Tristel Formation

The Tristel Formation is a stratigraphic formation of the northern-central Alps, deposited between the late Barremian and the early Aptian of the Early Cretaceous. It consists of thickly banked limestones, marls and shales.[1] It is the lowest formation of the Bündnerschiefer and belongs to the Rhenodanubic Group.[2]

Tristel Formation Stratigraphic range: Late Barremian-Early Aptian ~127–123 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Tristel Formation near its type locality, looking at Naafkopf from the southwest
Type	Geological formation
Unit of	Rhenodanubic Group, Bündnerschiefer
Thickness	150–250 m (490–820 ft)[1]
Lithology
Primary	Limestone, marl
Other	Shale
Location
Coordinates	47.060767°N 9.607067°E / 47.060767; 9.607067
Region	Allgäu, Oberbayern, Tirol, Vorarlberg
Country	Austria  Germany  Liechtenstein   Switzerland
Type section
Named for	Tristel, a mountain next to the Naafkopf
Named by	Schwizer
Year defined	1984

Outcrops can be found in the Engadin window, the Tauern window, the Rechnitz window, and many localities of the Penninic realm of the eastern and western Alps.[3]

The type locality is the area around the Naafkopf (47.060767°N 9.607067°E / 47.060767; 9.607067) in the border region of Austria, Liechtenstein and Switzerland.[1]

The Tristel Formation can be correlated with the Klus Formation in Graubünden and the Couches de l’Aroley Formation in Savoie (France) and Valais (Switzerland).[4][5]