Late Cretaceous to Early Tertiary palaeogeography of the Western Carpathians (Slovakia) and the Eastern Alps (Austria): implications from heavy mineral data

The Late Cretaceous Brezová and Myjava Groups of the Western Carpathians in Slovakia and formations of the Gosau Group of the Northern Calcareous Alps in Lower Austria comprise similar successions of alluvial/shallow marine deposits overlain by deep water hemipelagic sediments and turbidites. In both areas the heavy mineral spectra of Late Cretaceous sediments contain significant amounts of detrital chrome spinel. In the Early Tertiary the amount of garnet increases. Cluster analysis and correspondence analysis of Coniacian/Santonian and Campanian/Early Maastrichtian heavy mineral data indicate strong similarities between the Gosau deposits of the Lunz Nappe of the north-eastern part of the Northern Calcareous Alps and the Brezova Group of the Western Carpathians. Similar source areas and a similar palaeogeographical position at the northern active margin of the Adriatic/Austroalpine plate are therefore suggested for the two tectonic units.Basin subsidence mechanisms within the Late Cretaceous of the Northern Calcareous Alps are correlated with the Western Carpathians. Subsidence during the Campanian-Maastrichtian is interpreted as a consequence of subduction tectonic erosion along the active northern margin of the Adriatic/Austroalpine plate. Analogous facies and heavy mineral associations from deep water sandstones of the Manin Unit and the Klape Unit indicate accretion of parts of the Pieniny Klippen Belt during the Late Cretaceous along the Adriatic/Austroalpine margin.     

Die muttekopfgosau (Lechtaler Alpen,Tirol/Österreich): Sedimentologie und Beckenentwicklung

In the Eastern Alps compression during orogeny in the Upper Cretaceous caused crustal thickening, isostatic uplift and gravitational adjustment of the unstable orogenic wedge. This process triggered extensional basin formation on the back of the orogen (Gosau Basins). The basin fill of the Muttekopf Gosau Basin is arranged in megacycles, the first one comprising alluvial fan sediments and “Inoceramus marls” of the Lower Gosau Complex (Faupl et al. 1987) of Santonian age. Three other cycles follow (Upper Gosau Complex, Campanian to Maastrichtian), consisting of turbiditic fining upward sequences, that are indicative for extensional tectonics during basin formation, as subsidence events prevent formation of autocyclic coarsening upward sequences and therefore prograding of the turbidite system. Deposition of the 1st and 2nd Megacycle occured below the CCD (Carbonate Compensation Depth). The carbonate rich 3rd Megacycle was deposited probably below the CCD after a period of palaeogeographic reorganisation (uplift?) in the source area.     

Geochemistry of fine-grained sediments of the upper Cretaceous to Paleogene Gosau Group （Austria, Slovakia） Implications for paleoenvironmental and provenance studies

Bulk rock geochemistry of 169 fine-grained sediment samples of the upper Cretaceous to Paleogene Gosau Group（Northern Calcareous Alps,Austria and Slovakia） from borehole and outcrop localities was performed to separate non-marine and marine deposits.Geochemical characteristics of different Gosau depositional systems,basins and sediment provenance using major-,trace-,and rare earth elements were also investigated.Geochemical proxies such as boron concentrations were tested for seeking the possibilities of paleosalinity indicators.Due to the fact that several pelagic sections are represented by extremely low boron contents.B/Al^* ratios are recognized as more robust and differentiate reliably between marine（mean:160±34） and non-marine（mean:133±33） samples.Using statistical factor analysis,hemipelagic to pelagic samples from the Gieβhbl Syncline and Slovakian equivalents can be differentiated from marginal-marine to non-marine samples from the Grnbach and Glinzendorf Syncline related to terrigenous（SiCh.Al₂O₃,K₂O,Th,Rb,Zr and others） and pelagic indicative elements （CaO,Sr,TOT/C and B/Al^*）.A clear indication for ophiolitic provenance is traced by high amounts of chromium and nickel.Only non-marine successions of the Glinzendorf Syncline show higher Cr and Ni concentrations（up to 250 and 400 ppm,respectively） and enriched Cr/V and Y/Ni ratios trending to an ultramafic source.     

Correlation of late Cretaceous calcareous nannofossil zones with ammonite zones and planktonic Foraminifera: the Austrian Gosau sections

The late Turonian to early Campanian calcareous nannofossil biostratigraphy of the Austrian Gosau Group is correlated with ammonite and planktonic foraminiferal zones. The standard Tethyan zonations for nannofossils and planktonic foraminifers are applied with only minor modifications. The basal marine sediments of the Gosau Group, bearing late Turonian-early Coniacian macrofossils, belong to the Marthasterites furcatus nannofossil Zone (CC13). The Micula decussata Zone (middle Coniacian to early Santonian) is combined with the Reinhardtites anthophorus Zone because of the rare occurrence of Renhardtites cf. R. anthophorus already in the Coniacian and taxonomic problems concerning the correct identification of this species. The Santonian-Campanian boundary lies within the Calculites obscures Zone (CCl7).