Explanatory notes to the digital geological map of the Rax ... - KATER

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KATER II Geology of the Rax-Schneeberg-region __________________________________________________________________________________________ UPPER CARNIAN TO RHAETIAN (60) - (52) As sealevel started rising up again in the Upper Carnian, rather slowly in the beginning, carbonate production increased, locally filling a relief in the drowning platforms with the dasycladacean bearing lagoonal Waxeneck Limestone (60). The relief (several 10th up to about 100 meters) may have been caused by erosion during the lowstand time and /or by tectonic movements. A transgressive pulse just below the Carnian/Norian boundary caused an onlap of pelagic limestones over the shallow water carbonates and initiated the rapid growth of the Norian carbonate platform. Due to local differences in platform growth conditions we can distinguish two different developments: In the central part of the NCA (Hochkönig, Tennengebirge, Dachstein area etc.) the pelagic onlap represents only a short time interval and became covered by the prograding Dachstein carbonate platform – in these areas the Upper Triassic reefs approximately are situated above the Middle Triassic ones. Another situation characterizes the eastern sector of the NCA. There the Uppermost Carnian pelagic transgression continues until the Upper Norian and has been termed Mürztal Type of Hallstatt facies. Dachstein reefs are only known from the Upper Norian and these ones are situated above the former platform interior, several kilometers behind the former Wetterstein reef front. This "backstepped" reefs show transitions into the partly restricted basinal facies of the Aflenz Limestone (59), a bedded black limestone with chert layers or nodules. In contrary the "Southern Marginal Reefs" of central NCA are connected by the allodapic Gosausee Limestone to the Pötschen Limestone (58), a bedded grey limestone with chert, representing the basinal realm of Hallstatt deep shelf. The Hallstatt-Group (57) - (54) shows a great variability of multicolored limestones often with rapidly changing sedimentary features due to the mobile basement: The Hallstatt Limestone at Nasswald (57) consists of massive to bedded grey pelagic limestones with a Norian fauna. Hallstatt Limestone of Mürztal facies (55) The grey, pink and reddish, more or less massive limestones represent sediments on a „pelagic plateau“ above the drowned Waxeneck limestone and Wetterstein platform. The uppermost part, consisting of well bedded dark limestone (56), is shown separately on the map. Hallstatt Limestone of Salzberg facies (54) At Losenheim there occurs massive white limestone (“Massiger Hellkalk”) und well bedded red limestone (“Hangend Rotkalk”). It is comparable to the Salzberg facies of the classical Hallstatt area in the Salzkammergut, representing the reduced sedimentation above local uplifts due to diapirism of Permian evaporites. Zlambach Formation (53, 52) In the Triassic basinal realms Zlambach marls (53) and bedded black limestones (53) have been deposited. Along the basin margins they onlap and interfinger with the the Dachstein platform slope sediments. 11
KATER II Geology of the Rax-Schneeberg-region __________________________________________________________________________________________ 12 Fig. 2:
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Explanatory notes to the digital geological map of the Rax ... - KATER

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