Astronomical control on the origin and preservation of Lofer cyclicity in the Late Triassic Dachstein platform

The Upper Triassic Dachstein Limestone is an archetypal example of platform carbonate formation that consists of peritidal-subtidal Lofer cycles. However, despite a long history of study, their allocyclic vs autocyclic origin remains controversial. Using modern cyclostratigraphic methodology, here we revisit archive data of the Dachstein Limestone in Core Po-89 from the Transdanubian Range, Hungary. Analysis of high-resolution stratigraphic series of the Lofer facies types, colour, and greyscale reveals spectral peaks that can be identified as Milankovitch cycles. The Lofer cycles correspond to a robust peak with a wavelength of 3.6 m that is the expression of one of the precession frequencies. The sedimentation rate is 15–17 cm/kyr, thus the studied core section represents 2.4–2.7 Myr. Our model of cyclic carbonate deposition suggests that aquifer- and limno-eustasy were the most likely drivers of cyclic sea level changes. Differences in the depositional processes and preservation of the Lofer cycles led to variations in their completeness that seems to be also astronomically controlled. Our results are consistent with other studies of Upper Triassic Lofer cyclic successions. The similarities in the thickness of individual Lofer cycles, and the periods of all identified cycles suggest common allocyclic processes. Our findings provide evidence for the astronomical forcing of carbonate sedimentation in the Late Triassic Dachstein platform system. • High-resolution cyclostratigraphy of Dachstein Limestone core logs. • Lofer cycles are astronomically controlled and represent precession cycles. • Completeness of preserved Lofer cycles also responds to astronomical forcing. • Lofer cyclicity may reflect sea level changes driven by aquifer- and limno-eustasy. • Similar cyclic deposition was widespread on Late Triassic carbonate platforms.