Guidelines for stratigraphic nomenclature: Swiss Committee of Stratigraphy

No Abstrac

The evolution of the northern margin of the Tethys in eastern Switzerland

The former northern margin of Tethis is being studied in the Alpine chain by IGCP Project 198("Evolution of the Northern Margin of the Tethys"). This paper summarizes the present state of the knowlege from the opening phase of this Mesozoic to early Paleogene seaway in Eastern Switzerland. Basement rocks and sediments of the previous margin are now exposed here in the stack of the Alps and their European foreland

Mesozoïc subsidence history of the European marginal shelves of the alpine Tethys (Helvetic realm, Swiss Plateau and Jura)

Based on a palinspastic restoration of the Helvetic realm, the Swiss Plateau and the Jura, the Mesozoic subsidence history of this area is reconstructed using about 50 stratigraphic sections and by taking into account the following parameters: age of the sediments, compaction corrected thickness, depositional depth estimations and eustatic sealevel corrections for each lithological unit. The following major subsidence phases may be deduced from the geohistory diagrams: - Triassic (mainly in the Jura), - Early Jurassic (in the southernmost and western Helvetic realm), - Early Cretaceous (in the southernmost and western part of the Helvetic and Subalpine realms). In the Jura, the Triassic and Middle Jurassic phases are probably due to intracontinental rifting following Late Variscan structures. The Early Jurassic phase due to extensional tectonics is locally well established in the Helvetic realm. For the Late Jurassic and Early Cretaceous phases, the subsidence is mainly due extensional tectonics on the northern margin of the Tethys

Richtlinien für den Gebrauch der stratigraphischen Nomenklatur: Lithostratigraphie und Chronostratigraphie

ISSN:0012-9402ISSN:1420-912

Cretaceous

The Cretaceous evolution of sedimentary basins in Central Europe was influenced by the interplay of two main processes: plate tectonics and eustatic sea-level change. Global plate-tectonic reconfiguration resulted in the widening of the Central Atlantic, the opening of the Bay of Biscay, and the opening of the South Atlantic Ocean causing a counter-clockwise rotation of Africa coeval with the closure of the Tethys Ocean. Convergence between the European and African plates led to the formation of the Alps and the Western Carpathians as a classic thrust orogen. Several orogenic phases can be distinguished. The Jurassic - Cretaceous, Eo-Alpine orogeny was followed by Meso- and Neo-Alpine deformational events (e.g. Faupl & Wagreich 2000; see also Froitzheim et al. 2008; Reicherter et al. 2008). During the Early Cretaceous, ongoing rifting of the North Sea Graben system and the resulting stress pattern produced a variety of smaller, partly isolated basins in Central Europe. The late Palaeozoic - early Mesozoic rifting in the North Sea ceased in late Early Cretaceous times and thermal subsidence prevailed in western and central Europe from the Albian to the Turonian. Elevated spreading rates along mid-ocean ridges and increased rates of intra-oceanic plateau volcanism resulted in the highest global sea level during Phanerozoic times (Haq et al. 1988; Hardenbol et al. 1998). The former margins of Early Cretaceous basins were flooded worldwide, and several new seaways connected the cold Boreal areas of the Arctic and western Siberia with the warm subtropical Tethys Ocean. Central Europe evolved into an extended epicontinental shelf sea with a variety of intrashelf basins. The palaeogeography of southern Central Europe is determined by the convergence of Europe and Africa and can be divided into: (1) a southern European passive margin, which comprising the Helvetic, the Outer Carpathians and other comparable European shelf units on continental crust (including Subpenninic units sensu Schmid et al. 2004); (2) the units of the Liguria-Piemont-Penninic ocean system; and (3) the northern margin of the Adriatic plate comprising the Austro-Alpine, the Inner Western Carpathians (Fatric, Tatric), and the Southern Alpine units