Hallstatt Lime
The Hallstatt Limestone is a lithostratigraphic unit of the Middle and Upper Triassic in the Northern Limestone Alps . The Hallstatt limestones have become famous for their wealth of fossils . The term Hallstätter Kalke was coined in 1853 by the geologist Franz von Hauer .
Definition and distribution area
The Hallstatt limestone is a development of the Hallstatt Facies Zone in the Northern Limestone Alps, unlike the shallow water formations above it, such as the Dachstein limestone , the Hallstatt limestone originated in basins and associated threshold areas at a depth of around 50 to 200 meters. The Hallstatt Facieszone extends from Lofer in the west over Hallein , the Lammertal , Salzkammergut , the foreland of the Hochschwab , the Mürz Valley Alps and the Hohe Wand to Hernstein. A characteristic of this zone is a thin development of Triassic rocks compared to neighboring zones of the Northern Limestone Alps.
Since the Hallstatt limestone occurs in different zones, some of which are spatially separated from each other, their age as well as their relation to the surrounding units is not uniform. In many areas the Hallstatt limestones do not reach the entire temporal range from the middle anisium to the upper norium . In the stratigraphic table of Austria , a salt mountain facies in the central part of the Northern Limestone Alps is distinguished from a Mürz valley facies further east. In the area of the salt mountain facies, the Hallstatt limestone is underlain by the Steinalm formation and overlaid by the Zlambach layers . It is laterally interlocked with Wetterstein limestone , Reifling formation , Reingrabener slate , purple to green slab limestone and Pötschenkalk . In the area of the Mürz Valley facies there is sometimes a layer gap in the carnium, sometimes Lechkogel layers and Waxeneck limestone or Waxeneck dolomite take place here.
description
The Hallstatt limestones are red, gray, white and various shades of micritic limestone with predominantly pelagic fauna and low clay content. In addition to the well-known ammonite fauna , fossils include bivalves - protoconche in abundance . In the Hallstatt Limestone, fossils occur mainly in stratified deposits and in synsedimentary crevices.
The normal layer sequence of the Hallstatt Limestone according to the geologist Alexander Tollmann in his monograph on the Northern Limestone Alps:
- A - 10 to 15 m Schreyeralmkalk : thick banked, red micritic, mostly strongly condensed limestone.
- B - 20 to 50 m gray-violet (gray-yellow) Hallstatt limestone, 10 to 20 cm thick, layered, somewhat pebbly, with basal chert .
- C - 5 to 15 m Draxlehner Kalk : Red Hallstatt lumbar lime with a 10 to 30 cm thick layer.
- D - up to 50 m Hallstatt bench lime lime often with manganese - iron oxide crusts.
- E - 30 to 50 m of massive fossil-poor micritic white, yellowish to pink colored fossil-poor lime.
- F - Hallstatt red limestone: flat to wavy micrite. The generally red limestone becomes light gray to whitish gray towards the top.
See also
literature
- Alexander Tollmann: Analysis of the classical North Alpine Mesozoic. Stratigraphy, fauna and facies of the Northern Limestone Alps . Part II of the monograph of the Northern Limestone Alps, Verlag Deuticke, Vienna 1976, ISBN 3-7005-4412-X .
Individual evidence
- ↑ Ulrike Pistotni: Facies and tectonics of the Hallstatt Zone from Bad Ischl - Bad Aussee (Salzkammergut, Austria) . In: Communications from the Geological Society. Vienna, 66. – 67. Volume, 1973/74, page 147. PDF file
- ↑ Stratigraphic table of Austria 2004 (PDF file; 381 kB) ( Memento of the original from April 24, 2018 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
