Late Triassic to Early Jurassic palaeogeography and eustatic history in the NW Tethyan realm: New insights from sedimentary and organic facies of the Csovar Basin (Hungary)

Abstract

Sedimentary and organic facies of a continuous Late Triassic–Early Jurassic toe-of-slope to basin succession of the NE Transdanubian Range (N Hungary) was studied in order to reconstruct the palaeogeographical and eustatic evolution of the Csovár Basin, an intraplatform basin of the NW Neotethys margin. Characteristic facies successions point to sea-level changes of different hierarchies. Cyclic patterns, inferred to result from orbital eccentricity forcing, are also reflected in the stratigraphical distribution of sedimentary organic matter. Furthermore, both palaeontological and isotope data document drastic climatic changes around the Triassic–Jurassic boundary. Detecting sea-level changes leads to a more accurate interpretation of the Late Triassic palaeogeographic setting and evolution of the Transdanubian Range's carbonate platform. Our integrated sedimentological and palynological data suggest a complex topography and dynamic sea-level history, which contradicts a previous model of broad, uniform platform setting and lack of any major drowning and emersion events during the Late Triassic.