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

Correlation of Tethyan and Peri-Tethyan long-term and high-frequency eustatic signals (Anisian, Middle Triassic)

Published: Aug 2008

Pages: 307 - 317


Abstract: During Anisian times, broad ramp systems developed on the northwestern Tethys shelf and in the adjacent Peri-Tethyan realm. In both paleogeographical settings carbonate series display characteristic cyclic patterns, reflecting long-term and high-frequency eustatic sea-level changes. Facies successions recognized within the small-scale sedimentary cycles document a rapid transgressive phase followed by a prolonged highstand phase. The erosional base of these deposits is interpreted as a sequence boundary. Transgressive deposits are characterized by bioclastic limestones with reworked lithoclasts. Bioturbated mudstones represent the highstand deposits. Sedimentation of laminated mudstones is documented during the late highstand phase. Maximum flooding is recognized by thin condensed marly layers at the top of bioclastic beds. Such meter-scale sedimentary cycles are the basic stratigraphic building blocks of the Anisian series of Hungary and Germany, representing ramp deposits of the proximal Tethys shelf and the northern Peri-Tethys Basin, respectively. Comparison of both depositional environments leads to a better understanding of cyclic sedimentation of shallow-water carbonates and controlling factors. Eustatic signals of different scales are analysed and used for correlation of sedimentary series between different paleogeographical settings.

Keywords: Anisian, Germany, Hungary, Peri-Tethys Basin, NW Tethys shelf, sedimentary cycles, carbonate ramps

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