Gosau Group

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.

Gosau Group
Stratigraphic range: Late Cretaceous-Eocene ~90–50 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Rocks of the Gosau Group exposed in the Imster Muttekopf
Type	stratigraphic 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
Overlies	Unconformity with folded and faulted Permian to Lower Cretaceous rocks
Thickness	2,200–2,600 m (7,200–8,500 ft)
Location
Coordinates	47.6°N 13.5°E / 47.6; 13.5
Approximate paleocoordinates	32.1°N 15.6°E / 32.1; 15.6
Region	Central Europe
Country	Austria Germany Slovakia
Extent	Gosau Basin, Limestone Alps
Gosau Group (Austria)

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

• List of dinosaur-bearing rock formations