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The Earth: Surface, Structure and Age
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
The term plate tectonics came to be used to denote the processes involved in the movements and interactions of the plates (‘tectonic’ is derived from Greek tekton, a builder). Where two continental plates have converged, with the formation of a belt of intercontinental fold-mountains such as the Alpine-Himalayan orogenic belt (p. 17), the term collision zone can be used.
Has the tectonic regime of the Baltic Shield always remained the same?
Published in GFF, 2022
The Mylonite Zone (Figs. 6 and 7) separates the Klarälven and Ätran terranes from the younger western terranes. In the north-west, the Zone is hidden below the Caledonides and cut by the formation of the Iapetus Ocean. It runs as a steeply dipping zone in a south-eastern direction turning towards the south (Lindh 1974); it may be interpreted as a large sinistral shear zone (Fig. 6). A number of small younger faults offsets the major faults (Lindh et al. 1998). To the south of Lake Vänern, it gradually becomes less steep (e.g., Samuelsson 1978) and turns sharply westwards shortly north of the eclogite-bearing area (Figs. 6 and 7). The east-west striking part of the mylonite zone slopes gently northwards (Möller 1998), suggesting a change in mutual relations between the Idefjorden and Ätran terranes, from a strike-slip to a thrust movement. The younger age and the totally different lithologies of the Idefjorden block compared to neighbouring areas in the east hint to a plate movement along a transform fault replaced by a collision zone including subduction in the south. This replacement involves an almost 90° turn of the zone. Its western continuation is hidden below the Skagerrak and the Danish platform sediments. Movements along the much younger Tornquist-Teisseyre zone (Fig. 6) further complicates the pattern.
Lithospheric evolution, thermo-tectonic history and source-rock maturation in the Gippsland Basin, Victoria, southeastern Australia
Published in Australian Journal of Earth Sciences, 2022
J. Röth, A. Parent, C. Warren, L. S. Hall, D. Palmowski, N. Koronful, S. S. Husein, V. Sachse, R. Littke
The crustal layer model suggests that during the Late Jurassic, the lithosphere below the eastern margin of Gondwana was ∼70 km thick (at least behind the collision zone). The crustal thickness varied between ∼50 km below southeast Australia and ∼35 km below Tasmania, while it measured probably only ∼25 km below the SAFZ—the area where the Gippsland Basin subsequently formed (see Figure 8). However, these values do not include possible paleo-elevation (as discussed above), which should be added to the crustal thickness and would affect the isostatic and geometric evolution of the lithosphere.
Inversion tectonics in the Sorgenfrei–Tornquist Zone: insight from new marine seismic data at the Bornholm Gat, SW Baltic Sea
Published in GFF, 2022
Yaocen Pan, Elisabeth Seidel, Christopher Juhlin, Christian Hübscher, Daniel Sopher
The Alpine-Tethys plate boundary processes controlled the intraplate compressional deformation in north-central Europe during the Late Cretaceous-Paleocene inversion (Stephenson et al. 2020). The large-scale intraplate compression, between Africa, the Iberian Microplate and southern Europe, occurred primarily during the Sub-Hercynian phase of Santonian-Maastrichtian times, driven by the high strength of the lithosphere at the convergent plate boundary between Iberia and Europe (Kley & Voigt, 2008; Dielforder et al., 2019). Subsequently, progressive formation of plate boundary faults, as Iberia underthrusts Europe, led to the destruction of the mechanical coupling (Dielforder et al., 2019), and convergence was largely accommodated locally instead of being transmitted further northeastward. Concurrently with the period of quiescence during the Paleocene at the Pyrenees (Rosenbaum et al., 2002), the drift of the Adria microplate towards Europe accelerated (Handy et al., 2010), resulting in the subduction and closure of the external oceanic zones (Alpine-Tethys realm) with intervening continental ribbons (Plašienka, 2018). The shortening and subduction events at the Carpathian collision zone, e.g., the Inner Carpathians, were thought to have facilitated transmission and build-up of compressional stresses in the foreland area of the eastern SPB, with their timing conforming well with inversion movements in the Carpathian foreland of the Polish Basin (Krzywiec, 2002). The compressional regime may have been maintained during the latest Cretaceous through early Paleogene, which led to uplift and erosion in the Western Carpathian orogenic wedge area, and widespread basin inversion in the external Western Carpathians (Flysch Belt), with the climax believed to have been in the Maastrichtian-Paleocene (Oszczypko, 2006; Plašienka & Soták, 2015).