Title: The tectonic evolution of the Welsh Caledonides
Abstract: Summary The succession, metamorphism, geochronology and major structure of the Mona Complex, Arvonian and Lower Palaeozoic rocks of N Wales are outlined. This results in a model which relates early (pre-Ordovician) NW-verging structures to the closing of an early Caledonian ocean and obduction of deep water sediments, slide breccia and basic volcanic rocks on to the sediments previously metamorphosed, locally at high temperatures, and intruded by granites in central and N Anglesey. The pattern of folds, cleavages, thrusts and finite strain states in N Wales are described. A maximum of 43 km shortening between the Menai Straits and the Welsh Borderlands is estimated across the more highly deformed part of central Snowdonia, during end-Silurian deformation. The amount of shortening decreases to the northeast (Denbighshire Basin) and south (Harlech Dome) ends of the arc. This is attributed to compression of Snowdonia against a rigid block situated in the Berwyn Hills. The SE-verging structures are thought to pass downwards, with listric geometry, into a decollement zone at some unknown depth in the basement, which accommodated Caledonian crustal shortening across Wales, and must itself either descend into the mantle or root in any Caledonian suture beneath the Irish Sea.
Publication Year: 1979
Publication Date: 1979-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 55
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