International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Siliciclastics in the Upper Triassic dolomite formations of the Krizna Unit (Mala Fatra Mountains, Western Carpathians): constraints for the Carnian Pluvial Event in the Fatric Basin

Published: Apr 2011

Pages: 121 - 138



Abstract: The Upper Triassic carbonates of the Krizna Unit in the eastern part of the Krivanska Mala Fatra Mts contain the unique siliciclastic interbeds. They are developed between the Ramsau Dolomite Formation and the Hauptdolomite Formation, and comprise alternating dark grey shales and pale grey dolomites. Such a shaly-dolomite formation is unknown from the Upper Triassic formations of the Krizna Unit, which makes it possible to define a new lithostratigraphic unit (Trzinovo Formation). The Ramsau Dolomites beneath the Trzinovo Formation contain microfauna of Carnian foraminifers. Therefore, the Carnian age has also been constrained for the Trzinovo Formation, which by the reduced carbonate productivity and enhanced terrigenous influx could be related to the Reingraben Event. This event related to the “Carnian Pluvial Episode” is also inferred in the Trzinovo Formation by the presence of lingulide brachiopods (Lingularia) and spinicaudatan crustaceans (Euestheria). This fauna provides evidence of not fully marine conditions of the Trzinovo Formation, influenced by continental freshwater influx and humid climate.

Keywords: Carnian event, Upper Triassic dolomites, Western Carpathians, Krizna Unit, shaly interbeds, lingulids, conchostracans

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