GeoResources - Triassic Geodynamic Evolution, Tethyan, Central European and Atlantic Domains


	Triassic Geodynamic Development of the Tethyan, Central European and Atlantic Domains Introduction and Detailed Description





	Introduction In the European realm (northern Peri-Tethys) the Triassic was a time of plate re-organization between the Hercynian suturing of the Pangea Supercontinent in the Early Carboniferous to Early Permian and its main breakup since the Early to Middle Jurassic. Large-scale plate-tectonic developments which influenced Central Europe by far-field plate stresses include (Ziegler et al. 1988; Dercourt et al. 2000; Gaetani 2000a, 2000b, 2000c; Stampfli et al. 2001a, 2001b; Stampfli & Borel 2004; Ziegler et al. 2001): 1) rapid westward propagation of rifting and sea-floor spreading in the early Neotethys linking up to the Central Atlantic rift system in Rhaetian to Sinemurian. The present post-Alpine suture line runs between Arabia and Iran. 2) northward propagation of rifting in the future Central Atlantic domain. Sea-floor spreading did not develop before the late Pliensbachian (Steiner et al. 1998, Zühlke et al. 2004). 3) southward propagation of rifting in the future North Atlantic domain (a.o. Norwegian-Greenland Sea Rift, Rockall-Faroer Rift). Sea-floor spreading did not develop before the early Barremian (Boillot et al. 1987). 4) progressive subduction of the Paleotethys at the southern margin of the Eurasian platform, and finally accretion of Cimmerian terranes. The present post-Alpine suture line runs north of Iran, between the Cimmerian Terranes and Europe. 5) back-arc extension and sea-floor spreading behind the Paleotethys subduction zone resulting in a series of small oceanic basins (Meliata-Halstatt, Küre and Maliac in the Triassic, Pindos and Vardar in the Jurassic). Central and Western Europe were bounded by the Tornquist-Tesseiyre line in the northeast against the Baltic Shield and East European Platform (Dercourt et al. 2000). The Tornquist-Teisseyre line represents a (sub-)vertical fault system, which crosses the North Sea, the Polish Trough, the Carpathian flysch basin and Dobrogea. It separates the stable eastern European platform with high lithospheric thickness as far as the Uralian chain from Central and Western Europe with lower lithospheric thicknesses. In the south to southwest the North African line separated former Laurussia from Gondwana. The Iberian microplate acted as a separate block, being separated from Africa and Western-Central Europe by transcurrent fault systems (Olivet 1996). In the northwest, the initial North Atlantic rift system (Rockall-Faroe Trough, East Greenland Rift) bounded Western-Central Europe against Greenland. During the Triassic, epicontinental Central Europe experienced thermal/gravity relaxation and extension at the plate-scale as well as multi-directional rifting and transtension/-pression at regional scale. Hercynian domains were progressively transected. Major grabens include the Viking-Central Graben and Horn Graben of the North Sea, the Glückstadt Trough of northern Germany, the North Danish-Polish-Dobrogea Trough, the graben system on the western shelf of the British Islands (Western Approaches, Celtic Sea-Bristol Channel, Porcupine Troughs; Manx-Furness, Minches Basins), the Bay of Biscay Rift and the Atlas-South Iberia Graben System (see Ziegler 1988, Fisher & Mudge 1998). Graben development was governed by the reactivation of Permo-Carboniferous fracture systems. Thicknesses of Triassic graben fills range between 3000 and more than 4000 m (Ziegler 1988). The development of the Eastern and Southern Alpine realms, which were situated outside the epicontinental Central European basin on the northwestern shelf of the Paleotethys (PT-boundary to Anisian) and backarc basins adjacent to the Neotethys (Meliata-Hallstatt and Maliac oceans, Ladinian-Sinemurian) is different. The Southern Alps shared a transtensional and transpressional regime with strong differential subsidence/uplift (Rüffer & Zühlke 1995), however without the conspicious rifting (see project "Triassic Basin Fill and Development of the Southern Alps "), that characterizes the epicontinental Central European Basin. Thickness of the Triassic basin fill ranges between 1800 m and 5000 m. The Northern Calcareous Alps experienced a more persistent development with gradual subsidence changes in time and space (Rüffer & Bechstädt 1998; Rüffer in Feist-Burckardt et al. 2008). The detailed description includes external links to the "Tethyan Plate Tectonics Homepage" at the University of Lausanne for plate-tectonic reconstructions (images, modified from Stampfli and Borel, 2004).

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GeoResources - Triassic Geodynamic Evolution, Tethyan, Central European and Atlantic Domains

Triassic Geodynamic Development of the Tethyan, Central European and Atlantic Domains