Characteristics of the Lofer cyclicity in the type locality of the Dachstein Limestone (Dachstein Plateau,Austria) |
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Authors: | János Haas Harald Lobitzer Miklós Monostori |
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Institution: | 1.Geological Research Group of the Hungarian Academy of Sciences,E?tv?s Loránd University,Budapest,Hungary;2.Lindaustrasse 3,Bad Ischl,Austria;3.Paleontological Depatment,E?tv?s Loránd University,Budapest,Hungary |
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Abstract: | In the present paper, the results of our studies in the type locality of the Dachstein Limestone are summarised in order to
contribute to the correct interpretation of the Lofer cycles. In the sections studied on the Dachstein Plateau, the boundaries
of the Lofer cycles are usually erosional disconformities showing karstification features. Penetration by karstic solution
was not more than a few decimetres, since during the recurrent sea-level drops the platform only slightly emerged above sea
level. The reddish or greenish argillaceous carbonate interlayers (facies A) cannot be interpreted as in situ palaeosol horizons.
They are tidal flat deposits consisting predominantly of subtidal carbonate mud redeposited by storms that was mixed with
reworked airborne fine carbonate particles and argillite and/or reworked lateritic soil, which were accumulated on the subaerially
exposed platform. Rip-ups from consolidated sediment, blackened intraclasts and skeletons of tidal flat biota may have also
contributed to the sediment of facies A. Erosional boundaries of most of the investigated cycles, and definite features of
karstic solution beneath the disconformities, suggest periodical drops of sea level followed by a renewed transgression. This
appears to confirm the allocyclic model for the explanation of the origin of the Lofer cycles. |
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Keywords: | Upper Triassic Northern Calcareous Alps Carbonate platform Sedimentary cycles Peritidal facies Palaeokarst |
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