with Struthiosaurus austriacus in partim[8]
"Danubiosaurus" D. anceps Later found to be indeterminate ankylosaurian and Struthiosaurus austriacus remains in partim[8]
"Indeterminate fragments"[9]
"Hoplosaurus" H. ischyrus Later found to be synonymous with Struthiosaurus austriacus[8]
"Leipsanosaurus" L. noricus Later found to be synonymous with Struthiosaurus austriacus[8]
"Pleuropeltus" P. suessi Later found to be synonymous with Struthiosaurus austriacus in partim[8]
"Megalosaurus" M. pannoniensis Later found to be indeterminate theropod remains[8]
Ornithocheiridae indet. [10][11]
Mollusca
Genus Species Presence Notes Images
"Trochactaeon" T. conicus' Nördliche Kalkalpen, Niederösterreich, Austria Very common fossil, rock forming
Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

See also

References

  1. ^ Höfling, 1985
  2. ^ McCann, 2008
  3. ^ a b c d Oxburgh, E.R. (1968). The Geology of the Eastern Alps. The Geologists Association. ISBN 978-0-913312-33-9. Retrieved 22 July 2025.
  4. ^ Stattegger, Karl (1987). "Heavy minerals and provenance of sands; modeling of lithological end members from river sands of northern Austria and from sandstones of the Austroalpine Gosau Formation (Late Cretaceous)". Journal of Sedimentary Research. 57 (2): 301–310. doi:10.1306/212F8B0C-2B24-11D7-8648000102C1865D. Retrieved 7 August 2025.
  5. ^ Linzer, Hans-Gert; Ratschbacher, Lothar; Frisch, Wolfgang (1995). "Transpressional collision structures in the upper crust: the fold-thrust belt of the Northern Calcareous Alps". Tectonophysics. 242 (1–2): 41–61. Bibcode:1995Tectp.242...41L. doi:10.1016/0040-1951(94)00152-Y. Retrieved 5 August 2025.
  6. ^ Gosau Group at Fossilworks.org
  7. ^ Lower Gosau Group at Fossilworks.org
  8. ^ a b c d e f g h i j Weishampel, 2004, pp. 588-593
  9. ^ "Table 17.1," in Weishampel et al., 2004, p.367
  10. ^ Zitteliana
  11. ^ Agnolin & Varricchio, 2012

Bibliography

Further reading

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