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摘要
New investigations on Lower Cretaceous sedimentary rocks southeast of Bad Ischl (Upper Austria) focused especially on outcrops of the Ischl Breccia. The local term "Ischler Brekzie" describes mass flows of the Rossfeld Formation of Late Valanginian depositional age at Salzberg and Kolowratshhe and of Late Hauterivian to Early Barremian depositional age in the Perneck valley. The polymictic component spectrum contains ophiolitic and siliciclastic material, derived from an ophiolitic nappe stack (Neotethyan Belt). Mixed siliciclastic-calcareous rock fragments and biogenic components originated from the Early Cretaceous shelf area. In addition, Upper Jurassic and Lower Cretaceous Oberalm and Schrambach formations occur as components. Upper Juvavic platform carbonates or Lower Juvavic hemipelagic rocks do not occur in the mass flows of the Rossfeld Formation. The evolution of the Rossfeld Formation was triggered by sea-level fluctuations and only minor tectonic activity. The alleged uniform, laterally continous Lower Cretaceous basin sequence of Bad Ischl in fact belongs to three blocks of different palaeogeographic position: The Reinfalzalm-Mitterberg Unit (distal Trattberg Rise), the Gschwandtalm-Perneck Unit (proximal Tauglboden Basin) and the Reiterndorf-Hubkogel Unit (distal Tauglboden Basin). The Alpine Haselgebirge Melange of the Bad Ischl salt deposit was resedimented within the Oberalm Formation in the Late Tithonian corresponding to the well documented Gartenau and Weitenau occurrences. Today's structural position and exposure of the Bad Ischl salt deposit was successively formed from mid-Cretaceous to Quaternary by both tectonism and erosion.
- 出版日期2015
