Journal of Alpine Geology, 54: 323-377, Wien 2012 End-Triassic crisis events recorded in platform and basin of the Austrian Alps. The Triassic/Jurassic and Norian/Rhaetian GSSPs BY SYLVAIN RICHOZ, LEOPOLD KRYSTYN, AXEL VON HILLEBRANDT & ROWAN MARTINDALE With 54 figures Field Trip Guide 29th IAS Meeting of Sedimentology Schladming/Austria Adresses of the authors: SYLVAIN RICHOZ Austrian Academy of Sciences Commission for the Palaeontological and Stratigraphical Research of Austria c/o Institut of Earth Sciences, Graz University Heinrichstraße 26 8010 Graz Austria Email: [email protected] LEOPOLD KRYSTYN Vienna University Department for Palaeontology Althanstrasse 9 1090 Vienna Austria Email: [email protected] Journal of Alpine Geology 54 S. 323-377 Wien 2012 323 RICHOZ et al.: End-Triassic crisis events recorded in platform and basin of the Austrian Alps ... AXEL VON HILLEBRANDT Technische Universität Berlin Institut für Angewandte Geowissenschaften Ernst-Reuter-Platz 1 10587 Berlin Germany Email: [email protected] ROWAN MARTINDALE University of Southern California Department of Earth Sciences 3651 Trousdale Parkway Los Angeles, California 90089-0740 United States Email: [email protected] Content Abstract........................................................................................................................................................................324 1. Topics and area of the field trip...................................................................................................................................325 2. Introduction...............................................................................................................................................................325 2.1. The Northern Calcareous Alps............................................................................................................................325 2.2. Principles of the structural evolution...................................................................................................................326 2.3. Triassic depositional realms................................................................................................................................327 2.3.1. General features.......................................................................................................................................327 2.3.2. The Dachstein facies................................................................................................................................330 2.3.3. The Zlambach facies................................................................................................................................332 2.3.4. The Hallstatt facies - the deep shelf environment......................................................................................332 2.3.5. The Eiberg Basin.....................................................................................................................................333 3. The Field Trip............................................................................................................................................................333 3.1. The Hallstatt and Zlambach facies......................................................................................................................333 3.1.1. Route.......................................................................................................................................................333 2.1.2. Locality 1: Leislingkogel..........................................................................................................................334 3.1.3. Locality 2: Grosser Zlambach...................................................................................................................336 3.1.4. Locality 3: Steinbergkogel: the Norian-Rhaetian GSSP proposed section..................................................336 3.2. The Dachstein Reef, its lagoon and its margin.....................................................................................................342 3.2.1. Route.......................................................................................................................................................345 3.2.2. Locality 4: Gosausee: The Dachstein margin at Gosaukamm....................................................................346 3.2.3. Locality 5: Tennengebirge - Eisenriesenwelt, Initial start of the reef..........................................................347 3.2.4. Locality 6: Pass Lueg: the classical Lofer cycle.........................................................................................350 3.3. The fringing reefs...............................................................................................................................................352 3.3.1. Route.......................................................................................................................................................353 3.3.2. Locality 7: Adnet......................................................................................................................................354 3.3.3. Locality 8: Steinplatte..............................................................................................................................356 3.4. The Eiberg Basin....................................................................................................................................................361 3.4.1. Route.......................................................................................................................................................361 3.4.2. Locality 9: Eiberg.....................................................................................................................................362 3.4.2.1. The Hochalm Member.................................................................................................................364 3.4.2.2. The Eiberg Member....................................................................................................................365 3.4.3. Locality 10: Kuhjoch: The Triassic-Jurassic GSSP....................................................................................365 4. Concluding remarks..................................................................................................................................................373 References.......................................................................................................................................................................373 Abstract Calcareous Alps built a region of huge carbonate platforms with large lagoons and intra-platform basins in the north During the latest Triassic, the Austrian Northern and prominent fringing reefs in the south facing a 324 Journal of Alpine Geology, 54: 323-377, Wien 2012 southward transition to the open-ocean where pelagic off- the basin during the end-Triassic crisis. shore facies developed. Within the Norian inshore platform sediments, one can find the type sections of the lagoonal This field trip will allow Dachstein facies with classic peritidal Lofer cycles, and i) to see both the Norian/Rhaetian and Triassic-Jurassic towards off-shore those of the Dachstein reef and the Hall- GSSPs (Global Stratotype Section and Point), statt facies (condensed pelagic limestone). In the early ii) to see how Upper Triassic biotic crisis events are Rhaetian, the diversity of the pelagic fauna began to decline recorded in basinal and platform settings of this whereas the reefs reached their climax. The Northern classical carbonate sedimentology study area and Calcareous Alps record this final bloom, the following iii) to understand the sedimentary interactions between stepwise decline and drowning/extinction history with, platform and basin during this time of multiple crisis. finally, the ultimate breakdown of the carbonate factory This whole Late Triassic story is present in the Northern on the platform during the end-Triassic crisis, and the Calcareous Alps (Salzkammergut region, Salzburg, and expression of this breakdown in the basin. Two GSSPs Tirol), a scenic, mountains and lakes region with (Global Stratigraphic Section and Point), for the Rhaetian breathtaking landscapes (Fig. 1). and the Hettangian stages - the later defining the boundary between the Triassic and Jurassic system - corroborate the global geological importance of the area during that interval of time. 2. Introduction This general introduction is mainly taken from MANDL (2000). 1. Topics and area of the field trip The Austrian Northern Calcareous Alps give the 2.1. The Northern Calcareous Alps opportunity to observe the influence of the Late Triassic crisis intervals on the sedimentary record of various settings One of the most prominent units of the Eastern Alps is the (lagoon, reefs, intra-platform basin, slope, pelagic plateau). nappe complex of the Northern Calcareous Alps, which The Norian inshore platform sedimentation with typical forms a 500 kilometres long and 20 to 50 kilometre wide peritidal Lofer cycles, the barrier reef facies and the off- thrust belt of sedimentary rocks (Fig. 2). The sedimentary shore Hallstatt type facies (red condensed pelagic features in the Northern Calcareous Alps are mostly well limestone) will all be visited in their type areas. The reefs preserved, due to only local metamorphic overprint, which are still flourishing during the Lower Rhaetian despite the offers