Mineral found in granite radiometric dating

Posted by / 15-Jul-2020 14:57

Whereas, the collision of the Armorican micro-continent, with both the East European Craton and Avalonia, followed the later closure of the Rheic and Theic Oceans (Galiza-Central Massif Ocean, e.g., Matte 1991, Rey et al. The southerly European Alpine orogenic belt is mostly of Caenozoic age.In Europe, the precise locations of separate terranes, fault-bounded blocks of continental crust, usually smaller than microcontinents, related to Avalonia or Armorica are poorly exposed and concealed beneath younger rocks.At present, Europe forms the western part of the Eurasian Plate.In the Mediterranean region it abuts against the African Plate to the south which, combined with the broadly SE-directed ridge-push forces of the mid-Atlantic Ridge, and the beginning of an eastward Atlantic plate compression along Iberia, give a broadly NW-SE maximum horizontal crustal compressive stress throughout much of western and central Europe.The East European Craton (EEC) comprises Precambrian rocks of the Baltic, Ukraine and Voronezh shields, together with the Russian or East European Platform, where the EEC is covered by relatively thin, undisturbed, Phanerozoic rock sequences.In contrast, the mobile belts to the south and west comprise Proterozoic-Palaeozoic crustal blocks (or 'microcontinents'), which originated as part of the southern Gondwana continent, tectonised by end-Precambrian Cadomian orogenesis that became attached to the south west margin of the EEC in Palaeozoic times.The boundary between these two regions is marked by the NW-SE-trending Trans-European Suture Zone (TESZ) (previously known as the Trans-European Fault, the Tornquist Line or the Tornquist-Teisseyre Line), which extends for approximately 2000 km from the North Sea to the Dobrogea region of the Black Sea.The TESZ is everywhere obscured and concealed beneath Mesozoic and Caenozoic sediments, but it has been reasonably well-defined as a broad zone of NW-SE-striking faults by subsurface geology, drilling results and geophysical methods, including deep seismic reflection data.

Fig 1 The small outcrop of Laurentian, the Lewisian Gneiss Complex of NW Scotland, has remained tectonically stable since Proterozoic times.

Other eminent pioneering figures are Leonardo da Vinci (1452-1519 AD), Abb Anton Lazzaro Moro (1687-1740 AD) and Antonio Vallisnieri (1661-1730 AD) in Italy, Conrad Gesner (1516-1565 AD) in Switzerland, Nicolaus Steno (1638-1686 AD) in Denmark, Abraham Gottlob Werner (1750-1817 AD) in Germany, Jns Jacob Berzelius (1779-1848 AD) in Sweden, William Smith (1769-1839 AD), the father of English Geology, Charles Lyell (1797-1875 AD) and James Hutton (1726-1797 AD) in the United Kingdom, Georges Cuvier (1769-1832 AD) and Alexandre Brongniart (1770-1847 AD) in France, and Andreas Kordellas (1836-1909 AD) in Greece, working from the 15th to the late 19th centuries, to provide information on mineralogy, crystallography, palaeontology, stratigraphy and mineral resources.

Hence, the continent's stratigraphy and structure has been studied for almost 500 years.

These crustal blocks, belonging to Eastern Avalonia, now form part of the basement of the English Midlands, the southern North Sea, and Armorica extending from western Iberia and Brittany eastwards through central Europe to the Bohemian Massif.

The plate tectonic collision of Eastern Avalonia with the East European Craton followed closure of the Lower Palaeozoic Tornquist Sea in late Ordovician to Silurian times.

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The oldest Precambrian basement provinces of western and central Europe, therefore, comprise the East European and Hebridean cratons, the stable Cadomian blocks of the London Platform and the East Silesian Massif, and the Caledonian, Variscan and Alpine fold belts.

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